template

template

https://pkg.go.dev/text/template@go1.20.1

​ template 包实现了基于数据驱动的模板，用于生成文本输出。

​ 要生成 HTML 输出，请参考 html/template 包，它具有与此包相同的接口，但自动防止某些攻击来保护 HTML 输出。

Templates are executed by applying them to a data structure. Annotations in the template refer to elements of the data structure (typically a field of a struct or a key in a map) to control execution and derive values to be displayed. Execution of the template walks the structure and sets the cursor, represented by a period ‘.’ and called “dot”, to the value at the current location in the structure as execution proceeds.

​ 模板通过将其应用于数据结构来执行。模板中的注释引用数据结构的元素（通常是结构体的字段或映射中的键），用于控制执行并派生要显示的值。模板的执行会遍历数据结构并设置游标，由句点 ‘.’ 表示，称为 “dot”，在执行过程中将其设置为结构中当前位置的值。

The input text for a template is UTF-8-encoded text in any format. “Actions”–data evaluations or control structures–are delimited by “{{” and “}}”; all text outside actions is copied to the output unchanged.

​ 模板的输入文本可以是任何格式的 UTF-8 编码文本。“操作”（数据评估或控制结构）由 “{{” 和 “}}” 分隔；所有在操作外的文本都将原样复制到输出中。

Once parsed, a template may be executed safely in parallel, although if parallel executions share a Writer the output may be interleaved.

一旦解析完成，模板可以在并发环境中安全地执行，但如果并发执行共享一个 Writer，则输出可能会交错。

Here is a trivial example that prints “17 items are made of wool”.

下面是一个简单的示例，打印出 “17 件商品由羊毛制成”。

1
2
3
4
5
6
7
8
9

type Inventory struct {
	Material string
	Count    uint
}
sweaters := Inventory{"wool", 17}
tmpl, err := template.New("test").Parse("{{.Count}} items are made of {{.Material}}")
if err != nil { panic(err) }
err = tmpl.Execute(os.Stdout, sweaters)
if err != nil { panic(err) }

More intricate examples appear below.

下面是更复杂的示例。

Text and spaces 文本和空格

By default, all text between actions is copied verbatim when the template is executed. For example, the string " items are made of " in the example above appears on standard output when the program is run.

默认情况下，在操作之间的所有文本在模板执行时都会被原样复制。例如，在上面的示例中，字符串 " 件商品由 " 在程序运行时会显示在标准输出中。

However, to aid in formatting template source code, if an action’s left delimiter (by default “{{”) is followed immediately by a minus sign and white space, all trailing white space is trimmed from the immediately preceding text. Similarly, if the right delimiter ("}}") is preceded by white space and a minus sign, all leading white space is trimmed from the immediately following text. In these trim markers, the white space must be present: “{{- 3}}” is like “{{3}}” but trims the immediately preceding text, while “{{-3}}” parses as an action containing the number -3.

然而，为了帮助格式化模板源代码，如果一个操作的左定界符（默认为 “{{"）紧跟着一个减号和空格，那么紧随其后的所有尾部空格都会被从前面的文本中去除。类似地，如果右定界符（”}}"）之前有空格和减号，那么紧随其后的所有首部空格都会被从后面的文本中去除。在这些修剪标记中，空格必须存在："{{- 3}}" 类似于 “{{3}}"，但会去除紧随其前面的文本的空格，而 “{{-3}}” 解析为包含数字 -3 的操作。

For instance, when executing the template whose source is

例如，当执行源代码为以下模板时：

"{{23 -}} < {{- 45}}"

the generated output would be

生成的输出将会是：

"23<45"

For this trimming, the definition of white space characters is the same as in Go: space, horizontal tab, carriage return, and newline.

对于这种修剪操作，空格字符的定义与 Go 语言相同：空格、水平制表符、回车和换行符。

Actions 操作

Here is the list of actions. “Arguments” and “pipelines” are evaluations of data, defined in detail in the corresponding sections that follow.

以下是操作的列表。“参数"和"管道"是数据的评估，在接下来的相应章节中有详细定义。

{{/* a comment */}}
{{- /* a comment with white space trimmed from preceding and following text */ -}}
	A comment; discarded. May contain newlines.
	Comments do not nest and must start and end at the
	delimiters, as shown here.

{{pipeline}}
	The default textual representation (the same as would be
	printed by fmt.Print) of the value of the pipeline is copied
	to the output.

{{if pipeline}} T1 {{end}}
	If the value of the pipeline is empty, no output is generated;
	otherwise, T1 is executed. The empty values are false, 0, any
	nil pointer or interface value, and any array, slice, map, or
	string of length zero.
	Dot is unaffected.

{{if pipeline}} T1 {{else}} T0 {{end}}
	If the value of the pipeline is empty, T0 is executed;
	otherwise, T1 is executed. Dot is unaffected.

{{if pipeline}} T1 {{else if pipeline}} T0 {{end}}
	To simplify the appearance of if-else chains, the else action
	of an if may include another if directly; the effect is exactly
	the same as writing
		{{if pipeline}} T1 {{else}}{{if pipeline}} T0 {{end}}{{end}}

{{range pipeline}} T1 {{end}}
	The value of the pipeline must be an array, slice, map, or channel.
	If the value of the pipeline has length zero, nothing is output;
	otherwise, dot is set to the successive elements of the array,
	slice, or map and T1 is executed. If the value is a map and the
	keys are of basic type with a defined order, the elements will be
	visited in sorted key order.

{{range pipeline}} T1 {{else}} T0 {{end}}
	The value of the pipeline must be an array, slice, map, or channel.
	If the value of the pipeline has length zero, dot is unaffected and
	T0 is executed; otherwise, dot is set to the successive elements
	of the array, slice, or map and T1 is executed.

{{break}}
	The innermost {{range pipeline}} loop is ended early, stopping the
	current iteration and bypassing all remaining iterations.

{{continue}}
	The current iteration of the innermost {{range pipeline}} loop is
	stopped, and the loop starts the next iteration.

{{template "name"}}
	The template with the specified name is executed with nil data.

{{template "name" pipeline}}
	The template with the specified name is executed with dot set
	to the value of the pipeline.

{{block "name" pipeline}} T1 {{end}}
	A block is shorthand for defining a template
		{{define "name"}} T1 {{end}}
	and then executing it in place
		{{template "name" pipeline}}
	The typical use is to define a set of root templates that are
	then customized by redefining the block templates within.

{{with pipeline}} T1 {{end}}
	If the value of the pipeline is empty, no output is generated;
	otherwise, dot is set to the value of the pipeline and T1 is
	executed.

{{with pipeline}} T1 {{else}} T0 {{end}}
	If the value of the pipeline is empty, dot is unaffected and T0
	is executed; otherwise, dot is set to the value of the pipeline
	and T1 is executed.

Arguments 参数

An argument is a simple value, denoted by one of the following.

参数是一个简单的值，由以下之一表示。

• A boolean, string, character, integer, floating-point, imaginary or complex constant in Go syntax. These behave like Go’s untyped constants. Note that, as in Go, whether a large integer constant overflows when assigned or passed to a function can depend on whether the host machine’s ints are 32 or 64 bits.
• 一个布尔值、字符串、字符、整数、浮点数、虚数或复数常量，采用 Go 语法。它们的行为类似于 Go 的无类型常量。需要注意的是，与 Go 语言中一样，当大整数常量被赋值或传递给函数时，是否会溢出取决于主机机器的 int 类型是 32 位还是 64 位。
• The keyword nil, representing an untyped Go nil.
• 关键字 nil，表示无类型的 Go nil。
• The character ‘.’ (period): . The result is the value of dot.
• 字符 ‘.’（句点）：. 结果是 dot 的值。
• A variable name, which is a (possibly empty) alphanumeric string preceded by a dollar sign, such as $piOver2 or $ The result is the value of the variable. Variables are described below.
• 变量名，是一个（可能为空的）由美元符号前缀的字母数字字符串，例如 $piOver2 或 $。结果是变量的值。变量将在下面进行描述。
• The name of a field of the data, which must be a struct, preceded by a period, such as .Field The result is the value of the field. Field invocations may be chained: .Field1.Field2 Fields can also be evaluated on variables, including chaining: $x.Field1.Field2
• 数据的字段名，必须是一个结构体，由句点前缀，例如 .Field。结果是字段的值。字段调用可以链式调用：.Field1.Field2 字段还可以在变量上进行求值，包括链式调用：$x.Field1.Field2
• The name of a key of the data, which must be a map, preceded by a period, such as .Key The result is the map element value indexed by the key. Key invocations may be chained and combined with fields to any depth: .Field1.Key1.Field2.Key2 Although the key must be an alphanumeric identifier, unlike with field names they do not need to start with an upper case letter. Keys can also be evaluated on variables, including chaining: $x.key1.key2
• 数据的键名，必须是一个映射，由句点前缀，例如 .Key。结果是由键索引的映射元素的值。键调用可以链式调用，并与字段组合到任意深度：.Field1.Key1.Field2.Key2 尽管键必须是字母数字标识符，但与字段名不同，它们不需要以大写字母开头。键还可以在变量上进行求值，包括链式调用：$x.key1.key2
• The name of a niladic method of the data, preceded by a period, such as .Method The result is the value of invoking the method with dot as the receiver, dot.Method(). Such a method must have one return value (of any type) or two return values, the second of which is an error. If it has two and the returned error is non-nil, execution terminates and an error is returned to the caller as the value of Execute. Method invocations may be chained and combined with fields and keys to any depth: .Field1.Key1.Method1.Field2.Key2.Method2 Methods can also be evaluated on variables, including chaining: $x.Method1.Field
• 数据的零参数方法名称，由句点前缀，例如 .Method。结果是使用 dot 作为接收器调用方法的值，dot.Method()。这样的方法必须具有一个返回值（任意类型）或两个返回值，第二个返回值是一个错误。如果有两个返回值且返回的错误非空，则执行终止，并将错误作为 Execute 的返回值返回给调用者。方法调用可以链式调用，并与字段和键组合到任意深度：.Field1.Key1.Method1.Field2.Key2.Method2 方法还可以在变量上进行求值，包括链式调用：$x.Method1.Field
• The name of a niladic function, such as fun The result is the value of invoking the function, fun(). The return types and values behave as in methods. Functions and function names are described below.
• 无参数函数的名称，例如 fun。结果是调用函数的值，fun()。返回类型和值的行为与方法相同。函数和函数名将在下面进行描述。
• A parenthesized instance of one the above, for grouping. The result may be accessed by a field or map key invocation. print (.F1 arg1) (.F2 arg2) (.StructValuedMethod “arg”).Field
• 上述内容的括号实例，用于分组。结果可以通过字段或映射键调用进行访问。print (.F1 arg1) (.F2 arg2) (.StructValuedMethod “arg”).Field

Arguments may evaluate to any type; if they are pointers the implementation automatically indirects to the base type when required. If an evaluation yields a function value, such as a function-valued field of a struct, the function is not invoked automatically, but it can be used as a truth value for an if action and the like. To invoke it, use the call function, defined below.

参数可以评估为任何类型；如果它们是指针，则在需要时实现会自动间接引用到基本类型。如果评估结果是一个函数值，例如结构体的函数值字段，函数不会自动调用，但可以用作 if 动作等的真值。要调用它，使用下面定义的 call 函数。

Pipelines 管道

A pipeline is a possibly chained sequence of “commands”. A command is a simple value (argument) or a function or method call, possibly with multiple arguments:

管道是一个可能被链式组合的"命令"序列。命令可以是一个简单的值（参数）或一个函数或方法调用，可能带有多个参数：

Argument
	The result is the value of evaluating the argument.
.Method [Argument...]
	The method can be alone or the last element of a chain but,
	unlike methods in the middle of a chain, it can take arguments.
	The result is the value of calling the method with the
	arguments:
		dot.Method(Argument1, etc.)
functionName [Argument...]
	The result is the value of calling the function associated
	with the name:
		function(Argument1, etc.)
	Functions and function names are described below.

A pipeline may be “chained” by separating a sequence of commands with pipeline characters ‘|’. In a chained pipeline, the result of each command is passed as the last argument of the following command. The output of the final command in the pipeline is the value of the pipeline.

通过使用管道字符 ‘|’ 将一系列命令连接起来，可以"链式"组合管道。在链式管道中，每个命令的结果都作为下一个命令的最后一个参数传递。管道中最后一个命令的输出是管道的值。

The output of a command will be either one value or two values, the second of which has type error. If that second value is present and evaluates to non-nil, execution terminates and the error is returned to the caller of Execute.

命令的输出将是一个值或两个值，其中第二个值的类型为 error。如果第二个值存在且评估为非空，则执行终止，并将错误返回给 Execute 的调用者。

变量

A pipeline inside an action may initialize a variable to capture the result. The initialization has syntax

在动作中的管道中可以初始化一个变量来捕获结果。初始化的语法如下：

$variable := pipeline

where $variable is the name of the variable. An action that declares a variable produces no output.

其中 $variable 是变量的名称。声明变量的动作不会产生输出。

Variables previously declared can also be assigned, using the syntax

之前声明的变量也可以赋值，使用的语法是：

$variable = pipeline

If a “range” action initializes a variable, the variable is set to the successive elements of the iteration. Also, a “range” may declare two variables, separated by a comma:

如果"range"动作初始化了一个变量，该变量将被设置为迭代的连续元素。此外，“range"还可以声明两个变量，用逗号分隔：

range $index, $element := pipeline

in which case $index and $element are set to the successive values of the array/slice index or map key and element, respectively. Note that if there is only one variable, it is assigned the element; this is opposite to the convention in Go range clauses.

在这种情况下，$index 和 $element 分别设置为数组/切片索引或映射键和元素的连续值。请注意，如果只有一个变量，它将被赋值为元素；这与 Go range 语句的惯例相反。

A variable’s scope extends to the “end” action of the control structure (“if”, “with”, or “range”) in which it is declared, or to the end of the template if there is no such control structure. A template invocation does not inherit variables from the point of its invocation.

变量的作用域延伸到控制结构（“if”、“with” 或 “range”）的 “end” 动作，或者如果没有这样的控制结构，则延伸到模板的末尾。模板调用不会继承从调用点传递的变量。

When execution begins, $ is set to the data argument passed to Execute, that is, to the starting value of dot.

当执行开始时，$ 设置为传递给 Execute 的数据参数，即 dot 的初始值。

Here are some example one-line templates demonstrating pipelines and variables. All produce the quoted word “output”:

以下是一些示例的一行模板，演示了管道和变量。它们都会产生引号中的单词 “output”。

{{"\"output\""}}
	A string constant.
{{`"output"`}}
	A raw string constant.
{{printf "%q" "output"}}
	A function call.
{{"output" | printf "%q"}}
	A function call whose final argument comes from the previous
	command.
{{printf "%q" (print "out" "put")}}
	A parenthesized argument.
{{"put" | printf "%s%s" "out" | printf "%q"}}
	A more elaborate call.
{{"output" | printf "%s" | printf "%q"}}
	A longer chain.
{{with "output"}}{{printf "%q" .}}{{end}}
	A with action using dot.
{{with $x := "output" | printf "%q"}}{{$x}}{{end}}
	A with action that creates and uses a variable.
{{with $x := "output"}}{{printf "%q" $x}}{{end}}
	A with action that uses the variable in another action.
{{with $x := "output"}}{{$x | printf "%q"}}{{end}}
	The same, but pipelined.

函数

During execution functions are found in two function maps: first in the template, then in the global function map. By default, no functions are defined in the template but the Funcs method can be used to add them.

在执行过程中，函数可以在两个函数映射中找到：首先在模板中，然后在全局函数映射中。默认情况下，模板中没有定义函数，但可以使用 Funcs 方法来添加函数。

Predefined global functions are named as follows.

预定义的全局函数的名称如下所示。

and
	Returns the boolean AND of its arguments by returning the
	first empty argument or the last argument. That is,
	"and x y" behaves as "if x then y else x."
	Evaluation proceeds through the arguments left to right
	and returns when the result is determined.
call
	Returns the result of calling the first argument, which
	must be a function, with the remaining arguments as parameters.
	Thus "call .X.Y 1 2" is, in Go notation, dot.X.Y(1, 2) where
	Y is a func-valued field, map entry, or the like.
	The first argument must be the result of an evaluation
	that yields a value of function type (as distinct from
	a predefined function such as print). The function must
	return either one or two result values, the second of which
	is of type error. If the arguments don't match the function
	or the returned error value is non-nil, execution stops.
html
	Returns the escaped HTML equivalent of the textual
	representation of its arguments. This function is unavailable
	in html/template, with a few exceptions.
index
	Returns the result of indexing its first argument by the
	following arguments. Thus "index x 1 2 3" is, in Go syntax,
	x[1][2][3]. Each indexed item must be a map, slice, or array.
slice
	slice returns the result of slicing its first argument by the
	remaining arguments. Thus "slice x 1 2" is, in Go syntax, x[1:2],
	while "slice x" is x[:], "slice x 1" is x[1:], and "slice x 1 2 3"
	is x[1:2:3]. The first argument must be a string, slice, or array.
js
	Returns the escaped JavaScript equivalent of the textual
	representation of its arguments.
len
	Returns the integer length of its argument.
not
	Returns the boolean negation of its single argument.
or
	Returns the boolean OR of its arguments by returning the
	first non-empty argument or the last argument, that is,
	"or x y" behaves as "if x then x else y".
	Evaluation proceeds through the arguments left to right
	and returns when the result is determined.
print
	An alias for fmt.Sprint
printf
	An alias for fmt.Sprintf
println
	An alias for fmt.Sprintln
urlquery
	Returns the escaped value of the textual representation of
	its arguments in a form suitable for embedding in a URL query.
	This function is unavailable in html/template, with a few
	exceptions.

The boolean functions take any zero value to be false and a non-zero value to be true.

布尔函数将任何零值视为 false，非零值视为 true。

There is also a set of binary comparison operators defined as functions:

还有一组作为函数定义的二元比较运算符：

eq
	Returns the boolean truth of arg1 == arg2
ne
	Returns the boolean truth of arg1 != arg2
lt
	Returns the boolean truth of arg1 < arg2
le
	Returns the boolean truth of arg1 <= arg2
gt
	Returns the boolean truth of arg1 > arg2
ge
	Returns the boolean truth of arg1 >= arg2

For simpler multi-way equality tests, eq (only) accepts two or more arguments and compares the second and subsequent to the first, returning in effect

对于更简单的多路相等性测试，eq（仅限）接受两个或多个参数，并将第二个及后续参数与第一个参数进行比较，实际上返回

arg1==arg2 || arg1==arg3 || arg1==arg4 ...

(Unlike with || in Go, however, eq is a function call and all the arguments will be evaluated.)

（与 Go 中的 || 不同，eq 是一个函数调用，所有参数都将被评估。）

The comparison functions work on any values whose type Go defines as comparable. For basic types such as integers, the rules are relaxed: size and exact type are ignored, so any integer value, signed or unsigned, may be compared with any other integer value. (The arithmetic value is compared, not the bit pattern, so all negative integers are less than all unsigned integers.) However, as usual, one may not compare an int with a float32 and so on.

比较函数适用于 Go 定义为可比较的任何值。对于基本类型（例如整数），规则放宽：大小和确切类型被忽略，因此任何整数值（有符号或无符号）可以与任何其他整数值进行比较。（比较的是算术值，而不是位模式，因此所有负整数都小于所有无符号整数。）但是，通常情况下，不能将 int 与 float32 等进行比较。

Associated templates 关联模板

Each template is named by a string specified when it is created. Also, each template is associated with zero or more other templates that it may invoke by name; such associations are transitive and form a name space of templates.

每个模板都由一个在创建时指定的字符串命名。此外，每个模板与零个或多个其他模板相关联，可以通过名称调用它们；这种关联是传递性的，并形成模板的名称空间。

A template may use a template invocation to instantiate another associated template; see the explanation of the “template” action above. The name must be that of a template associated with the template that contains the invocation.

模板可以使用模板调用来实例化另一个关联的模板；请参阅上面关于 “template” 动作的说明。名称必须是与包含调用的模板关联的模板名称。

Nested template definitions 嵌套模板定义

When parsing a template, another template may be defined and associated with the template being parsed. Template definitions must appear at the top level of the template, much like global variables in a Go program.

在解析模板时，可以定义另一个模板并将其与正在解析的模板相关联。模板定义必须出现在模板的顶层，就像在 Go 程序中的全局变量一样。

The syntax of such definitions is to surround each template declaration with a “define” and “end” action.

这种定义的语法是用 “define” 和 “end” 动作括起来的每个模板声明。

The define action names the template being created by providing a string constant. Here is a simple example:

define 动作通过提供一个字符串常量来为正在创建的模板命名。下面是一个简单的示例：

{{define "T1"}}ONE{{end}}
{{define "T2"}}TWO{{end}}
{{define "T3"}}{{template "T1"}} {{template "T2"}}{{end}}
{{template "T3"}}

This defines two templates, T1 and T2, and a third T3 that invokes the other two when it is executed. Finally it invokes T3. If executed this template will produce the text

这定义了两个模板，T1 和 T2，以及一个在执行时调用其他两个模板的 T3。最后，它调用了 T3。如果执行这个模板，将会产生文本：

ONE TWO

By construction, a template may reside in only one association. If it’s necessary to have a template addressable from multiple associations, the template definition must be parsed multiple times to create distinct *Template values, or must be copied with the Clone or AddParseTree method.

按照设计，一个模板只能存在于一个关联中。如果需要将一个模板从多个关联中访问，模板定义必须被多次解析以创建不同的 *Template 值，或者必须使用 Clone 或 AddParseTree 方法进行复制。

Parse may be called multiple times to assemble the various associated templates; see the ParseFiles and ParseGlob functions and methods for simple ways to parse related templates stored in files.

可以多次调用 Parse 来组装各个关联的模板；可以使用 ParseFiles 和 ParseGlob 函数和方法来解析存储在文件中的相关模板的简单方法。

A template may be executed directly or through ExecuteTemplate, which executes an associated template identified by name. To invoke our example above, we might write,

模板可以直接执行，也可以通过 ExecuteTemplate 来执行，后者根据名称执行一个关联的模板。为了调用上面的示例，我们可以编写如下代码：

err := tmpl.Execute(os.Stdout, "no data needed")
if err != nil {
	log.Fatalf("execution failed: %s", err)
}

or to invoke a particular template explicitly by name,

或者通过名称显式地调用特定的模板：

err := tmpl.ExecuteTemplate(os.Stdout, "T2", "no data needed")
if err != nil {
	log.Fatalf("execution failed: %s", err)
}

常量

This section is empty.

变量

This section is empty.

函数

func HTMLEscape

1

func HTMLEscape(w io.Writer, b []byte)

HTMLEscape writes to w the escaped HTML equivalent of the plain text data b.

HTMLEscape 函数将纯文本数据 b 的 HTML 转义写入 w。

func HTMLEscapeString

1

func HTMLEscapeString(s string) string

HTMLEscapeString returns the escaped HTML equivalent of the plain text data s.

HTMLEscapeString 函数返回纯文本数据 s 的转义 HTML。

func HTMLEscaper

1

func HTMLEscaper(args ...any) string

HTMLEscaper returns the escaped HTML equivalent of the textual representation of its arguments.

HTMLEscaper 函数返回其参数文本表示的转义 HTML。

func IsTrue <- go1.6

1

func IsTrue(val any) (truth, ok bool)

IsTrue reports whether the value is ’true’, in the sense of not the zero of its type, and whether the value has a meaningful truth value. This is the definition of truth used by if and other such actions.

IsTrue 函数报告值是否为"true”，即不是其类型的零值，并且该值具有有意义的真值。这是 if 和其他类似操作使用的真值定义。

func JSEscape

1

func JSEscape(w io.Writer, b []byte)

JSEscape writes to w the escaped JavaScript equivalent of the plain text data b.

JSEscape 函数将纯文本数据 b 的 JavaScript 转义写入 w。

func JSEscapeString

1

func JSEscapeString(s string) string

JSEscapeString returns the escaped JavaScript equivalent of the plain text data s.

JSEscapeString 函数返回纯文本数据 s 的转义 JavaScript。

func JSEscaper

1

func JSEscaper(args ...any) string

JSEscaper returns the escaped JavaScript equivalent of the textual representation of its arguments.

JSEscaper 函数返回其参数文本表示的转义 JavaScript。

func URLQueryEscaper

1

func URLQueryEscaper(args ...any) string

URLQueryEscaper returns the escaped value of the textual representation of its arguments in a form suitable for embedding in a URL query.

URLQueryEscaper函数返回其参数文本表示的转义值，适用于嵌入到 URL 查询中。

类型

type ExecError <- go1.6

1
2
3
4

type ExecError struct {
	Name string // Name of template.
	Err  error  // Pre-formatted error.
}

ExecError is the custom error type returned when Execute has an error evaluating its template. (If a write error occurs, the actual error is returned; it will not be of type ExecError.)

ExecError 是在执行模板时发生错误时返回的自定义错误类型。（如果发生写入错误，则返回实际错误；它不会是 ExecError 类型。）

(ExecError) Error <- go1.6

1

func (e ExecError) Error() string

(ExecError) Unwrap <- go1.13

1

func (e ExecError) Unwrap() error

type FuncMap

1

type FuncMap map[string]any

FuncMap is the type of the map defining the mapping from names to functions. Each function must have either a single return value, or two return values of which the second has type error. In that case, if the second (error) return value evaluates to non-nil during execution, execution terminates and Execute returns that error.

FuncMap 是定义从名称到函数的映射的映射类型。每个函数必须具有单个返回值或两个返回值，其中第二个返回值的类型为 error。在执行过程中，如果第二个（error）返回值求值为非 nil，则执行终止，并且 Execute 返回该错误。

Errors returned by Execute wrap the underlying error; call errors.As to uncover them.

Execute 返回的错误会包装底层错误；可以使用 errors.As 解析它们。

When template execution invokes a function with an argument list, that list must be assignable to the function’s parameter types. Functions meant to apply to arguments of arbitrary type can use parameters of type interface{} or of type reflect.Value. Similarly, functions meant to return a result of arbitrary type can return interface{} or reflect.Value.

当模板执行调用带有参数列表的函数时，该列表必须可赋值给函数的参数类型。用于适用于任意类型参数的函数可以使用类型 interface{} 或 reflect.Value 的参数。类似地，用于返回任意类型结果的函数可以返回 interface{} 或 reflect.Value。

type Template

1
2
3
4

type Template struct {
	*parse.Tree
	// contains filtered or unexported fields
}

Template is the representation of a parsed template. The *parse.Tree field is exported only for use by html/template and should be treated as unexported by all other clients.

Template 是解析模板的表示形式。*parse.Tree 字段只对 html/template 使用者公开，对于其他所有客户端，应将其视为未公开。

Template Example

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72

package main

import (
	"log"
	"os"
	"text/template"
)

func main() {
	// Define a template.
	const letter = `
Dear {{.Name}},
{{if .Attended}}
It was a pleasure to see you at the wedding.
{{- else}}
It is a shame you couldn't make it to the wedding.
{{- end}}
{{with .Gift -}}
Thank you for the lovely {{.}}.
{{end}}
Best wishes,
Josie
`

	// Prepare some data to insert into the template.
	type Recipient struct {
		Name, Gift string
		Attended   bool
	}
	var recipients = []Recipient{
		{"Aunt Mildred", "bone china tea set", true},
		{"Uncle John", "moleskin pants", false},
		{"Cousin Rodney", "", false},
	}

	// Create a new template and parse the letter into it.
	t := template.Must(template.New("letter").Parse(letter))

	// Execute the template for each recipient.
	for _, r := range recipients {
		err := t.Execute(os.Stdout, r)
		if err != nil {
			log.Println("executing template:", err)
		}
	}

}

Output:

Dear Aunt Mildred,

It was a pleasure to see you at the wedding.
Thank you for the lovely bone china tea set.

Best wishes,
Josie

Dear Uncle John,

It is a shame you couldn't make it to the wedding.
Thank you for the lovely moleskin pants.

Best wishes,
Josie

Dear Cousin Rodney,

It is a shame you couldn't make it to the wedding.

Best wishes,
Josie

Template Example (Block)

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43

package main

import (
	"log"
	"os"
	"strings"
	"text/template"
)

func main() {
	const (
		master  = `Names:{{block "list" .}}{{"\n"}}{{range .}}{{println "-" .}}{{end}}{{end}}`
		overlay = `{{define "list"}} {{join . ", "}}{{end}} `
	)
	var (
		funcs     = template.FuncMap{"join": strings.Join}
		guardians = []string{"Gamora", "Groot", "Nebula", "Rocket", "Star-Lord"}
	)
	masterTmpl, err := template.New("master").Funcs(funcs).Parse(master)
	if err != nil {
		log.Fatal(err)
	}
	overlayTmpl, err := template.Must(masterTmpl.Clone()).Parse(overlay)
	if err != nil {
		log.Fatal(err)
	}
	if err := masterTmpl.Execute(os.Stdout, guardians); err != nil {
		log.Fatal(err)
	}
	if err := overlayTmpl.Execute(os.Stdout, guardians); err != nil {
		log.Fatal(err)
	}
}

Output:

Names:
- Gamora
- Groot
- Nebula
- Rocket
- Star-Lord
Names: Gamora, Groot, Nebula, Rocket, Star-Lord

Template Example (Func)

This example demonstrates a custom function to process template text. It installs the strings.Title function and uses it to Make Title Text Look Good In Our Template’s Output.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49

package main

import (
	"log"
	"os"
	"strings"
	"text/template"
)

func main() {
	// First we create a FuncMap with which to register the function.
	funcMap := template.FuncMap{
		// The name "title" is what the function will be called in the template text.
		"title": strings.Title,
	}

	// A simple template definition to test our function.
	// We print the input text several ways:
	// - the original
	// - title-cased
	// - title-cased and then printed with %q
	// - printed with %q and then title-cased.
	const templateText = `
Input: {{printf "%q" .}}
Output 0: {{title .}}
Output 1: {{title . | printf "%q"}}
Output 2: {{printf "%q" . | title}}
`

	// Create a template, add the function map, and parse the text.
	tmpl, err := template.New("titleTest").Funcs(funcMap).Parse(templateText)
	if err != nil {
		log.Fatalf("parsing: %s", err)
	}

	// Run the template to verify the output.
	err = tmpl.Execute(os.Stdout, "the go programming language")
	if err != nil {
		log.Fatalf("execution: %s", err)
	}

}

Output:

Input: "the go programming language"
Output 0: The Go Programming Language
Output 1: "The Go Programming Language"
Output 2: "The Go Programming Language"

Template Example(Glob)

Here we demonstrate loading a set of templates from a directory.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67

package main

import (
	"io"
	"log"
	"os"
	"path/filepath"
	"text/template"
)

// templateFile defines the contents of a template to be stored in a file, for testing.
type templateFile struct {
	name     string
	contents string
}

func createTestDir(files []templateFile) string {
	dir, err := os.MkdirTemp("", "template")
	if err != nil {
		log.Fatal(err)
	}
	for _, file := range files {
		f, err := os.Create(filepath.Join(dir, file.name))
		if err != nil {
			log.Fatal(err)
		}
		defer f.Close()
		_, err = io.WriteString(f, file.contents)
		if err != nil {
			log.Fatal(err)
		}
	}
	return dir
}

func main() {
	// Here we create a temporary directory and populate it with our sample
	// template definition files; usually the template files would already
	// exist in some location known to the program.
	dir := createTestDir([]templateFile{
		// T0.tmpl is a plain template file that just invokes T1.
		{"T0.tmpl", `T0 invokes T1: ({{template "T1"}})`},
		// T1.tmpl defines a template, T1 that invokes T2.
		{"T1.tmpl", `{{define "T1"}}T1 invokes T2: ({{template "T2"}}){{end}}`},
		// T2.tmpl defines a template T2.
		{"T2.tmpl", `{{define "T2"}}This is T2{{end}}`},
	})
	// Clean up after the test; another quirk of running as an example.
	defer os.RemoveAll(dir)

	// pattern is the glob pattern used to find all the template files.
	pattern := filepath.Join(dir, "*.tmpl")

	// Here starts the example proper.
	// T0.tmpl is the first name matched, so it becomes the starting template,
	// the value returned by ParseGlob.
	tmpl := template.Must(template.ParseGlob(pattern))

	err := tmpl.Execute(os.Stdout, nil)
	if err != nil {
		log.Fatalf("template execution: %s", err)
	}
}

Output:

T0 invokes T1: (T1 invokes T2: (This is T2))

Template Example (Helpers)

This example demonstrates one way to share some templates and use them in different contexts. In this variant we add multiple driver templates by hand to an existing bundle of templates.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80

package main

import (
	"io"
	"log"
	"os"
	"path/filepath"
	"text/template"
)

// templateFile defines the contents of a template to be stored in a file, for testing.
type templateFile struct {
	name     string
	contents string
}

func createTestDir(files []templateFile) string {
	dir, err := os.MkdirTemp("", "template")
	if err != nil {
		log.Fatal(err)
	}
	for _, file := range files {
		f, err := os.Create(filepath.Join(dir, file.name))
		if err != nil {
			log.Fatal(err)
		}
		defer f.Close()
		_, err = io.WriteString(f, file.contents)
		if err != nil {
			log.Fatal(err)
		}
	}
	return dir
}

func main() {
	// Here we create a temporary directory and populate it with our sample
	// template definition files; usually the template files would already
	// exist in some location known to the program.
	dir := createTestDir([]templateFile{
		// T1.tmpl defines a template, T1 that invokes T2.
		{"T1.tmpl", `{{define "T1"}}T1 invokes T2: ({{template "T2"}}){{end}}`},
		// T2.tmpl defines a template T2.
		{"T2.tmpl", `{{define "T2"}}This is T2{{end}}`},
	})
	// Clean up after the test; another quirk of running as an example.
	defer os.RemoveAll(dir)

	// pattern is the glob pattern used to find all the template files.
	pattern := filepath.Join(dir, "*.tmpl")

	// Here starts the example proper.
	// Load the helpers.
	templates := template.Must(template.ParseGlob(pattern))
	// Add one driver template to the bunch; we do this with an explicit template definition.
	_, err := templates.Parse("{{define `driver1`}}Driver 1 calls T1: ({{template `T1`}})\n{{end}}")
	if err != nil {
		log.Fatal("parsing driver1: ", err)
	}
	// Add another driver template.
	_, err = templates.Parse("{{define `driver2`}}Driver 2 calls T2: ({{template `T2`}})\n{{end}}")
	if err != nil {
		log.Fatal("parsing driver2: ", err)
	}
	// We load all the templates before execution. This package does not require
	// that behavior but html/template's escaping does, so it's a good habit.
	err = templates.ExecuteTemplate(os.Stdout, "driver1", nil)
	if err != nil {
		log.Fatalf("driver1 execution: %s", err)
	}
	err = templates.ExecuteTemplate(os.Stdout, "driver2", nil)
	if err != nil {
		log.Fatalf("driver2 execution: %s", err)
	}
}

Output:

Driver 1 calls T1: (T1 invokes T2: (This is T2))
Driver 2 calls T2: (This is T2)

Template Example (Share)

This example demonstrates how to use one group of driver templates with distinct sets of helper templates.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98

package main

import (
	"io"
	"log"
	"os"
	"path/filepath"
	"text/template"
)

// templateFile defines the contents of a template to be stored in a file, for testing.
type templateFile struct {
	name     string
	contents string
}

func createTestDir(files []templateFile) string {
	dir, err := os.MkdirTemp("", "template")
	if err != nil {
		log.Fatal(err)
	}
	for _, file := range files {
		f, err := os.Create(filepath.Join(dir, file.name))
		if err != nil {
			log.Fatal(err)
		}
		defer f.Close()
		_, err = io.WriteString(f, file.contents)
		if err != nil {
			log.Fatal(err)
		}
	}
	return dir
}

func main() {
	// Here we create a temporary directory and populate it with our sample
	// template definition files; usually the template files would already
	// exist in some location known to the program.
	dir := createTestDir([]templateFile{
		// T0.tmpl is a plain template file that just invokes T1.
		{"T0.tmpl", "T0 ({{.}} version) invokes T1: ({{template `T1`}})\n"},
		// T1.tmpl defines a template, T1 that invokes T2. Note T2 is not defined
		{"T1.tmpl", `{{define "T1"}}T1 invokes T2: ({{template "T2"}}){{end}}`},
	})
	// Clean up after the test; another quirk of running as an example.
	defer os.RemoveAll(dir)

	// pattern is the glob pattern used to find all the template files.
	pattern := filepath.Join(dir, "*.tmpl")

	// Here starts the example proper.
	// Load the drivers.
	drivers := template.Must(template.ParseGlob(pattern))

	// We must define an implementation of the T2 template. First we clone
	// the drivers, then add a definition of T2 to the template name space.

	// 1. Clone the helper set to create a new name space from which to run them.
	first, err := drivers.Clone()
	if err != nil {
		log.Fatal("cloning helpers: ", err)
	}
	// 2. Define T2, version A, and parse it.
	_, err = first.Parse("{{define `T2`}}T2, version A{{end}}")
	if err != nil {
		log.Fatal("parsing T2: ", err)
	}

	// Now repeat the whole thing, using a different version of T2.
	// 1. Clone the drivers.
	second, err := drivers.Clone()
	if err != nil {
		log.Fatal("cloning drivers: ", err)
	}
	// 2. Define T2, version B, and parse it.
	_, err = second.Parse("{{define `T2`}}T2, version B{{end}}")
	if err != nil {
		log.Fatal("parsing T2: ", err)
	}

	// Execute the templates in the reverse order to verify the
	// first is unaffected by the second.
	err = second.ExecuteTemplate(os.Stdout, "T0.tmpl", "second")
	if err != nil {
		log.Fatalf("second execution: %s", err)
	}
	err = first.ExecuteTemplate(os.Stdout, "T0.tmpl", "first")
	if err != nil {
		log.Fatalf("first: execution: %s", err)
	}

}

Output:

T0 (second version) invokes T1: (T1 invokes T2: (T2, version B))
T0 (first version) invokes T1: (T1 invokes T2: (T2, version A))

func Must

1

func Must(t *Template, err error) *Template

Must is a helper that wraps a call to a function returning (*Template, error) and panics if the error is non-nil. It is intended for use in variable initializations such as

Must 是一个辅助函数，用于包装返回 (*Template, error) 的函数调用，如果错误非 nil，则引发 panic。它适用于变量初始化，例如：

1

var t = template.Must(template.New("name").Parse("text"))

func New

1

func New(name string) *Template

New allocates a new, undefined template with the given name.

New 分配一个具有给定名称的新的未定义模板。

func ParseFS <- go1.16

1

func ParseFS(fsys fs.FS, patterns ...string) (*Template, error)

ParseFS is like ParseFiles or ParseGlob but reads from the file system fsys instead of the host operating system’s file system. It accepts a list of glob patterns. (Note that most file names serve as glob patterns matching only themselves.)

ParseFS 类似于 ParseFiles 或 ParseGlob，但是从文件系统 fsys 而不是主机操作系统的文件系统中读取。它接受一个 glob 模式的列表。（注意，大多数文件名本身都作为仅匹配自身的 glob 模式。）

func ParseFiles

1

func ParseFiles(filenames ...string) (*Template, error)

ParseFiles creates a new Template and parses the template definitions from the named files. The returned template’s name will have the base name and parsed contents of the first file. There must be at least one file. If an error occurs, parsing stops and the returned *Template is nil.

ParseFiles 创建一个新的 Template，并从指定的文件中解析模板定义。返回的模板的名称将使用第一个文件的基本名称和解析内容。至少必须有一个文件。如果发生错误，解析将停止，返回的 *Template 为 nil。

When parsing multiple files with the same name in different directories, the last one mentioned will be the one that results. For instance, ParseFiles(“a/foo”, “b/foo”) stores “b/foo” as the template named “foo”, while “a/foo” is unavailable.

当解析具有相同名称但位于不同目录中的多个文件时，结果将是最后一个被提及的文件。例如，ParseFiles(“a/foo”, “b/foo”) 将使用名称为 “foo” 的模板存储 “b/foo”，而 “a/foo” 将无法使用。

func ParseGlob

1

func ParseGlob(pattern string) (*Template, error)

ParseGlob creates a new Template and parses the template definitions from the files identified by the pattern. The files are matched according to the semantics of filepath.Match, and the pattern must match at least one file. The returned template will have the (base) name and (parsed) contents of the first file matched by the pattern. ParseGlob is equivalent to calling ParseFiles with the list of files matched by the pattern.

ParseGlob 创建一个新的 Template，并从与模式匹配的文件中解析模板定义。文件的匹配根据 filepath.Match 的语义进行，模式必须至少匹配一个文件。返回的模板将使用与模式匹配的第一个文件的（基本）名称和（解析的）内容。ParseGlob 等效于使用模式匹配的文件列表调用 ParseFiles。

When parsing multiple files with the same name in different directories, the last one mentioned will be the one that results.

当解析具有相同名称但位于不同目录中的多个文件时，结果将是最后一个被提及的文件。

(*Template) AddParseTree

1

func (t *Template) AddParseTree(name string, tree *parse.Tree) (*Template, error)

AddParseTree associates the argument parse tree with the template t, giving it the specified name. If the template has not been defined, this tree becomes its definition. If it has been defined and already has that name, the existing definition is replaced; otherwise a new template is created, defined, and returned.

AddParseTree 将传入的解析树与模板 t 关联，并指定名称。如果模板尚未定义，则该解析树成为其定义。如果已经定义并且具有相同的名称，则替换现有的定义；否则，创建、定义并返回一个新的模板。

(*Template) Clone

1

func (t *Template) Clone() (*Template, error)

Clone returns a duplicate of the template, including all associated templates. The actual representation is not copied, but the name space of associated templates is, so further calls to Parse in the copy will add templates to the copy but not to the original. Clone can be used to prepare common templates and use them with variant definitions for other templates by adding the variants after the clone is made.

Clone 返回模板的副本，包括所有关联的模板。实际的表示形式不会被复制，但关联模板的名称空间会被复制，因此在副本中对 Parse 的进一步调用将向副本添加模板，而不是添加到原始模板。可以使用 Clone 来准备常用模板，并使用变体定义的其他模板，通过在克隆完成后添加变体。

(*Template) DefinedTemplates <- go1.5

1

func (t *Template) DefinedTemplates() string

DefinedTemplates returns a string listing the defined templates, prefixed by the string “; defined templates are: “. If there are none, it returns the empty string. For generating an error message here and in html/template.

DefinedTemplates 返回一个以字符串 “; defined templates are: " 为前缀的已定义模板列表。如果没有模板，则返回空字符串。用于在此处和 html/template 中生成错误消息。

(*Template) Delims

1

func (t *Template) Delims(left, right string) *Template

Delims sets the action delimiters to the specified strings, to be used in subsequent calls to Parse, ParseFiles, or ParseGlob. Nested template definitions will inherit the settings. An empty delimiter stands for the corresponding default: {{ or }}. The return value is the template, so calls can be chained.

Delims 将动作定界符设置为指定的字符串，以在后续对 Parse、ParseFiles 或 ParseGlob 的调用中使用。嵌套模板定义将继承这些设置。空定界符表示对应的默认值：{{ 或 }}。返回值是模板本身，因此可以链式调用。

(*Template) Execute

1

func (t *Template) Execute(wr io.Writer, data any) error

Execute applies a parsed template to the specified data object, and writes the output to wr. If an error occurs executing the template or writing its output, execution stops, but partial results may already have been written to the output writer. A template may be executed safely in parallel, although if parallel executions share a Writer the output may be interleaved.

Execute 将解析的模板应用于指定的数据对象，并将输出写入 wr。如果在执行模板或写入输出时发生错误，执行将停止，但部分结果可能已经写入输出写入器。模板可以在并行安全地执行，但如果并行执行共享一个 Writer，则输出可能会交错。

If data is a reflect.Value, the template applies to the concrete value that the reflect.Value holds, as in fmt.Print.

如果 data 是 reflect.Value，则模板应用于 reflect.Value 持有的具体值，就像 fmt.Print 一样。

(*Template) ExecuteTemplate

1

func (t *Template) ExecuteTemplate(wr io.Writer, name string, data any) error

ExecuteTemplate applies the template associated with t that has the given name to the specified data object and writes the output to wr. If an error occurs executing the template or writing its output, execution stops, but partial results may already have been written to the output writer. A template may be executed safely in parallel, although if parallel executions share a Writer the output may be interleaved.

ExecuteTemplate 将与 t 关联且具有给定名称的模板应用于指定的数据对象，并将输出写入 wr。如果在执行模板或写入输出时发生错误，执行将停止，但部分结果可能已经写入输出写入器。模板可以在并行安全地执行，但如果并行执行共享一个 Writer，则输出可能会交错。

(*Template) Funcs

1

func (t *Template) Funcs(funcMap FuncMap) *Template

Funcs adds the elements of the argument map to the template’s function map. It must be called before the template is parsed. It panics if a value in the map is not a function with appropriate return type or if the name cannot be used syntactically as a function in a template. It is legal to overwrite elements of the map. The return value is the template, so calls can be chained.

Funcs 将参数映射的元素添加到模板的函数映射中。必须在解析模板之前调用。如果映射中的值不是具有适当返回类型的函数，或者名称在模板中不能作为函数使用，则会引发 panic。可以覆盖映射的元素。返回值是模板本身，因此可以链式调用。

(*Template) Lookup

1

func (t *Template) Lookup(name string) *Template

Lookup returns the template with the given name that is associated with t. It returns nil if there is no such template or the template has no definition.

Lookup 返回与 t 关联且具有给定名称的模板。如果没有这样的模板或模板没有定义，则返回 nil。

(*Template) Name

1

func (t *Template) Name() string

Name returns the name of the template.

Name 返回模板的名称。

(*Template) New

1

func (t *Template) New(name string) *Template

New allocates a new, undefined template associated with the given one and with the same delimiters. The association, which is transitive, allows one template to invoke another with a {{template}} action.

New 分配一个新的未定义模板，并与给定模板关联，并具有相同的分隔符。关联关系是传递的，允许一个模板使用 {{template}} 操作调用另一个模板。

Because associated templates share underlying data, template construction cannot be done safely in parallel. Once the templates are constructed, they can be executed in parallel.

由于关联模板共享底层数据，模板构建不能并行安全地进行。一旦模板构建完成，它们可以并行执行。

(*Template) Option <- go1.5

1

func (t *Template) Option(opt ...string) *Template

Option sets options for the template. Options are described by strings, either a simple string or “key=value”. There can be at most one equals sign in an option string. If the option string is unrecognized or otherwise invalid, Option panics.

Option 为模板设置选项。选项由字符串描述，可以是简单字符串或 “key=value” 形式。选项字符串中最多只能有一个等号。如果选项字符串未被识别或无效，则 Option 会引发 panic。

Known options:

已知选项：

missingkey: Control the behavior during execution if a map is indexed with a key that is not present in the map.

missingkey: 控制在执行过程中，如果使用在映射中不存在的键对映射进行索引的行为。

"missingkey=default" or "missingkey=invalid"
	The default behavior: Do nothing and continue execution.
	If printed, the result of the index operation is the string
	"<no value>".
"missingkey=zero"
	The operation returns the zero value for the map type's element.
"missingkey=error"
	Execution stops immediately with an error.

(*Template) Parse

1

func (t *Template) Parse(text string) (*Template, error)

Parse parses text as a template body for t. Named template definitions ({{define …}} or {{block …}} statements) in text define additional templates associated with t and are removed from the definition of t itself.

Parse 将 text 解析为模板的主体，并关联定义的命名模板（{{define …}} 或 {{block …}} 语句），这些模板与 t 关联，并从 t 自身的定义中移除。

Templates can be redefined in successive calls to Parse. A template definition with a body containing only white space and comments is considered empty and will not replace an existing template’s body. This allows using Parse to add new named template definitions without overwriting the main template body.

可以在连续的 Parse 调用中重新定义模板。如果模板定义的主体只包含空白和注释，则被视为空，并且不会替换现有模板的主体。这允许使用 Parse 添加新的命名模板定义，而不覆盖主模板的主体。

(*Template) ParseFS <- go1.16

1

func (t *Template) ParseFS(fsys fs.FS, patterns ...string) (*Template, error)

ParseFS is like ParseFiles or ParseGlob but reads from the file system fsys instead of the host operating system’s file system. It accepts a list of glob patterns. (Note that most file names serve as glob patterns matching only themselves.)

ParseFS 类似于 ParseFiles 或 ParseGlob，但从文件系统 fsys 而不是主机操作系统的文件系统中读取。它接受一系列的通配符模式。（注意，大多数文件名本身作为只匹配自身的通配符模式。）

(*Template) ParseFiles

1

func (t *Template) ParseFiles(filenames ...string) (*Template, error)

ParseFiles parses the named files and associates the resulting templates with t. If an error occurs, parsing stops and the returned template is nil; otherwise it is t. There must be at least one file. Since the templates created by ParseFiles are named by the base names of the argument files, t should usually have the name of one of the (base) names of the files. If it does not, depending on t’s contents before calling ParseFiles, t.Execute may fail. In that case use t.ExecuteTemplate to execute a valid template.

ParseFiles 解析指定的文件，并将生成的模板与 t 关联。如果发生错误，解析会停止，并且返回的模板为 nil；否则为 t。至少要有一个文件。由于 ParseFiles 创建的模板以参数文件的基本名称命名，因此 t 通常应该具有其中一个（基本）文件名的名称。如果没有，则根据调用 ParseFiles 前 t 的内容，t.Execute 可能会失败。在这种情况下，请使用 t.ExecuteTemplate 来执行有效的模板。

When parsing multiple files with the same name in different directories, the last one mentioned will be the one that results.

当在不同目录中解析具有相同名称的多个文件时，最后一个被提及的文件将成为结果。

(*Template) ParseGlob

1

func (t *Template) ParseGlob(pattern string) (*Template, error)

ParseGlob parses the template definitions in the files identified by the pattern and associates the resulting templates with t. The files are matched according to the semantics of filepath.Match, and the pattern must match at least one file. ParseGlob is equivalent to calling t.ParseFiles with the list of files matched by the pattern.

ParseGlob 解析与模式匹配的文件中的模板定义，并将生成的模板与 t 关联。文件的匹配遵循 filepath.Match 的语义，模式必须匹配至少一个文件。ParseGlob 等效于使用模式匹配的文件列表调用 t.ParseFiles。

When parsing multiple files with the same name in different directories, the last one mentioned will be the one that results.

当在不同目录中解析具有相同名称的多个文件时，最后一个被提及的文件将成为结果。

(*Template) Templates

1

func (t *Template) Templates() []*Template

Templates returns a slice of defined templates associated with t.

Templates 返回与 t 关联的已定义模板的切片。