如何在 Perl 中访问函数参数？

发布于 2024-11-02 04:44:14 字数 473 浏览 4 评论 0原文

在 C++ 中我会这样做：

void some_func(const char *str, ...);
some_func("hi %s u r %d", "n00b", 420);

在 PHP 中我会这样做：

function some_func()
{
    $args = func_get_args();
}
some_func($holy, $moly, $guacomole);

How do I do that in Perl?

sub wut {
    # What goes here?
}

原文

In C++ I would do something like this:

void some_func(const char *str, ...);
some_func("hi %s u r %d", "n00b", 420);

In PHP I would do like this:

function some_func()
{
    $args = func_get_args();
}
some_func($holy, $moly, $guacomole);

How do I do that in Perl?

sub wut {
    # What goes here?
}

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一片旧的回忆 2024-11-09 04:44:14

您会这样做：

sub wut {
  my @args = @_;
  ...
}

当您调用函数时，Perl 会自动填充特殊的 @_ 变量。您可以通过多种方式访问它：

直接使用 @_ 或其中的单个元素作为 $_[0]、$_[1]< /code>，等等，
通过将其分配给另一个数组，如上所示
通过将其分配给标量列表（或可能是散列，或另一个数组，或其组合）：
```
子吴特{
  我的（$arg1，$arg2，$arg3，@others）=@_；
  ...
}
```

请注意，在这种形式中，您需要将数组 @others 放在end，因为如果你把它放在前面，它会吞掉 @_ 的所有元素。换句话说，这不起作用：

sub wut {
  my ( $arg1, @others, $arg2 ) = @_;
  ...
}

您还可以使用 shift 从 @_ 中提取值：

sub wut {
  my $arg1 = shift;
  my $arg2 = shift;
  my @others = @_;
  ...
}

请注意，shift 将自动起作用如果您不为其提供参数，则在 @_ 上。

编辑：您还可以通过使用哈希或哈希引用来使用命名参数。例如，如果您像这样调用 wut()：

wut($arg1, { option1 => 'hello', option2 => 'goodbye' });

...您可以执行以下操作：

sub wut {
  my $arg1 = shift;
  my $opts = shift;
  my $option1 = $opts->{option1} || "default";
  my $option2 = $opts->{option2} || "default2";
  ...
}

这将是将命名参数引入到函数中的好方法，以便您可以稍后添加参数并您不必担心它们通过的顺序。

You would do:

sub wut {
  my @args = @_;
  ...
}

Perl automatically populates the special @_ variable when you call a function. You can access it in multiple ways:

directly, by simply using @_ or individual elements within it as $_[0], $_[1], and so on
by assigning it to another array, as shown above
by assigning it to a list of scalars (or possibly a hash, or another array, or combinations thereof):
```
sub wut {
  my ( $arg1, $arg2, $arg3, @others ) = @_;
  ...
}
```

Note that in this form you need to put the array @others at the end, because if you put it in earlier, it'll slurp up all of the elements of @_. In other words, this won't work:

sub wut {
  my ( $arg1, @others, $arg2 ) = @_;
  ...
}

You can also use shift to pull values off of @_:

sub wut {
  my $arg1 = shift;
  my $arg2 = shift;
  my @others = @_;
  ...
}

Note that shift will automatically work on @_ if you don't supply it with an argument.

Edit: You can also use named arguments by using a hash or a hash reference. For example, if you called wut() like:

wut($arg1, { option1 => 'hello', option2 => 'goodbye' });

...you could then do something like:

sub wut {
  my $arg1 = shift;
  my $opts = shift;
  my $option1 = $opts->{option1} || "default";
  my $option2 = $opts->{option2} || "default2";
  ...
}

This would be a good way to introduce named parameters into your functions, so that you can add parameters later and you don't have to worry about the order in which they're passed.

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