Perl中my($ variableName)和my $ variableName之间的区别是什么？

Question

Perl my ($variableName) 和my $variableNamePerl有什么区别？括号怎么办？

Answer 1

重要的效果是在声明变量的同时初始化变量:

my ($a) = @b;   # assigns  $a = $b[0]
my $a = @b;     # assigns  $a = scalar @b (length of @b)

另一个重要的是当你声明多个变量时.

my ($a,$b,$c);  # correct, all variables are lexically scoped now
my $a,$b,$c;    # $a is now lexically scoped, but $b and $c are not

如果你,最后一句话会给你一个错误use strict.

Answer 2

有关运营商的更多信息,请查看perdoc perlsubmy.这是一个小摘录:

概要:

   my $foo;            # declare $foo lexically local
   my (@wid, %get);    # declare list of variables local
   my $foo = "flurp";  # declare $foo lexical, and init it
   my @oof = @bar;     # declare @oof lexical, and init it
   my $x : Foo = $y;   # similar, with an attribute applied

Answer 3

简短的回答是,当在左侧使用括号时强制列表上下文=.

每个其他答案都指出了一个具体的案例,这会产生影响.实际上,您应该通读perlfunc以更好地了解在列表上下文中调用时函数的行为方式与标量上下文相反.