Perl 中的“我的"和“我们的"有什么区别? [英] What is the difference between 'my' and 'our' in Perl?
问题描述
我知道 Perl 中的 my 是什么.它定义了一个仅存在于定义它的块范围内的变量.我们的有什么作用?
I know what my is in Perl. It defines a variable that exists only in the scope of the block in which it is defined. What does our do?
our 与 my 有何不同?
推荐答案
our 与 <有何不同code>my 以及 our 有什么作用?
How does our differ from my and what does our do?
总结:
自 Perl 5 起可用，my 是一种声明非包变量的方法，即:
Available since Perl 5, my is a way to declare non-package variables, that are:
- 私人
- 新
- 非全局
- 与任何包分开，这样变量不能以
$package_name::variable的形式被访问.
- private
- new
- non-global
- separate from any package, so that the variable cannot be accessed in the form of
$package_name::variable.
另一方面，我们的变量是包变量，因此自动:
On the other hand, our variables are package variables, and thus automatically:
- 全局变量
- 绝对不是私人的
- 不一定是新的
- 可以在包(或词法范围)之外使用限定的命名空间，如
$package_name::variable.
- global variables
- definitely not private
- not necessarily new
- can be accessed outside the package (or lexical scope) with the
qualified namespace, as
$package_name::variable.
使用 our 声明变量允许您预先声明变量以便在 use strict 下使用它们code> 不会出现错字警告或编译时错误.从 Perl 5.6 开始，它已经取代了过时的 use vars，后者只是文件范围的，而不是词法范围的 我们的.
Declaring a variable with our allows you to predeclare variables in order to use them under use strict without getting typo warnings or compile-time errors. Since Perl 5.6, it has replaced the obsolete use vars, which was only file-scoped, and not lexically scoped as is our.
例如，package main 中变量 $x 的正式限定名称是 $main::x.声明 our $x 允许您使用裸 $x 变量而不会受到惩罚(即，不会导致错误)，在声明的范围内，当脚本使用use strict 或use strict "vars".范围可能是一个、两个或多个包，或者一个小块.
For example, the formal, qualified name for variable $x inside package main is $main::x. Declaring our $x allows you to use the bare $x variable without penalty (i.e., without a resulting error), in the scope of the declaration, when the script uses use strict or use strict "vars". The scope might be one, or two, or more packages, or one small block.
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