PowerShell - 在特定范围内执行脚本块 [英] PowerShell - execute script block in specific scope

问题描述

我正在尝试在 Powershell 中实现 RSpec/Jasmine 之类的 BDD 框架(或者至少研究制作一个的潜在问题).

I am trying to implement RSpec/Jasmine like BDD framework in Powershell (or at least research the potential problems with making one).

目前我在实现简单的前/后功能时遇到问题.给定

Currently I am having problems with implementing simple before/after functionality. Given

$ErrorActionPreference = "Stop"

function describe()
    {
    $aaaa = 0;
    before { $aaaa = 2; };
    after { $aaaa; }
    }

function before( [scriptblock]$sb )
    {
    & $sb
    }

function after( $sb )
    {
    & $sb
    }

describe

输出是 0，但我希望它是 2.有没有办法在 Powershell 中实现它(除了使 $aaaa 全局化，在脚本块中遍历父作用域直到找到 $aaaa，使 $aaaa 成为对象"和其他肮脏的黑客:) )

the output is 0, but I would like it to be 2. Is there any way to achieve it in Powershell (short of making $aaaa global, traversing parent scopes in script blocks till $aaaa is found, making $aaaa an "object" and other dirty hacks:) )

我最想要的是一种在其他范围内调用脚本块的方法，但我根本不知道这是否可行.我在 https 上发现了一个有趣的例子://connect.microsoft.com/PowerShell/feedback/details/560504/scriptblock-gets-incorrect-parent-scope-in​​-module(请参阅解决方法)，但不确定它是如何工作的以及是否有帮助我以任何方式.

What I would ideally like is a way to invoke a script block in some other scope but I don't have a clue whether it is possible at all. I found an interesting example at https://connect.microsoft.com/PowerShell/feedback/details/560504/scriptblock-gets-incorrect-parent-scope-in-module (see workaround), but am not sure how it works and if it helps me in any way.

TIA

推荐答案

调用运算符 (&) 始终使用新的作用域.相反，使用点源 (.) 运算符:

The call operator (&) always uses a new scope. Instead, use the dot source (.) operator:

$ErrorActionPreference = "Stop"

function describe()
    {
    $aaaa = 0;
    . before { $aaaa = 2; };
    . after { $aaaa; }
    }

function before( [scriptblock]$sb )
    {
    . $sb
    }

function after( $sb )
    {
    . $sb
    }

describe

注意的使用.function 调用与定义`$aaaa 的作用域相同的函数.

Note the use of . function to invoke the function in same scope as where `$aaaa is defined.

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