使用扩展字符串作为 Powershell 函数参数 [英] Using expanding strings as Powershell function parameters

问题描述

我正在尝试编写一个函数，该函数将打印针对用户提供的姓名的用户提供的问候语.我想在此代码块中以我可以使用的方式使用扩展字符串:

I'm trying to write a function that will print a user-supplied greeting addressed to a user-supplied name. I want to use expanding strings the way I can in this code block:

$Name = "World"  
$Greeting = "Hello, $Name!"
$Greeting

成功打印Hello, World!.但是，当我尝试将这些字符串作为参数传递给这样的函数时，

Which successfully prints Hello, World!. However, when I try to pass these strings as parameters to a function like so,

function HelloWorld
{  
    Param ($Greeting, $Name)
    $Greeting
}
HelloWorld("Hello, $Name!", "World")

我得到输出

Hello, !  
World  

经调查，Powershell 似乎完全忽略了 "Hello, $Name!" 中的 $Name，运行

Upon investigation, Powershell seems to be ignoring $Name in "Hello, $Name!" completely, as running

HelloWorld("Hello, !", "World")

产生与上面相同的输出.此外，它似乎没有将 "World" 视为 $Name 的值，因为运行

Produces output identical to above. Additionally, it doesn't seem to regard "World" as the value of $Name, since running

function HelloWorld
{  
    Param ($Greeting, $Name)
    $Name
}
HelloWorld("Hello, $Name!", "World")

不产生任何输出.

当作为函数参数传入时，有没有办法让扩展字符串起作用?

Is there a way to get the expanding string to work when passed in as a function parameter?

推荐答案

出现您的问题是因为 $Name 字符串替换发生在函数外部，在 $Name 变量填充在函数内部.

Your issue occurs because the $Name string replacement is happening outside of the function, before the $Name variable is populated inside of the function.

你可以这样做:

function HelloWorld
{  
    Param ($Greeting, $Name)
    $Greeting -replace '\$Name',$Name
}

HelloWorld -Greeting 'Hello, $Name!' -Name 'World'

通过使用单引号，我们发送 Hello, $Name 的字面问候，然后在函数内部使用 -Replace 替换这个字符串(我们有将 \ 放在我们要替换的字符串中的 $ 之前，因为 $ 是正则表达式特殊字符).

By using single quotes, we send the literal greeting of Hello, $Name in and then do the replacement of this string inside the function using -Replace (we have to put a \ before the $ in the string we're replace because $ is a regex special character).

这篇关于使用扩展字符串作为 Powershell 函数参数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！