再次导入同一个模块后，从模块导入的变量变为 $null [英] Variables imported from the module becomes $null, after the same module imported again

问题描述

我有一个简单的模块:varExp.psm1

I have a simple module: varExp.psm1

$var1 = 20

Export-ModuleMember -Variable var1

Export-ModuleMember -Variable var1

然后我将这个模块导入到 PS 会话中:

And I import this module into PS session:

PS>导入模块 .\varExp.psm1

PS> Import-Module .\varExp.psm1

然后

PS>$var1

20

但是在我第二次导入之后

But after I import it second time

PS>导入模块 .\varExp.psm1

PS> Import-Module .\varExp.psm1

PS>$var1

PS>

$var1 变为空...

$var1 becomes null...

有人知道这是怎么回事吗?(PS2.0)

Anybody knows what is going on here? (PS2.0)

有解决方法:使用 Import-Module .\varExp.psm1 -Force 强制重新加载，并测试之前是否加载了模块:if(-not (Get-Module varExp)) { 导入模块 .\varExp.psm1 }.但我希望在简单的情况下得到 $null 值背后的一些原因.

There are workarounds: Forcing reloading with Import-Module .\varExp.psm1 -Force, and testing if module was loaded before: if(-not (Get-Module varExp)) { Import-Module .\varExp.psm1 }. But I was hoping to get some reason behind $null value in simple case.

推荐答案

我不知道到底发生了什么，但是当你重新导入一个模块时，你必须使用 -Force.

I don't know exactly what happens, but when you are re-importing a module , you have to use -Force.

当您包含 -verbose 时，您可以看到两者之间的区别:

When you include -verbose you can see the difference between the two:

PS> import-module .\test -Verbose
VERBOSE: Importing variable 'var1'.

用力:

PS> import-module .\test -Verbose -Force
VERBOSE: Removing the imported "var1" variable.
VERBOSE: Loading module from path 'C:\test\test.psm1'.
VERBOSE: Importing variable 'var1'.

文档确实说明了以下内容:

The documentation does say the following:

如果您将具有相同名称和相同类型的成员导入到您的会话，Windows PowerShell 默认使用最后导入的成员.变量和别名被替换了，原来没有可访问.

If you import members with the same name and the same type into your session, Windows PowerShell uses the member imported last by default. Variables and aliases are replaced, and the originals are not accessible.

我认为原件不可访问意味着当你重新导入模块时，这个$var1是不可访问的.

I think the originals are not accessible means in this $var1 is not accessible when you re-import the module.

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