PowerShell:函数没有正确的返回值 [英] PowerShell: Function doesn't have proper return value
问题描述
我写了一个powershell脚本来比较两个文件夹的内容:
$ Dir1 =d:\ TEMP \\ Dir1
$ Dir2 =d:\ TEMP \Dir2
函数测试差异($ Dir1,$ Dir2){
$ fileList1 = Get-ChildItem $ Dir1 -Recurse | Where-Object {!$ _。PsIsContainer} | Get-Item | Sort-Object -Property Name
$ fileList2 = Get-ChildItem $ Dir2 -Recurse | Where-Object {!$ _。PsIsContainer} | Get-Item | ($ fileList1.Count -ne $ fileList2.Count){
Write-Host以下文件不同:
比较对象 - 属性名称
如果ReferenceObject $ fileList1 -DifferenceObject $ fileList2 - 属性名称-PassThru |格式表FullName
返回$ false
}
返回$ true
}
$ i =测试比较$ Dir1 $ Dir2
如果($ i){
写输出Test OK
} else {
写主机测试失败-BackgroundColor Red
}
如果我在 Compare-Object
,然后我在控制台中运行这个命令,我得到了不同的列表。如果我运行整个脚本,我不会得到任何输出。为什么?
我正在使用PowerGUI脚本编辑器,但我也尝试了普通的ps控制台。
编辑:
问题是检查脚本的结尾。
<$ p $如果($ i){
写输出Test OK
...
= $ $ $ $ $ $ = Test-Diff $ Dir1 $ Dir2
...
如果我调用 Test-Diff
code> $ i = 检查,它的工作原理!
$ b
Test-Diff
返回一个对象数组,而不是预期的bool值:
[DBG]:PS D:\>> $ i | ForEach-Object {$ _。GetType()} |格式 - 表 - 属性名称
名称
----
FormatStartData
GroupStartData
FormatEntryData
GroupEndData
FormatEndData
布尔
如果我用比较对象
注释掉了这一行,那么返回值就是一个布尔值,正如预期的那样。
<问题是:为什么?
我在这里找到了答案: http://martinzugec.blogspot.hu/2008/08/returning-values-from-fuctions-
功能栏{
[System.Collections.ArrayList] $ MyVariable = @()
$ MyVariable.Add(a)
$ MyVariable.Add(b)
返回$ MyVariable
}
使用PowerShell方法返回对象:@(0,1 ,a,b)而不是@(a,b)
要使该函数按预期工作,您需要重定向输出为空:
功能栏{
[System.Collections.ArrayList] $ MyVariable = @()
$ MyVariable.Add(a)| Out-Null
$ MyVariable.Add(b)| Out-Null
返回$ MyVariable
}
在我们的例子中,函数必须按照Koliat的建议重构。
I wrote a powershell script to compare the content of two folders:
$Dir1 ="d:\TEMP\Dir1"
$Dir2 ="d:\TEMP\Dir2"
function Test-Diff($Dir1, $Dir2) {
$fileList1 = Get-ChildItem $Dir1 -Recurse | Where-Object {!$_.PsIsContainer} | Get-Item | Sort-Object -Property Name
$fileList2 = Get-ChildItem $Dir2 -Recurse | Where-Object {!$_.PsIsContainer} | Get-Item | Sort-Object -Property Name
if($fileList1.Count -ne $fileList2.Count) {
Write-Host "Following files are different:"
Compare-Object -ReferenceObject $fileList1 -DifferenceObject $fileList2 -Property Name -PassThru | Format-Table FullName
return $false
}
return $true
}
$i = Test-Diff $Dir1 $Dir2
if($i) {
Write-Output "Test OK"
} else {
Write-Host "Test FAILED" -BackgroundColor Red
}
If I set a break point on Compare-Object
, and I run this command in console, I get the list of differences. If I run the whole script, I don't get any output. Why?
I'm working in PowerGUI Script Editor, but I tried the normal ps console too.
EDIT:
The problem is the check on the end of the script.
$i = Test-Diff $Dir1 $Dir2
if($i) {
Write-Output "Test OK"
...
If I call Test-Diff
without $i =
check, it works!
Test-Diff
returns with an array of objects and not with an expected bool value:
[DBG]: PS D:\>> $i | ForEach-Object { $_.GetType() } | Format-Table -Property Name
Name
----
FormatStartData
GroupStartData
FormatEntryData
GroupEndData
FormatEndData
Boolean
If I comment out the line with Compare-Object
, the return value is a boolean value, as expected.
The question is: why?
I've found the answer here: http://martinzugec.blogspot.hu/2008/08/returning-values-from-fuctions-in.html
Functions like this:
Function bar {
[System.Collections.ArrayList]$MyVariable = @()
$MyVariable.Add("a")
$MyVariable.Add("b")
Return $MyVariable
}
uses a PowerShell way of returning objects: @(0,1,"a","b") and not @("a","b")
To make this function work as expected, you will need to redirect output to null:
Function bar {
[System.Collections.ArrayList]$MyVariable = @()
$MyVariable.Add("a") | Out-Null
$MyVariable.Add("b") | Out-Null
Return $MyVariable
}
In our case, the function has to be refactored as suggested by Koliat.
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