如何删除脚本块中的重复代码？

Question

Powershell 的新手。我正在编写一个脚本来监视目录中的文件并向控制台报告更改。

我注意到我用于 FS "watchers" 的脚本块中有相当多的代码重复。

这是脚本块的片段。如果需要，我可以 post 整个脚本，它有点长，还有更多内容。

# Filter all files
$filter = "*.*"
$watcher = New-Object IO.FileSystemWatcher $watchdir, $filter -Property @{
    IncludeSubdirectories = $true
    EnableRaisingEvents = $true
}

# File creation
Register-ObjectEvent $watcher Created -SourceIdentifier Created -Action {
    $path = $Event.SourceEventArgs.FullPath
    $name = $Event.SourceEventArgs.Name
    $changeType = $Event.SourceEventArgs.ChangeType
    $timeStamp = $Event.TimeGenerated
    $message = "The file '$name' was '$changeType' at '$timeStamp'"
    Write-Host $message
}

# File change
Register-ObjectEvent $watcher Changed -SourceIdentifier Changed -Action {
    $path = $Event.SourceEventArgs.FullPath
    $name = $Event.SourceEventArgs.Name
    $changeType = $Event.SourceEventArgs.ChangeType
    $timeStamp = $Event.TimeGenerated
    $message = "The file '$name' was '$changeType' at '$timeStamp'"
    Write-Host $message
}

# File rename
...

# File delete
...

是否有更好的模式或更好的写法来减少代码量？

Answer 1

您应该将重复使用的代码包装到函数中，有关如何操作的说明请参见此处：http://windowsitpro.com/windows/create-your-own-powershell-functions

对于您的情况，我将创建以下函数：

function FileChange {
  Register-ObjectEvent $watcher Created -SourceIdentifier Created -Action {
  $path = $Event.SourceEventArgs.FullPath
  $name = $Event.SourceEventArgs.Name
  $changeType = $Event.SourceEventArgs.ChangeType
  $timeStamp = $Event.TimeGenerated
  $console_message = "The file '$name' was '$changeType' at '$timeStamp'"
  Write-Host message
}

然后用它来替换重复的代码：

# Filter all files
$filter = "*.*"
$watcher = New-Object IO.FileSystemWatcher $watchdir, $filter -Property @{
IncludeSubdirectories = $true
EnableRaisingEvents = $true
}

# File creation
FileChange()

# File change
FileChange()

Answer 2

在您的示例中，脚本块完全相同，因此在这种情况下，只需将它们放入变量中并传递：

$action = {
    $path = $Event.SourceEventArgs.FullPath
    $name = $Event.SourceEventArgs.Name
    $changeType = $Event.SourceEventArgs.ChangeType
    $timeStamp = $Event.TimeGenerated
    $console_message = "The file '$name' was '$changeType' at '$timeStamp'"
    Write-Host message
}

# File creation
Register-ObjectEvent $watcher Created -SourceIdentifier Created -Action $action

# File change
Register-ObjectEvent $watcher Changed -SourceIdentifier Changed -Action $action

如果您 post 一个脚本块中存在冗余但它们并不完全相同的示例，那么展示一个如何最好地抽象它的示例会更容易。可能没有 one-size-fits-all 解决方案。

如何删除脚本块中的重复代码？

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