[PowerShell每日技巧]确保代码的向后兼容性(20140212)

DAIC

Let's assume you have created this function:

1. function Test-Function
   
2. {
   
3.   param
   
4.   (
   
5.     [Parameter(Mandatory=$true)]
   
6.     $ServerPath
   
7.   )
   
8. 
   
9.   "You selected $ServerPath"
   
10. }

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It works fine, but half a year later in a code review, your boss wants you to use standard parameter names, and rename "ServerPath" to "ComputerName". So you change your function appropriately:

1. function Test-Function
   
2. {
   
3.   param
   
4.   (
   
5.     [Parameter(Mandatory=$true)]
   
6.     $ComputerName
   
7.   )
   
8. 
   
9.   "You selected $ComputerName"
   
10. }

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What you cannot easily control, though, is who else calls your function, and may still use the old parameter. So to ensure backward compatibility, make sure your function can still work with the old parameter name, too:

1. function Test-Function
   
2. {
   
3.   param
   
4.   (
   
5.     [Parameter(Mandatory=$true)]
   
6.     [Alias("ServerPath")]
   
7.     $ComputerName
   
8.   )
   
9. 
   
10.   "You selected $ComputerName"
    
11. }

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Old code can now still run, and new code (and code completion) will use the new name:

PS> Test-Function -ComputerName server1 You selected server1 PS> Test-Function -ServerPath server1 You selected server1

http://powershell.com/cs/blogs/tips/archive/2014/02/12/ensuring-backward-compatibility.aspx

DAIC

如果需要定义两个参数的别名：

1. [Alias("ServerPath","CN")]

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