Powershell 陷阱 [英] Powershell pitfalls

问题描述

您陷入了哪些 Powershell 陷阱?:-)

What Powershell pitfalls you have fall into? :-)

我的是:

# -----------------------------------
function foo()
{
    @("text")
}

# Expected 1, actually 4.
(foo).length

# -----------------------------------
if(@($null, $null))
{
    Write-Host "Expected to be here, and I am here."
}

if(@($null))
{
    Write-Host "Expected to be here, BUT NEVER EVER."
}

# -----------------------------------

function foo($a)
{
    # I thought this is right.
    #if($a -eq $null)
    #{
    #    throw "You can't pass $null as argument."
    #}

    # But actually it should be:
    if($null -eq $a)
    {
        throw "You can't pass $null as argument."
    }
}

foo @($null, $null)

# -----------------------------------

# There is try/catch, but no callstack reported.
function foo() 
{
   bar
}

function bar() 
{
  throw "test"
}

# Expected:
#  At bar() line:XX
#  At foo() line:XX
#  
# Actually some like this:
#  At bar() line:XX
foo

想知道你的，带他们四处走走:-)

Would like to know yours to walk them around :-)

推荐答案

我个人最喜欢的是

function foo() {
  param ( $param1, $param2 = $(throw "Need a second parameter"))
  ...
}

foo (1,2)

对于那些不熟悉 powershell 的人，该行会抛出该行，因为它实际上创建了一个数组并传递了一个参数，而不是传递 2 个参数.你必须按如下方式调用它

For those unfamiliar with powershell that line throws because instead of passing 2 parameters it actually creates an array and passes one parameter. You have to call it as follows

foo 1 2

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