Shell 将可选参数传递给子例程而不实例化它们

我有一个脚本，提示用户输入（网址、用户名和密码等），并验证这些输入或再次提示用户

现在，我希望能够调用这个脚本，同时在命令行上提供其中一些参数，方法是将它们作为可选参数，并将它们传递给原始子例程。但是，在脚本的范围内，我可以测试参数是否随

$PSBoundParameters.ContainsKey（'a'）

一起提供，但一旦我将参数

$a

（可能未提供）传递给函数，相同的测试将始终返回

$True

示例代码：

function main {
    param (
        [string]$a
    )
    if ($PSBoundParameters.ContainsKey('a')) {
        "main - a is $a"
    }
    else {
        "main - didn't get a"
    }
    getStr $a
}

function getStr {
    param (
        [string]$a
    )
    if ($PSBoundParameters.ContainsKey('a')) {
        "getStr - a is $a"
    }
    else {
        "getStr - didn't get a"
    }
}

main

main "hello"

main - didn't get a
getStr - didn't get a

main - a is hello
getStr - a is hello

main - didn't get a
getStr - a is

main - a is hello
getStr - a is hello

输入：

function main {
    param (
        [string]$a
    )
    if ($PSBoundParameters.ContainsKey('a')) {
        "main - a is $a"
    }
    else {
        "main - didn't get a"
    }
    getStr $a
}

function getStr {
    param (
        [string]$a
    )
    if ($PSBoundParameters.ContainsKey('a')) {
        "getStr - a is $a"
    }
    else {
        "getStr - didn't get a"
    }
}

main

main "hello"

main - didn't get a
getStr - didn't get a

main - a is hello
getStr - a is hello

main - didn't get a
getStr - a is

main - a is hello
getStr - a is hello

预期输出：

function main {
    param (
        [string]$a
    )
    if ($PSBoundParameters.ContainsKey('a')) {
        "main - a is $a"
    }
    else {
        "main - didn't get a"
    }
    getStr $a
}

function getStr {
    param (
        [string]$a
    )
    if ($PSBoundParameters.ContainsKey('a')) {
        "getStr - a is $a"
    }
    else {
        "getStr - didn't get a"
    }
}

main

main "hello"

main - didn't get a
getStr - didn't get a

main - a is hello
getStr - a is hello

main - didn't get a
getStr - a is

main - a is hello
getStr - a is hello

实际输出：

function main {
    param (
        [string]$a
    )
    if ($PSBoundParameters.ContainsKey('a')) {
        "main - a is $a"
    }
    else {
        "main - didn't get a"
    }
    getStr $a
}

function getStr {
    param (
        [string]$a
    )
    if ($PSBoundParameters.ContainsKey('a')) {
        "getStr - a is $a"
    }
    else {
        "getStr - didn't get a"
    }
}

main

main "hello"

main - didn't get a
getStr - didn't get a

main - a is hello
getStr - a is hello

main - didn't get a
getStr - a is

main - a is hello
getStr - a is hello

---

我猜想，

$a

是在调用

getStr$a

时实例化的，有没有更优雅/正确的方法来处理这个问题？

使用

@PSBoundParameters

。我修改了你的函数，所以我可以把它作为脚本运行

代码

param (
    [string]$a
)

function main {
    param (
        [string]$a
    )
    if ($PSBoundParameters.ContainsKey('a')) {
        "main - a is $a"
    }
    else {
        "main - didn't get a"
    }
    getStr @PSBoundParameters
}

function getStr {
    param (
        [string]$a
    )
    if ($PSBoundParameters.ContainsKey('a')) {
        "getStr - a is $a"
    }
    else {
        "getStr - didn't get a"
    }
}
main @PSBoundParameters

输出

PS C:\> .\code.ps1 -a string
main - a is string
getStr - a is string
PS C:\> .\code.ps1
main - didn't get a
getStr - didn't get a

---

谢谢，这就解决了前面提到的问题。如果可以的话-如果我可能会得到几个参数，每个子例程只需要检查一个参数呢？为了将来的参考-我自己测试了这个，我只需将飞溅的（

@

）

PSBoundVariables

发送到每个函数，它会检查它想要的键。