CODEWITHSUNDEEP
powershell
Will I Am
Will I Am

Reputation: 2682

Passing only provided parameters

Given two functions f1, f2, how can f2 call to f2 with only the parameters that have a value?

Suppose:

function f1($p1, $p2, $p3)
{
    f2 -p1 $p1 -p2  $p2 -p3 $p3 # how do i write this line correctly?

}

function f2($p1=100, $p2=200, $p3=300)
{
    write-host "P1: $p1"
    write-host "P2: $p2"
    write-host "P3: $p3"
}

Correct:

calling:  f2 -p1 1 -p3 3
returns: P1: 1, P2: 200, P3: 3

Incorrect:

calling: f1 -p1 1 -p3 3
returns: P1: 1, P2: , P3: 3
but i want: P1: 1, P2: 200, P3: 3

What I want to happen is that if I didn't provide a P2 value when calling f1(), when it gets to f2(), it should get the default value for P2, so P2 should be "200".

I can accomplish this by testing each parameter and if it is defined, and add it to a collection so i can use splatting, but can I simplify this and not have to test each parameter?

Upvotes: 2

Views: 68

Answers (2)

AdminOfThings
AdminOfThings

Reputation: 25041

I do not know if the other answers were clear enough to achieve the exact results. I am taking some ideas from Axel Anderson's Answer.

function f1($p1, $p2, $p3)
{
    f2 @PSBoundParameters

}

function f2($p1=100, $p2=200, $p3=300)
{
    write-host "P1: $p1"
    write-host "P2: $p2"
    write-host "P3: $p3"
}

Output:

f1 -p1 1 -p3 3
P1: 1
P2: 200
P3: 3

f1 -p1 1 -p3 3 -p2 2
P1: 1
P2: 2
P3: 3

Keep in mind that this only works because your parameter names are identical in both functions.

Upvotes: 2

Axel Andersen
Axel Andersen

Reputation: 1128

Try this:

function f1
{
    param ($p1,$p2,$p3)
    $PSBoundParameters.Keys | foreach {'{0}: {1}' -f $_,$PSBoundParameters[$_]}
}

calling: f1 -p1 1 -p3 3
p1: 1
p2: 3

Upvotes: 4

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