CODEWITHSUNDEEP
powershell
newbie programmer
newbie programmer

Reputation: 97

How can I create a constructor?

In my last question, Stack Overflow helped me fix an error with my methods, so now I have a class like

class Main
{
    [int]$A
    [string]$B
    [bool]$C
}

class myClass : Main
{
    myClass(){
        $This.A = 1
        $This.B = "Property"
        $This.C = $False
    }

    [void] AM([string]$Argument) {
        Write-Host $Argument
        $This.C = $True
    }
}

Which has the method AM, but how can I make constructors like

[myClass]::myConstructor()

Upvotes: 0

Views: 48

Answers (1)

Nico Nekoru
Nico Nekoru

Reputation: 3112

PowerShell syntax is generally similar to C# syntax since they both use the .NET framework. It seems like you are confusing static operators and constructors.

Constructors are basically the inputs the class could take. For example:

class Main
{
    [int]$A
    [string]$B
    [bool]$C
}

class myClass : Main
{
    myClass(){
        $This.A = 1
        $This.B = "Property"
        $This.C = $False
    }

    [void] AM([string]$Argument) {
        Write-Host $Argument
        $This.C = $True
    }
}

In your class,

    myClass(){
        $This.A = 1
        $This.B = "Property"
        $This.C = $False
    }

Is the constructor. They contain the properties from the ::new() static operator (This may have caused your confusing).

A static operator is like a method but with static operators (::). You define static operators with Static [void] or a different type depending on the output type you want. Example:

    Static [void] AS() {
        Write-Host "Test"
    }

In a class like

class Main
{
    [int]$A
    [string]$B
    [bool]$C
}

class myClass : Main
{
    myClass(){
        $This.A = 1
        $This.B = "Property"
        $This.C = $False
    }

    [void] AM([string]$Argument) {
        Write-Host $Argument
        $This.C = $True
    }

    Static [void] AC() {
        Write-Host "Test"
    }
}

You can call the static operator with

[myClass]::AS()

with the output

Test

Which you can't do with methods:

PS C:\> [myClass]::AM("Argument")
Method invocation failed because [myClass] does not contain a method named 'AM'.
At line:1 char:1
+ [myClass]::AM()
+ ~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : MethodNotFound

Technically static operators are treated as methods but they are different.

Of course you can also have arguments in your static operator as well, they are basically methods just called differently:

class Main
{
    [int]$A
    [string]$B
    [bool]$C
}

class myClass : Main
{
    myClass(){
        $This.A = 1
        $This.B = "Property"
        $This.C = $False
    }

    Static [void] AC([string]$Argument) {
        Write-Host $Argument
    }
}

and

PS C:\> [myClass]::AC("Test")
Test
PS C:\> [myClass]::AC("Argument")
Argument

Upvotes: 2

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