How PSCustomObject Really Works

In a previous tip we explained how PSCustomObject can create new objects really fast:

$o = [PSCustomObject]@{
    Date     = Get-Date
    BIOS     = Get-WmiObject -Class Win32_BIOS
    Computer = $env:COMPUTERNAME
    OS       = [Environment]::OSVersion
    Remark   = 'Some remark'
}

In reality, [PSCustomObject] is not a type, and you are not casting a hash table, either. What truly happens behind the scenes is the combination of two steps that you can also execute separately:

#requires -Version 3.0

# create an ordered hash table
$hash = [Ordered]@{
    Date     = Get-Date
    BIOS     = Get-WmiObject -Class Win32_BIOS
    Computer = $env:COMPUTERNAME
    OS       = [Environment]::OSVersion
    Remark   = 'Some remark'
}

# turn hash table in object
$o = New-Object -TypeName PSObject -Property $hash

Since the code uses ordered hash tables which were introduced in PowerShell 3.0, you cannot use either approach in PowerShell 2.0. To support PowerShell 2.0: use a non-ordered (conventional) hash table instead:

#requires -Version 2.0

# create a hash table
$hash = @{
    Date     = Get-Date
    BIOS     = Get-WmiObject -Class Win32_BIOS
    Computer = $env:COMPUTERNAME
    OS       = [Environment]::OSVersion
    Remark   = 'Some remark'
}

# turn hash table in object
$o = New-Object -TypeName PSObject -Property $hash

$o

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