Using Appropriate DataTypes (Part 2)

In part 1 we looked at how data becomes more accessible when converted to a more appropriate .NET data type.

If you can’t find an existing data type for your data to provide it with structure, you can create your own data types as well.

Let’s assume you need to handle names. Here’s a custom data type called [TeamMember] that can add structure to names:

class TeamMember
{
    [string]$FirstName
    [string]$LastName


    TeamMember([string]$Name)
    {
        # case correct text
        $newName = [cultureinfo]::InvariantCulture.TextInfo.ToTitleCase($Name) 
        # automatically find delimiter character
        $delimiter = $newName.ToCharArray() -match '[,. ]' | Select-Object -First 1

        # no delimiter?
        if ($delimiter.Count -eq 0)
        {
            $this.LastName = $Name
            return
        }

        $array = $newName.Split($delimiter)
                
        # based on found delimiter
        switch -Regex ($delimiter)
        {
            # dot or space:
            '[.\s]'   { 
                        $this.FirstName = $array[0]  
                        $this.LastName = $array[1]
                     }
            # comma
            '\,'     { 
                        $this.FirstName = $array[1]  
                        $this.LastName = $array[0]
                     }
            # invalid
            default  { 
                        $this.LastName = $Name
                     }
        }
    }
}

Once you run this code, you defined a new datatype called [TeamMember]. Now it’s simple to convert a string containing a name to a structured data type:

 
PS> [TeamMember]'tobias weltner'

FirstName LastName
--------- --------
Tobias    Weltner 



PS> [TeamMember]'tobias.weltner'

FirstName LastName
--------- --------
Tobias    Weltner 



PS> [TeamMember]'weltner,tobias'

FirstName LastName
--------- --------
Tobias    Weltner   
 

As an added benefit, you get automatic case correction, or in general: your class can incorporate any wizardry you like. When you later use the type, you no longer need to worry about it.

Even better, when you assign this type to a variable, it will auto convert any name to the new structure even in future assignments:

 
PS> [TeamMember]$name = 'Tobias Weltner'

PS> $name

FirstName LastName
--------- --------
Tobias    Weltner 


PS> $name = 'kloVER,kaRL'

PS> $name

FirstName LastName
--------- --------
Karl      Klover   
 

The secret of auto conversion for custom classes is its constructor. When the constructor accepts one argument of type [string], it then can automatically convert any string into the new structure.

The constructor of the class is always named like the class and is indeed accepting [string]:

TeamMember([string]$Name)
    { 
        ...
    }

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