PowerShell script modularization June 10, 2008
Posted by reddogaw in PowerShell.Tags: dot-sourcing, modularization, PowerShell, Script re-use
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PowerShell has been a sneaky beast whose power is just now starting to creep into my programming psyche. Being the good OO citizen that I am I immediately started wanting to modularize my PowerShell scripts and functions for maximum re-use and easy organisation.
There are a number of ways to modularize your PowerShell including (but probably not limited to!):
- (Not recommended) Breaking down script blocks into functions and organising code consistently within the single .ps1 script file
- Organising functions into multiple individual .ps1 script files and dot-sourcing them
- TIP: Make use of Get-ScriptDirectory function to form relative paths from your current script location
- For most effective use, it’s recommended to keep only functions defined in your dot-sourced scripts and call them individually.
- Organising repeatable script blocks into multiple individual .ps1 script files that are parameterised and call them using the Call operator (& ) [See Kirk's link why dot-sourcing should be avoided]
- Note: I’m not talking about using functions, rather a normal .ps1 script with inline calls
- See Kirk’s great post on invoking or calling scripts within scripts
- Remember, anything used with the return keyword is what is assignable when using call operators (. and & )
- Anything that is output to host can be piped into certain host/stream redirection cmdlets (e.g. Out-File, Out-Null, Out-String)
- Defining functions in your user or system profile (Profile.ps1)
- Remember, this could be a deployment and backup problem
- Writing .NET compiled cmdlets
- Compiled functions written in .NET languages and deployed in specially attributed assemblies and then specifically registered into PowerShell
Love,
Reddog.
Getting the current script directory in PowerShell June 4, 2008
Posted by reddogaw in PowerShell, Tips.Tags: $pwd, Get-ScriptDirectory, PowerShell, Powershell Profile, Script Directory
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One thing to remember when developing PowerShell scripts is that your current value in $PWD is the process’ current directory not the one where the script was stored.
In my desire to break out a few functions into a common file in order to load them “dot-sourced” (so that the functions become global) I realised I needed help!
In comes a new function from the PowerShell Team Blog. It’s going straight into my PowerShell Profile: Get-ScriptDirectory. It does exactly as the name says, it gets the current directory that script is executed from.
<snip>
- function Get-ScriptDirectory
- {
- $Invocation = (Get-Variable MyInvocation -Scope 1).Value
- Split-Path $Invocation.MyCommand.Path
- }
</snip>
So that now from my script that requires the Common-Functions.ps1 (located in the same directory) I can call:
- # Load up our common functions
- $commons = Join-Path (Get-ScriptDirectory) “Common-Functions.ps1″;
- . $commons;
Love,
Reddog.
