Splitting Functions from Scripts in bulk

Time to read: 2.5 minutes

Words: 504

Previously on…

I’ve talked before about a couple of topics that this blog post pertains to

That is the relevant information so you’re up to speed on where I am.

Bring on the stupid

The stupid thing that I was doing was that I was manually, visually scanning the script, copying out the function definitions, and pasting them into their own function files.

This was long, this was tedious, and this was not a efficient use of my time.

Especially since the scripts were not laid out as logically as I would have liked.

Personally if I were to have nested functions in a script, I would have them towards the beginning of the file. Together, maybe in a little region that I’ve called “functions”.

Actually, if I have to have a “functions” region, then I have too many functions and I’m going to split them out anyway.

The scripts I was looking at were not laid out this way.

Sure there were what appeared to be a function region but there were also functions further down the script, created just before they were needed.

Hence, manually scanning the whole script, taking a note and a copy of each function before moving on again.

Long, tedious, wasteful.

There is a way!

Like I mentioned at the start, in the “pertinent” region, Chris Dent has a function that we have availed of before that we can use her.

Let’s take a look at what it gives us…

First of all, we get a list of the build scripts.

Get-ChildItem -Path .\Git\build-scripts\ -Filter *.ps1

So we now have a list of the scripts. Each one of these scripts may, or may not, have one or many functions defined within them.

How are we going to get these?

We pipe this list to our Get-FunctionInfo function.

Get-ChildItem -Path .\Git\build-scripts\ -Filter *.ps1 |
    Get-FunctionInfo -ErrorAction SilentlyContinue -IncludeNested

Perfect! Now to automate the final part of manual process. Can we grab the definition of these functions and split them out to a separate file per function?

First question is can we grab the function definitions?

Get-ChildItem -Path .\Git\build-scripts\ -Filter *.ps1 |
    Get-FunctionInfo -ErrorAction SilentlyContinue -IncludeNested |
 ForEach-Object {
    $_.Scriptblock.Ast.Parent.Extent.Text 
 }
I’m going to ignore that GetCurrentDateFormat function

Final bit

Now that we know that we can grab the function definition, it’s a quick step to out the contents into a file.

Get-ChildItem -Path .\Git\build-scripts\ -Filter *.ps1 |
    Get-FunctionInfo -ErrorAction SilentlyContinue -IncludeNested |
 ForEach-Object {
    $_.Scriptblock.Ast.Parent.Extent.Text |
        Out-File -FilePath ".\Git\build-scripts\build\$($_.Name).ps1"
 }

And just to double check…

Lovely!

All the functions are split off into their own .ps1 file where they can be reviewed, tests can be created for them, and/or improved.

It’s nice to push the bottleneck down the pipeline. Now I’m wondering if there’s a way we can bulk introduce Pester tests…