Why do I need to have my functions written first in my PowerShell script?

Question

I have a script that I am utilizing functions to wrap parts of the code that allow me to move through the sections at a specified point. What I have found is that I have to have the functions listed first in the script for it to run correctly.

Non-working example

$stepChoice = read-host 'Where would you like to start.'  switch($stepChoice) {     1{Step1}     2{Step2}     3{Step3}  }  # Steps.ps1  function Step1 {      'Step 1'      Step2  }  function Step2 {      'Step 2'      Step3  }  function Step3 {      'Step 3'      'Done!'  } 

Error

This give me the following error:

The term 'Step1' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.

 At C:\Tools\Scripts\functiontest.ps1:7 char:12   +     1{Step1 <<<< }   + CategoryInfo          : ObjectNotFound: (Step1:String) [], CommandNotFoundException   + FullyQualifiedErrorId : CommandNotFoundException* 

Working example

If I change the order around it works fine:

# Steps.ps1  function Step1 {      'Step 1'      Step2  }  function Step2 {      'Step 2'      Step3  }  function Step3 {      'Step 3'      'Done!'  }  #steps $stepChoice = read-host 'Where would you like to start.'  switch($stepChoice) {     1{Step1}     2{Step2}     3{Step3}  } 

Why?

I am guessing that it is because PS is not loading the functions.

Why is this and is there a better way to lay out this code structure?

Answer 1

Remember that in general, what works in a script should work at the command line.

This was not true in CMD. GOTO and FOR %I IN (...) DO %%I are two examples.

In PowerShell, I can run commands at the command line until I get the result I want, then paste the history in to a script, then edit out the extraneous bits.

Also, I can take a script that isn't working correctly, paste it in to an interactive shell, and study the resulting state.

At the interactive command line, there's no way you could write this:

 F function F { "Hello, World!" } 

However, when reading a script, I want to read the top-level code first, and then see more detail as I scroll down. One approach is:

 function Main  {     F }  function F {     "Hello, World!" }  Main