Avoiding avoidable errors in PowerShell

Avoiding avoidable errors in PowerShell

Two wonderful features of PowerShell that don't seem to get used enough are embodied by the cmdlet Set-PSDebug

##Tracing some of the things

PS C:\>Set-PSDebug -Trace 1

Trace level 1 gives you an idea of the execution of a script, like which path is taken after a conditional is evaluated.

##Tracing all the things

Even better is level 2 which shows everything level 1 does plus variable assignments (! SET ) and function calls (! CALL).

PS C:\>Set-PSDebug -Trace 2

##Strict all the things

The other nice feature of Set-PSDebug is the strict option:

PS C:\>Set-PSDebug -Strict

Strict will raise an error if you accidentally mistype the name of a variable thereby creating a new, uninitialised one with a slightly different name. This setting applies globally across all functions that you run.
One gotcha to watch out for, if you mistype the name in an expanded string it won't be flagged by strict.

##Strict some of the things

A more nuanced version of strict is the Set-StrictMode cmdlet which is scope aware and can be applied to single functions rather than the global reach of Set-PSDebug. StrictMode comes in two flavours, version 1 works in the same way as the Set-PSDebug -Strict
switch and suffers from the same gotcha in expanded strings.

PS C:\>Set-StrictMode -Version 1

As you might have guessed, StrictMode also has a version 2 setting.

PS C:\>Set-StrictMode -Version 2

Version 2 does catch uninitialized variables in expanded strings as well as in normal code. It also looks for functions being called as methods, unnamed variables, mistyped object properties.

##Strict none of the things

Turn off strict mode again using:

PS C:\>Set-PSDebug -Off


PS C:\>Set-StrictMode -Off