Best way to add results to an array across multiple functions in PowerShell?

Question

I want to perform a series of checks on some infrastructure, and if the check fails, add it to a list. At the end of the workflow, write the results list. Pseudo code:

Function CheckSomething
{
    # Perform a check here. If check failed, add to the results list.
}

Function CheckSomethingElse
{
    # Perform another check. If check failed, add to the results list.
}

Function ShowResults
{
    $results;
}

CheckSomething;
CheckSomethingElse;
ShowResults;

I would like to avoid using global variables. How would you solve it? Use a collections.arraylist?

Update

I tried the following suggestion from @mjolinor

Function CheckSomething
{
   # Perform a check here. If check failed, add to the results list
   $check = $true
   if ($check -eq $true) {$results[CheckSomething] = 'Pass'}
   else {$results[CheckSomething] = 'Fail}'
}

Function CheckSomethingElse
{
    # Perform another check. If check failed, add to the results list.
    $check = $false
    if ($check -eq $true) {$results[CheckSomethingElse] = 'Pass'}
    else {$results[CheckSomethingElse] = 'Fail}'

}

Function ShowResults
{
    $results;
}

$results = @{}
CheckSomething
CheckSomethingElse
ShowResults

And I get:

Missing or invalid array index expression.
At C:\Users\moomin\Documents\errorsTest.ps1:5 char:36
+    if ($check -eq $true) {$results[ <<<< CheckSomething] = 'Pass'}
    + CategoryInfo          : ParserError: ([:String) [], ParseException
    + FullyQualifiedErrorId : MissingArrayIndexExpression

This is a follow-on question from here.

What type of variable you use has no bearing on the use of a global/non-global variable. Some people would say that there is nothing wrong with a global variable or singleton object. A lot of times they would be right. Personally I tend to avoid them because I feel it makes my code more portable. The way to avoid one in your case is to return the failed list as an array and add it to an array that is technically in the global scope but not being directly accessed in the individual functions. — EBGreen
– EBGreen, Commented Dec 11, 2013 at 16:05

Peter Mortensen · Accepted Answer · 2019-02-22 19:58:23Z

1

Another option is to use a hash table:

Function CheckSomething
{
   # Perform a check here. If check failed, add to the results list.
   if ($check -eq $true) {$results['CheckSomething'] = 'Pass'}
   else {$results['CheckSomething'] = 'Fail}'
}

Function CheckSomethingElse
{
    # Perform another check. If check failed, add to the results list.
    if ($check -eq $true) {$results['CheckSomethingElse'] = 'Pass'}
    else {$results['CheckSomethingElse'] = 'Fail}'
}

Function ShowResults
{
    $results;
}

$Results = @{}
CheckSomething
CheckSomethingElse
ShowResults

edited Feb 22, 2019 at 19:58

Peter Mortensen

31.4k22 gold badges110 silver badges134 bronze badges

answered Dec 11, 2013 at 15:50

mjolinor

68.7k7 gold badges118 silver badges141 bronze badges

Sign up to request clarification or add additional context in comments.

8 Comments

EBGreen Over a year ago

This is still using a global variable which the OP wanted to avoid.

mjolinor Over a year ago

It is using a variable in a parent scope, but that is not the same thing as using an explicitly global variable.

mjolinor Over a year ago

That's my fault. The name of the hash table key needs to be quoted. I've updated the posted script.

EBGreen Over a year ago

@mjolinor you are correct that it is not declared as a global. It still couples the functions just as much as a global though.

mjolinor Over a year ago

In this application, where there is a separate function to display the results some kind of coupling seems unavoidable.

|

beavel · Accepted Answer · 2013-12-11 17:22:47Z

0

Referencing your initial post, I believe the simplest way would be to take your original approach and use the $Script: scope:

Function CheckSomething
{
    # perform a check here, if check failed add to the results list
    $Script:results += 'Added Content'
}

Function CheckSomethingElse
{
    # perform another check,  if check failed add to the results list
    $Script:results += 'Added Content'
}

Function ShowResults
{
    $results;
}

$results = @();
CheckSomething;
CheckSomethingElse;
ShowResults;

Since you are defining $results at the script level already, you just need to make sure that inside your functions you are referencing that variable at the appropriate scope by append $Script:.

edited Dec 11, 2013 at 17:22

answered Dec 11, 2013 at 17:15

beavel

1,0871 gold badge8 silver badges16 bronze badges

Collectives™ on Stack Overflow

Best way to add results to an array across multiple functions in PowerShell?

2 Answers 2

8 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

8 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related