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AvoidDynamicallyCreatingVariableNames.md

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description Avoid dynamic variable names, instead use a hash table or similar dictionary type.
ms.date 04/21/2026
ms.topic reference
title AvoidDynamicallyCreatingVariableNames

AvoidDynamicallyCreatingVariableNames

Severity Level: Information

Description

Don't create variables with dynamic names. It also makes the code difficult to understand and can lead to unexpected behavior if the variable names are not unique or if they collide with existing variables. A dynamic name is a name constructed using string concatenation or interpolation. This rule checks for the use of New-Variable with a dynamic name.

Note

This rule is not enabled by default. The user needs to enable it through settings.

How to Fix

Use a hash table or similar dictionary type to store values with dynamic keys. When you require a specific scope, option, or visibility, put the dictionary (hashtable) in that scope and apply the appropriate option or visibility.

Example

Wrong

'One', 'Two', 'Three' | ForEach-Object -Begin { $i = 1 } -Process {
    New-Variable -Name "My$_" -Value ($i++)
}
$MyTwo # returns 2

Correct

$My = @{}
'One', 'Two', 'Three' | ForEach-Object -Begin { $i = 1 } -Process {
    $My[$_] = $i++
}
$My.Two # returns 2

In this example, you want the values to be read-only and available in the script scope. Put the hashtable in the script scope and make it read-only.

New-Variable -Name My -Value @{} -Option ReadOnly -Scope Script
'One', 'Two', 'Three' | ForEach-Object -Begin { $i = 1 } -Process {
    $Script:My[$_] = $i++
}
$Script:My.Two # returns 2

Configuration

Rules = @{
    PSAvoidDynamicallyCreatingVariableNames = @{
        Enable = $true
    }
}

Parameters

  • Enable: bool (Default value is $false)

    Enable or disable the rule during ScriptAnalyzer invocation.

References

  • New-Variable