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PowerShell - Lazy Loading

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Lazy Loading

Code Properties

  • Language: PowerShell
  • Concepts: Deferred Loading, Proxy Functions

Overview

Lazy loading in PowerShell allows you to defer loading of resources, scripts, or modules until they are actually needed, optimizing performance and memory usage.

Common use cases:

  • Lazy loading modules
  • Lazy loading shell completion scripts
  • Lazy loading custom PowerShell profile components

Code

Lazy Loading Modules

function Get-ModuleCommand {
    <#
    .SYNOPSIS
    Use a script-scoped variable to track if the module is loaded
    #>
    if (-not $script:MyModuleLoaded) {
        Import-Module -Name MyModule
        $script:MyModuleLoaded = $true
    }
 
    # now call a command from the module
    MyModuleCommand
}

Dynamic Script Block Execution

# define a script block for lazy loading
$LazyCommand = {
    if (-not $script:MyModuleLoaded) {
        Import-Module -Name MyModule
        $script:MyModuleLoaded = $true
    }
    MyModuleCommand
}
 
# call the script block when needed
& $LazyCommand

Conditional Module Loading

function Get-LazyLoadedCommand {
    if (-not (Get-Module -Name MyModule -ListAvailable)) {
        Import-Module -Name MyModule
    }
 
    MyModuleCommand
}

Proxy Functions

function Invoke-MyLazyCommand {
    if (-not $script:MyModuleLoaded) {
        Import-Module -Name MyModule
        $script:MyModuleLoaded = $true
    }
 
    # replace this proxy function with the actual module command
    Set-Alias -Name Invoke-MyLazyCommand -Value Invoke-MyModuleCommand -Scope Script
    Invoke-MyLazyCommand
}

Usage

Choose the pattern that best fits your use case:

  • Script-scoped variable: Best for modules used multiple times in a session
  • Script blocks: Good for one-off commands that may or may not be needed
  • Proxy functions: Ideal for replacing commands after first use

Appendix

Note created on 2024-10-06 and last modified on 2024-12-31.

See Also

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