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How to Use PowerShell Splatting? Best PowerShell 101

In this article, we will delve into the world of PowerShell splatting and explore how it can revolutionize your scripting experience. We will learn how to leverage splatting to enhance the readability of your code, simplify parameter management, and promote code reuse. Whether you’re a beginner or an experienced PowerShell user, mastering splatting will take your scripting skills to the next level.

Understanding PowerShell Splatting

PowerShell splatting is a technique that allows you to pass a collection of parameters to a cmdlet or function using a hashtable (@{}) or an array (@()), rather than specifying each parameter individually. Splatting provides a more organized and flexible way to handle multiple parameters, making your code easier to read, maintain, and reuse.

With splatting, you define a hashtable or an array that contains parameter names as keys and their corresponding values. This collection is then passed as an argument to a cmdlet or function using the @ symbol followed by the variable name.

Traditional Parameters vs Splatting

When working with PowerShell, you have different options for passing parameters to cmdlets or functions. Two common approaches are traditional parameters and splatting parameters. Let’s explore the differences between them.

Traditional Parameters: In the traditional approach, you pass parameters individually, specifying each parameter and its corresponding value when calling a cmdlet or function. For example:

Get-Process -Name "notepad" -FileVersionInfo
Traditional Parameters - How to Use PowerShell Splatting? Best PowerShell 101

This method is straightforward and easy to understand, especially for simple commands with a few parameters. However, as the number of parameters increases, the command can become lengthy and harder to read. It may also lead to repetitive code if you need to reuse the same parameters across multiple commands.

Splatting Parameters: Splatting is an alternative technique that offers a more organized and flexible way to pass parameters. Instead of specifying each parameter individually, you use a hashtable (@{}) or an array (@()) to define the parameters and their corresponding values. Then, you pass this collection as an argument using the @ symbol followed by the variable name. For example:

$parameters = @{
    Name = "notepad"
    FileVersionInfo = $true
}

Get-Process @parameters
Splatting Parameters

Using splatting parameters provides several advantages. It enhances code readability by consolidating multiple parameters into a single, well-structured variable. This makes your code more concise and easier to understand, especially when dealing with commands that require numerous parameters.

How to Override a Splatted Parameter?

When using splatting parameters in PowerShell, you may encounter situations where you need to override a specific parameter value from the splatting collection. While splatting is convenient for passing multiple parameters, it doesn’t prevent you from modifying individual parameter values when necessary.

To override a splatted parameter, you can simply assign a new value to it after splatting the parameters. Here’s an example:

$parameters = @{
    Name = "notepad"
    FileVersionInfo = $true
}

# Splatting the parameters
Get-Process @parameters

# Modifying the FileVersionInfo parameter
$parameters.FileVersionInfo = $false

Using the updated parameters
Get-Process @parameters
How to Override a Splatted Parameter?

In the code snippet above, we define a hashtable $parameters with two parameters: Name and FileVersionInfo. We then splat the parameters using @parameters in the Get-Process cmdlet.

To override the FileVersionInfo parameter, we simply update its value by assigning a new value to $parameters.FileVersionInfo. In this case, we change it from $true to $false.

Finally, we reuse the updated parameters by splatting them again in the Get-Process cmdlet. This time, the FileVersionInfo parameter will have the new value specified.

Positional Parameters & Splatting Arrays 

In PowerShell, you can use positional parameters to simplify command execution by providing an array of values that correspond to the parameters’ positions. This approach allows you to pass multiple values to a command without explicitly specifying each parameter. It becomes even more powerful when combined with splatting, which lets you use an array to provide values for multiple parameters simultaneously.

When splatting arrays, PowerShell automatically maps each value in the array to its corresponding positional parameter in the command. Here’s an example to illustrate this concept:

$parameters = "John", "Doe", "example@email.com"

Splatting the array of parameters
Set-User @parameters
Positional Parameters & Splatting Arrays 

In the code snippet above, we define an array $parameters that contains three values: “John”, “Doe”, and “example@email.com“. We then splat the array using @parameters in the Set-User command.

The values in the array are automatically mapped to the positional parameters of the Set-User command. The first value “John” is assigned to the first positional parameter, the second value “Doe” to the second positional parameter, and so on.

What is the Best Way to Learn PowerShell Basics?

When learning PowerShell basics, applying powerShell text replacement tips can greatly enhance your understanding. Utilize online tutorials and resources that provide step-by-step instructions. Practice by actively using the commands, variables, and scripts to gain hands-on experience. Participating in forums and engaging with the PowerShell community can also contribute to your learning journey.

Splatted Commands & Proxy Functions

A proxy function acts as an intermediary between the caller and the target command or function. It allows you to modify the behavior of the original command or function by intercepting the parameters and applying custom logic. When it comes to splatting, proxy functions enable you to use splatting with commands or functions that do not have built-in splatting capabilities.

Here’s an example to illustrate the concept of using proxy functions for splitting:

function Invoke-MyCommand {
    param (
        [Parameter(Mandatory)]
        [string]$Param1,

        [Parameter(Mandatory)]
        [string]$Param2
    )

    # Custom logic goes here
    # ...
}

function Invoke-MyCommandProxy {
    param (
        [Parameter(Mandatory)]
        [hashtable]$SplatParams
    )

    Invoke-MyCommand @SplatParams
}
Splatted Commands & Proxy Functions

In the code snippet above, we have the Invoke-MyCommand function, which requires two mandatory parameters, $Param1 and $Param2. However, it doesn’t support splatting directly. To enable splatting, we create a proxy function called Invoke-MyCommandProxy. The proxy function accepts a hashtable parameter, $SplatParams, which will contain the key-value pairs for the parameters we want to pass.

The $Args & $PSBoundParameters

The $Args variable contains an array that represents all the arguments passed to a function or script. It provides a convenient way to access and manipulate these arguments regardless of their number or order. You can access individual elements of the $Args array using indexing, such as $Args[0] for the first argument, $Args[1] for the second argument, and so on.

Here’s an example to demonstrate the usage of $Args:

function Process-Args {
    foreach ($arg in $Args) {
        Write-Host "Argument: $arg"
    }
}

Process-Args "Hello", "World", 123
The $Args & $PSBoundParameters

In the above code, the Process-Args function accepts any number of arguments and iterates over them using a foreach loop. Each argument is then printed to the console using Write-Host.

The $PSBoundParameters variable, on the other hand, provides a hashtable that contains the parameters explicitly bound to the current function or script. It includes both named parameters and their corresponding values. This variable is particularly useful when dealing with dynamic parameters or when you want to inspect and manipulate the parameter values programmatically.

Here’s an example illustrating the usage of $PSBoundParameters:

function Process-Params {
    foreach ($key in $PSBoundParameters.Keys) {
        $value = $PSBoundParameters[$key]
        Write-Host "Parameter: $key, Value: $value"
    }
}

Process-Params -Param1 "Hello" -Param2 "World"
The $Args & $PSBoundParameters

In the above code, the Process-Params function loops over the keys of $PSBoundParameters and retrieves the corresponding values. It then displays the parameter names and their values using Write-Host.

Wrapper Function with a Splatted Parameter

To create a wrapper function with a splatted parameter, you define the function with a parameter that uses the @ symbol before the parameter name to indicate that it will receive a hashtable of parameters. Inside the function, you can then use the splatting operator @ to pass the hashtable as individual parameters to the target command.

Here’s an example to illustrate how to create a wrapper function with a splatted parameter:

Wrapper Function with a Splatted Parameter

In the above code, the Get-Wrapper function is defined with a single parameter $Parameters of type Hashtable. This parameter is marked as mandatory to ensure that it is always provided when calling the wrapper function.

By using a wrapper function with a splatted parameter, you can create a convenient and flexible interface for executing commands with customized or modified parameters. This approach allows you to simplify complex commands, add additional logic or validation, and enhance the functionality of existing cmdlets or functions in your PowerShell scripts and modules. Happy Browsing!