1. Introduction  

Splatting is a feature in PowerShell that allows you to bundle a set of parameters into a single variable, typically a hashtable, and then pass that variable to a command using the "splat" operator (@). This technique not only reduces repetition but also enhances code readability and maintainability.

In this article, we will explore the concept of splatting in PowerShell and delve into its various benefits and use cases. We will also provide practical examples to demonstrate how splatting can significantly improve your PowerShell scripts.

2. Overview of Splatting  

Splatting offers several advantages when it comes to parameter passing in PowerShell. Let's take a look at some of its key benefits:

1. Code Simplicity: By using splatting, you can consolidate multiple parameters into a single variable. This simplifies the command invocation by reducing the number of parameter arguments and eliminates the need for repetitive parameter entries.

2. Readability and Maintainability: Splatting enhances code readability by providing a clear separation between the command and its associated parameters. It makes it easier to understand and modify the code, especially when dealing with complex command invocations that require multiple parameters.

3. Dynamic Parameter Addition: Splatting allows you to dynamically add or remove parameters based on conditions or logic. This flexibility enables you to adjust the set of parameters passed to a command at runtime, making your scripts more adaptable and versatile.

4. Reusability: Once you have defined a parameter set as a splatting variable, you can reuse it across multiple commands without duplicating the parameter values. This saves effort and promotes consistency in your script's parameter handling.

3. Example Scenario  

Let's consider a scenario where we have a PowerShell script that needs to authenticate remote connections and perform operations on a specific computer. The script involves two commands: Test-WSMan and Get-CimInstance. We will initially examine the code without using splatting to understand the repetitive nature of passing parameters individually.

# Parameters used to authenticate remote connections

$remoteParams = @{
    Credential = Get-Credential
    ComputerName = $env:COMPUTERNAME
}

# Parameters which are specific to Test-WSMan
$testWSMan = @{
    Authentication = 'Default'
    ErrorAction = 'SilentlyContinue'
}

# By default, do not pass any extra parameters to New-CimSession
$newCimSession = @{}

if (-not (Test-WSMan @testWSMan @remoteParams)) {
    # If WSMan fails, use DCOM (RPC over TCP) to connect
    $newCimSession['SessionOption'] = New-CimSessionOption -Protocol Dcom
}

# Parameters to pass to Get-CimInstance
$getCimInstance = @{
    ClassName = 'Win32_Service'
    CimSession = New-CimSession @newCimSession @remoteParams
}

Get-CimInstance @getCimInstance

Code Breakdown  

In the above example, we have three sets of parameters defined:

1. $remoteParams: These parameters are used to authenticate remote connections. We specify the Credential parameter, which prompts the user for credentials, and the ComputerName parameter, which is set to the value of the $env:COMPUTERNAME environment variable.

2. $testWSMan: These parameters are specific to the Test-WSMan command. We set the Authentication parameter to 'Default' and the ErrorAction parameter to 'SilentlyContinue'.

3. $newCimSession: This hashtable is used to store parameters for the New-CimSession command. By default, we initialize it as an empty hashtable.

The script first uses Test-WSMan to check if the WS-Management service is available on the specified remote computer. If the WSMan test fails, indicating that the remote computer doesn't support WS-Management, the script modifies the $newCimSession hashtable to use DCOM (RPC over TCP) for the connection.

Finally, the script invokes Get-CimInstance with parameters defined in the $getCimInstance hashtable. This command retrieves instances of the Win32_Service class using the New-CimSession command as the CimSession parameter.

Repetitive Nature of Passing Parameters Individually  

If we look closely at the code, we can observe that passing parameters individually can lead to redundancy. The same parameters, such as Credential and ComputerName, need to be repeated for each command, making the code longer and less maintainable. Additionally, if any changes are required for these parameters, they need to be updated at multiple places in the script, increasing the chances of errors and inconsistencies.

In the next section, we will introduce splatting as a solution to eliminate this repetition and simplify the code.

4. Splatting Solution  

Splatting is a powerful technique in PowerShell that allows us to bundle a set of parameters into a single variable and pass it to a command using the splatting operator (@). Let's see how splatting can address the repetition issue in our example code and improve its readability.

# Parameters used to authenticate remote connections

$remoteParams = @{
    Credential = Get-Credential
    ComputerName = $env:COMPUTERNAME
}

# Parameters which are specific to Test-WSMan
$testWSMan = @{
    Authentication = 'Default'
    ErrorAction = 'SilentlyContinue'
}

# By default, do not pass any extra parameters to New-CimSession
$newCimSession = @{}

if (-not (Test-WSMan @testWSMan @remoteParams)) {
    # If WSMan fails, use DCOM (RPC over TCP) to connect
    $newCimSession['SessionOption'] = New-CimSessionOption -Protocol Dcom
}

# Parameters to pass to Get-CimInstance
$getCimInstance = @{
    ClassName = 'Win32_Service'
    CimSession = New-CimSession @newCimSession @remoteParams
}

Get-CimInstance @getCimInstance

Code Breakdown with Splatting  

In the modified code, we continue using the three sets of parameters defined earlier. However, instead of passing the parameters individually, we create hashtables to hold the parameter sets. The splatting technique is employed when invoking the respective commands.

By utilizing splatting, we have achieved the following:

1. The $remoteParams hashtable contains the parameters for authenticating remote connections. The Credential and ComputerName parameters are defined just once and then passed using splatting wherever required.

2. Similarly, the $testWSMan hashtable holds the parameters specific to the Test-WSMan command. By using splatting, we pass these parameters to the command without repetition.

3. The $newCimSession hashtable remains the same, serving as the container for parameters related to the New-CimSession command. Again, splatting is employed to pass the parameters without redundancy.

4. The $getCimInstance hashtable is used to define the parameters for the Get-CimInstance command. We pass the parameters to the command using splatting, ensuring a concise and readable code structure.

By leveraging splatting, we have eliminated the repetition of parameters, resulting in a cleaner and more maintainable script. The code has become more concise, and any modifications or additions to the parameters can be made in a single location, improving efficiency and reducing the chances of errors.

5. Key Features of Splatting  

In the previous sections, we explored an example scenario where splatting was used to avoid repetition and improve the readability of the code. Let's now highlight some key features of using splatting in PowerShell scripts to avoid repetition.

Key Features of Splatting:

• Parameter Bundling: Splatting allows you to bundle multiple parameters into a single variable using hashtables. This simplifies the code by reducing the number of individual parameter entries.

• Splatting Operator: The splatting operator (@) expands the hashtable and passes the parameters to the command. It helps maintain a clean and concise syntax by avoiding the repetition of parameters.

• Dynamic Parameter Addition: Splatting provides the flexibility to dynamically add or remove parameters based on conditions or logic. This allows you to adjust the set of parameters passed to a command at runtime, making your scripts more adaptable to different scenarios.

• Improved Code Readability: By separating the command from its associated parameters, splatting enhances the readability of PowerShell scripts. It makes the code easier to understand and maintain, as the parameter sets can be defined once and reused across different command invocations.

6. Conclusion  

Splatting is a powerful technique in PowerShell that allows you to avoid repetition and improve the efficiency and readability of your scripts. By bundling parameters into hashtables and utilizing the splatting operator, you can significantly simplify your code and make it more concise. Splatting provides the advantage of parameter bundling, dynamic parameter addition, and improved code readability. By adopting splatting in your PowerShell scripting practices, you can enhance the efficiency and maintainability of your scripts, reduce redundancy, and make your code more adaptable to varying scenarios. Embrace splatting as a valuable tool in your PowerShell toolkit and unlock its potential to improve your script development experience.