Adding methods with ScriptMethod in PowerShell - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this PowerShell script adding a ScriptMethod?

Consider this PowerShell code that adds a ScriptMethod to a custom object. What will be the output when calling the method?

PowerShell

$obj = New-Object PSObject -Property @{Name='Alice'}
$scriptBlock = { "Hello, $($this.Name)!" }
$obj | Add-Member -MemberType ScriptMethod -Name Greet -Value $scriptBlock
$obj.Greet()

A Hello, Alice!

B Hello, $this.Name!

C Hello, Name!

D Error: Method not found

💡 Hint

Remember that $this inside a ScriptMethod refers to the object itself.

The ScriptMethod uses $this to access the object's properties. Since Name is 'Alice', the method returns 'Hello, Alice!'.

📝 Syntax

intermediate

Which option correctly adds a ScriptMethod to a PowerShell object?

You want to add a ScriptMethod named 'SayBye' to a PSObject that returns 'Goodbye, !'. Which code snippet is correct?

A $obj | Add-Member -MemberType ScriptMethod -Name SayBye -Value { "Goodbye, this.Name!" }

B $obj | Add-Member -MemberType ScriptMethod -Name SayBye -Value { "Goodbye, $Name!" }

C $obj | Add-Member -MemberType ScriptMethod -Name SayBye -Value { "Goodbye, $this->Name!" }

D $obj | Add-Member -MemberType ScriptMethod -Name SayBye -Value { "Goodbye, $($this.Name)!" }

💡 Hint

Inside ScriptMethod, use $this to refer to the object itself.

Option D correctly uses $this.Name inside the script block to access the object's Name property. Other options use invalid syntax or miss the $this reference.

🔧 Debug

advanced

Why does this ScriptMethod fail to access the object's property?

Given this code, why does calling $obj.Hello() produce an error? $obj = New-Object PSObject -Property @{Name='Bob'} $sb = { "Hi, $Name!" } $obj | Add-Member -MemberType ScriptMethod -Name Hello -Value $sb $obj.Hello()

A Because $Name is not defined inside the script block; should use $this.Name

B Because Add-Member requires -PassThru to work with ScriptMethod

C Because PSObject cannot have ScriptMethods added

D Because the script block must be a string, not a script block

💡 Hint

Think about how to access object properties inside ScriptMethod script blocks.

Inside a ScriptMethod, $this refers to the object. $Name alone is undefined, causing an error. Using $this.Name fixes the issue.

🚀 Application

advanced

How to add a ScriptMethod that modifies an object property?

You want to add a ScriptMethod 'SetAge' to a PSObject that sets its 'Age' property to a given value. Which code correctly does this?

A $obj | Add-Member -MemberType ScriptMethod -Name SetAge -Value { $Age = $args[0] }

B $obj | Add-Member -MemberType ScriptMethod -Name SetAge -Value { param($a) $this.Age = $a }

C $obj | Add-Member -MemberType ScriptMethod -Name SetAge -Value { param($a) $Age = $a }

D $obj | Add-Member -MemberType ScriptMethod -Name SetAge -Value { param($a) this.Age = $a }

💡 Hint

Use $this to refer to the object and param() to accept arguments.

Option B correctly defines a parameter and assigns it to $this.Age. Other options either miss $this or have invalid syntax.

🧠 Conceptual

expert

What happens if you add multiple ScriptMethods with the same name to a PSObject?

If you add two ScriptMethods named 'Action' to the same PSObject, what will be the result when calling $obj.Action()?

A Both methods run sequentially when calling $obj.Action()

B The last added ScriptMethod overwrites the previous one; calling $obj.Action() runs the last method

C PowerShell throws an error when adding a duplicate ScriptMethod

D Calling $obj.Action() runs the first added method, ignoring the second

💡 Hint

Add-Member throws an error when adding a member with a name that already exists unless -Force is specified.

PowerShell throws an error when trying to add a duplicate ScriptMethod unless the -Force parameter is used. By default, Add-Member does not overwrite existing members.