Add -FormatEnumerationLimit parameter to Format-List and Format-Table

Summary of the new feature / enhancement

With PowerShell, you sometimes get objects which have properties that are actually an array of objects. The Threads and Modules Properties on System.Diagnostics.Process object. When Format-List/Format-Table formats these parameters, they only include up to a certain number of occurrences, by default 4. The number of enumerations shown is determined by the automatic variable $FormatEnumerationLimit. So if you want more, you just update that variable, typically in a $Profile.

Here is the current behaviour:

PS> $FormatEnumerationLimit
4
PS> Get-Process | Select-Object -Property Name, Threads -First 4

Name                    Threads
----                    -------
AggregatorHost          {5240}
ApplicationFrameHost    {16968, 2848, 18728}
AppVShNotify            {9164}
Atom.SDK.WindowsService {4064, 4908, 4912, 19144…}

PS> $FormatEnumerationLimit = 1
PS> Get-Process | Select-Object -Property Name, Threads -First 4

Name                    Threads
----                    -------
AggregatorHost          {5240}
ApplicationFrameHost    {16968…}
AppVShNotify            {9164}
Atom.SDK.WindowsService {4064…}

I propose adding a new parameter to both Format-List and Format-Table, -FormatEnumerationLimit which overrdes the value of $FormatEnumerationLimit, but just for this command. Like this:

PS> Get-Process | Select-Object -First 4 | Format-Table Name, Threads -FormatEnumerationLimit 2

Name                    Threads
----                    -------
AggregatorHost          {5240}
ApplicationFrameHost    {16968, 2848…}
AppVShNotify            {9164}
Atom.SDK.WindowsService {4064, 4908…}

Proposed technical implementation details (optional)

• Update each cmdlet with the extra parameter
• Change the logic for handling enumeration limit by using the parameter value if it is specified.
• Retain the default value and default variable handling.

[rkeithhill]

Given that this proposal is limited to the Format-List|Table commands, Format in the parameter name seems redundant. You could shorten the parameter name to -EnumerationLimit.

[jhoneill]

That’s a very weak argument against the improvement.

Our only policy is to keep backward compatibility. And even this is already unbelievable It has limits. Any new switch for an existing cmdlet breaks things. Old scripts run on new PWSH (with relatively few exceptions) but I’ve used things from PS 5 and found the customer’s servers hadn’t been upgraded from 4, I’m writing today in 7.2 and testing in 5 because it’s Windows PowerShell only on these machines, so I can’t use convertFrom-Secure string or the new operators etc. etc. “Don’t use X if you want the script to work down-level” is OK advice. It’s certainly better than "You can’t have X because then you can’t run the script somewhere that you wouldn’t want to 😃