Powershell: Make ValueFromPipelineByPropertyName default to $true

[Quaentor]

Enhancement

Make parameter ValueFromPipelineByPropertyName default to $true.

Though, I'm not sure it won't cause hardship in some cases.
At least it seems rational and compelling.

[jhoneill]

It does seem rational and compelling to begin with.

However. Because you don't know what objects might be piped into a command you don't know what might use a command parameter name as a property name. This would cause some objects to fail while others worked, and command the failure might be very subtle. e.g. I pipe objects which have "Start" or "end" as a property into a command and the values for "Start and End" parameters are now set which they weren't before.

[vexx32]

Yep. Typically there are only a few parameters which can be meaningfully used in a pipeline context when handling input.

There's a lot more to making a parameter work with the pipeline than _just_ the attribute. You have to code the function or cmdlet in a way that actually works with the pipeline, being sure to use the value in the process{} / ProcessRecord() areas and not the begin / end areas, where pipeline parameter values are not guaranteed to be defined.

It's opt-in because you have to specifically code the function or cmdlet to operate correctly and expect the values to be set at specific points; you can't just add the attribute and expect it to work automatically. As a result, making it opt-out and not opt-in would most likely just break quite a few commands rather than improving things. 🙂