Tab completion for command parameters shows invalid candidates

[oising]

I can't see immediately why this happens, but here's a repro:

# this works, in that -dingtone is not shown as a candidate
set-psreadlineoption -dingtone foo -ding<tab>

# this does not work, in that it shows the parameter repeatedly as a choice
set-psreadlineoption -addtohistoryhandler foo -addtohistory<tab>

A cursory look at parameter metadata yield no clues, sorry!

[oising]

Oh, I see that the latter - failing case - has an [AllowNullAttribute] - could that be it?

[lzybkr]

This is a general PowerShell issue.

As odd as it sounds, it looks like it depends whether or not there are multiple parameters with a common prefix. If there is a common prefix for more than 1 parameter, PowerShell will never suggest an already specified parameter.

If the parameter has a unique prefix, PowerShell will suggest that parameter even if it has been specified.

Try this:

function foo($qqq, $zzz1, $zzz2) {}
foo -qqq 1 -q<TAB>            # will suggest -qqq
foo -zzz1 1 -z<TAB>           # will only suggest -zzz2
foo -zzz1 1 -zzz2 2 -z<TAB>   # will suggest neither -zzz1 nor -zzz2

[oising]

But it's a bug, right? I think you might know the guy who wrote the tab completion stuff, no? :)

[lzybkr]

I asked the author of that code (no, it wasn't me) and he said it was by design, but I convinced him it was a bad design so he now considers it a bug. Maybe open a bug on Connect?

[oising]

Ok, I'll just log it as it stands - I thought you were trying to justify
the behaviour as by-design too. I just presumed I was too sober to
understand and planned on drinking a few glasses of wine and reading your
mail again.

-Oisin

On Wed, May 15, 2013 at 2:10 PM, Jason Shirk [email protected]:

I asked the author of that code (no, it wasn't me) and he said it was by
design, but I convinced him it was a bad design so he now considers it a
bug. Maybe open a bug on Connect?

—
Reply to this email directly or view it on GitHubhttps://github.com//issues/1#issuecomment-17955905
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