I was trying a few esoteric methods for collecting information, and noticed
an oddity when I was trying to find properties of repeated String[]
objects: Get-Member would repeat identical members over and over, under a
single System.String typename. Example below. Anyone know the reason for
this? My hunch is it is probably a bug and is probably due to repeated
hard-typed arrays:

PS> Get-ChildItem hklm:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall
| ForEach-Object { Get-Member -InputObject $_.GetValueNames() } |
Select-Object -First 200


TypeName: System.String[]

Name MemberType Definition
---- ---------- ----------
Count AliasProperty Count = Length
Address Method System.String& Address(Int32 )
....
Rank Property System.Int32 Rank {get;}
SyncRoot Property System.Object SyncRoot {get;}
Count AliasProperty Count = Length
Address Method System.String& Address(Int32 )
....
Rank Property System.Int32 Rank {get;}
SyncRoot Property System.Object SyncRoot {get;}
Count AliasProperty Count = Length
Address Method System.String& Address(Int32 )
....
Rank Property System.Int32 Rank {get;}
SyncRoot Property System.Object SyncRoot {get;}
Count AliasProperty Count = Length
Address Method System.String& Address(Int32 )
....

I'm not 100% sure, but I think this is what's going on:

Get-Member usually gives you member information only once for every type you
pipe into it (or hand over to it using -InputObject).
What you are doing is actually calling Get-Member several times
(Foreach-Object) and with one single object each time. So every time
Get-Member is invoked it returns type information for one single object
(String[]).
After that the all generated
"Microsoft.PowerShell.Commands.MemberDefinition"-objects get automagically
piped into PoSh's magic formating cmdlets, which recognize that all have
actually the same type and thus present the header
"Name MemberType Definition" only once for all members.

I hope that makes sense for you.
Please someone correct my if I'm wrong.

--
greetings
dreeschkind


"Alex K. Angelopoulos [MVP]" wrote:

> I was trying a few esoteric methods for collecting information, and noticed
> an oddity when I was trying to find properties of repeated String[]
> objects: Get-Member would repeat identical members over and over, under a
> single System.String typename. Example below. Anyone know the reason for
> this? My hunch is it is probably a bug and is probably due to repeated
> hard-typed arrays:
>
> PS> Get-ChildItem hklm:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall
> | ForEach-Object { Get-Member -InputObject $_.GetValueNames() } |
> Select-Object -First 200
>
>
> TypeName: System.String[]
>
> Name MemberType Definition
> ---- ---------- ----------
> Count AliasProperty Count = Length
> Address Method System.String& Address(Int32 )
> ....
> Rank Property System.Int32 Rank {get;}
> SyncRoot Property System.Object SyncRoot {get;}
> Count AliasProperty Count = Length
> Address Method System.String& Address(Int32 )
> ....
> Rank Property System.Int32 Rank {get;}
> SyncRoot Property System.Object SyncRoot {get;}
> Count AliasProperty Count = Length
> Address Method System.String& Address(Int32 )
> ....
> Rank Property System.Int32 Rank {get;}
> SyncRoot Property System.Object SyncRoot {get;}
> Count AliasProperty Count = Length
> Address Method System.String& Address(Int32 )
> ....
>
>
>

This is an example on how to avoid this phenomenon:

Get-ChildItem hklm:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall |
Select-Object -First 200 | ForEach-Object {$_.GetValueNames()} | Get-Member

--
greetings
dreeschkind


"dreeschkind" wrote:

> I'm not 100% sure, but I think this is what's going on:
>
> Get-Member usually gives you member information only once for every type you
> pipe into it (or hand over to it using -InputObject).
> What you are doing is actually calling Get-Member several times
> (Foreach-Object) and with one single object each time. So every time
> Get-Member is invoked it returns type information for one single object
> (String[]).
> After that the all generated
> "Microsoft.PowerShell.Commands.MemberDefinition"-objects get automagically
> piped into PoSh's magic formating cmdlets, which recognize that all have
> actually the same type and thus present the header
> "Name MemberType Definition" only once for all members.
>
> I hope that makes sense for you.
> Please someone correct my if I'm wrong.
>
> --
> greetings
> dreeschkind
>
>
> "Alex K. Angelopoulos [MVP]" wrote:
>
> > I was trying a few esoteric methods for collecting information, and noticed
> > an oddity when I was trying to find properties of repeated String[]
> > objects: Get-Member would repeat identical members over and over, under a
> > single System.String typename. Example below. Anyone know the reason for
> > this? My hunch is it is probably a bug and is probably due to repeated
> > hard-typed arrays:
> >
> > PS> Get-ChildItem hklm:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall
> > | ForEach-Object { Get-Member -InputObject $_.GetValueNames() } |
> > Select-Object -First 200
> >
> >
> > TypeName: System.String[]
> >
> > Name MemberType Definition
> > ---- ---------- ----------
> > Count AliasProperty Count = Length
> > Address Method System.String& Address(Int32 )
> > ....
> > Rank Property System.Int32 Rank {get;}
> > SyncRoot Property System.Object SyncRoot {get;}
> > Count AliasProperty Count = Length
> > Address Method System.String& Address(Int32 )
> > ....
> > Rank Property System.Int32 Rank {get;}
> > SyncRoot Property System.Object SyncRoot {get;}
> > Count AliasProperty Count = Length
> > Address Method System.String& Address(Int32 )
> > ....
> > Rank Property System.Int32 Rank {get;}
> > SyncRoot Property System.Object SyncRoot {get;}
> > Count AliasProperty Count = Length
> > Address Method System.String& Address(Int32 )
> > ....
> >
> >
> >

BTW, my example did not return members of String[] as you might have intended
to see, so here is a simplified version of your example that does this:

#members of [String[]]
[String]$a = "foo"
[String[]]$b = $a,$a
$b | % {gm -i $b}

This would be a more simplified example on the 'bug' your were seeing:

#members of [String]
"foo","bar" | % {$_ | gm}


--
greetings
dreeschkind

"dreeschkind" wrote:

> I'm not 100% sure, but I think this is what's going on:
>
> Get-Member usually gives you member information only once for every type you
> pipe into it (or hand over to it using -InputObject).
> What you are doing is actually calling Get-Member several times
> (Foreach-Object) and with one single object each time. So every time
> Get-Member is invoked it returns type information for one single object
> (String[]).
> After that the all generated
> "Microsoft.PowerShell.Commands.MemberDefinition"-objects get automagically
> piped into PoSh's magic formating cmdlets, which recognize that all have
> actually the same type and thus present the header
> "Name MemberType Definition" only once for all members.
>
> I hope that makes sense for you.
> Please someone correct my if I'm wrong.
>
> --
> greetings
> dreeschkind
>
>
> "Alex K. Angelopoulos [MVP]" wrote:
>
> > I was trying a few esoteric methods for collecting information, and noticed
> > an oddity when I was trying to find properties of repeated String[]
> > objects: Get-Member would repeat identical members over and over, under a
> > single System.String typename. Example below. Anyone know the reason for
> > this? My hunch is it is probably a bug and is probably due to repeated
> > hard-typed arrays:
> >
> > PS> Get-ChildItem hklm:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall
> > | ForEach-Object { Get-Member -InputObject $_.GetValueNames() } |
> > Select-Object -First 200
> >
> >
> > TypeName: System.String[]
> >
> > Name MemberType Definition
> > ---- ---------- ----------
> > Count AliasProperty Count = Length
> > Address Method System.String& Address(Int32 )
> > ....
> > Rank Property System.Int32 Rank {get;}
> > SyncRoot Property System.Object SyncRoot {get;}
> > Count AliasProperty Count = Length
> > Address Method System.String& Address(Int32 )
> > ....
> > Rank Property System.Int32 Rank {get;}
> > SyncRoot Property System.Object SyncRoot {get;}
> > Count AliasProperty Count = Length
> > Address Method System.String& Address(Int32 )
> > ....
> > Rank Property System.Int32 Rank {get;}
> > SyncRoot Property System.Object SyncRoot {get;}
> > Count AliasProperty Count = Length
> > Address Method System.String& Address(Int32 )
> > ....
> >
> >
> >