Singleton arrays treated as scalars

Singleton arrays treated as scalars

[Bart Schaefer]

I wrote:
} On Apr 15,  2:08pm, Sven Wischnowsky wrote:
} } Subject: Re: BUG: zsh-3.1.5-pws-14: parameter expansion not working proper
} }
} } Now, we could make the multsub() save (and at the end restore) the
} } value of, say `static int mult_isarr'. It then sets it to zero and
} } calls paramsubst() (via prefork(), as usual). At the end of
} } paramsubst() we set `mult_isarr = isarr'.
} 
} I actually tried this last night -- although I had paramsubst() set the
} static to 0 on the way in; multsub() just saved and restored it -- and
} it worked for some cases but not others, so I decided I was missing a
} subtlety somewhere and threw it out.

I tried this again and got much better results for two-or-more element
arrays, but singleton arrays were still getting subscripted as scalars.
Investigation led me to this fragment of paramsubst():

        if (isarr > 0 && !plan9 && (!aval || !aval[0])) {
            val = dupstring("");
            isarr = 0;
        } else if (isarr && aval && aval[0] && !aval[1]) {
            val = aval[0];
            isarr = 0;
        }

Well, look at that.  If we have a singleton array, make it into a scalar.
This doesn't have anything to do with multsub() at all!

Does anybody remember why this code is here?  What part of the world is
going to come crashing down if that "else if" clause gets deleted?

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com

Re: Singleton arrays treated as scalars

[Geoff Wing]

Bart Schaefer <schaefer@brasslantern.com> typed:
:I tried this again and got much better results for two-or-more element
:arrays, but singleton arrays were still getting subscripted as scalars.
:Investigation led me to this fragment of paramsubst():
:
:        if (isarr > 0 && !plan9 && (!aval || !aval[0])) {
:            val = dupstring("");
:            isarr = 0;
:        } else if (isarr && aval && aval[0] && !aval[1]) {
:            val = aval[0];
:            isarr = 0;
:        }
:
:Well, look at that.  If we have a singleton array, make it into a scalar.
:This doesn't have anything to do with multsub() at all!
:
:Does anybody remember why this code is here?  What part of the world is
:going to come crashing down if that "else if" clause gets deleted?

It's a pf artifact.  Looking in 2.00.03 sees it there in a slightly
different incantation but logically the same.
-- 
Geoff Wing   <gcw@pobox.com>            Mobile : (Australia) 0412 162 441
Work URL: http://www.primenet.com.au/   Ego URL: http://pobox.com/~gcw/

Re: Singleton arrays treated as scalars

[Sven Wischnowsky]

Bart Schaefer wrote:

> I tried this again and got much better results for two-or-more element
> arrays, but singleton arrays were still getting subscripted as scalars.
> Investigation led me to this fragment of paramsubst():
> 
>         if (isarr > 0 && !plan9 && (!aval || !aval[0])) {
>             val = dupstring("");
>             isarr = 0;
>         } else if (isarr && aval && aval[0] && !aval[1]) {
>             val = aval[0];
>             isarr = 0;
>         }
> 
> Well, look at that.  If we have a singleton array, make it into a scalar.
> This doesn't have anything to do with multsub() at all!
> 
> Does anybody remember why this code is here?  What part of the world is
> going to come crashing down if that "else if" clause gets deleted?

When buildin the patch I just sent, I stumbled over this, too. And no, 
I have no idea whence this came or what would happen, if...

Bye
 Sven


--
Sven Wischnowsky                         wischnow@informatik.hu-berlin.de