> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On
> Behalf Of Lloyd Sartor
> Sent: Wednesday, August 03, 2005 10:19 AM
> To: [EMAIL PROTECTED]
> Cc: [email protected]
> Subject: Re: Return to Sender (w/apologies to Elvis)
>
> [EMAIL PROTECTED] wrote on 08/03/2005 08:16:53 AM:
>
> > I have a subroutine which is supposed to return a reference to an
> > array. All this subroutine does is call another sub (i.e.: it's a
> > wrapper), which returns the array that the first sub then has to
> > return the reference to. Isn't there a one-liner way of doing this?
> > I was using:
> >
> > sub outer_sub {
> > @ret_ary = _inner_sub();
> > return( [EMAIL PROTECTED] );
> > }
> >
> > where the returned value from _inner_sub is an array:
> >
> > sub _inner_sub {
> > # create @inner_ret_ary. . .
> > return( @inner_ret_ary );
> > }
> >
> > which worked fine. But, when I tried to streamline
> outer_sub like this:
> >
> > return( \_inner_sub()); # _inner_sub just returns @
> >
> > with the same return value (an array) from _inner_sub, it fails.
>
> The one-liner attempt is returning a reference to the
> subroutine. You can
> create an anonymous list in outer_sub using the bracket
> syntax and return
> its reference:
>
> sub outer_sub {
> # @ret_ary = _inner_sub();
> # return( [EMAIL PROTECTED] );
> return([_inner_sub()]);
> }
When I play with the "outer_sub" return a little I got the following
results (from ActiveState build 638 on a MS Windows XP system):
# return [ _inner_sub() ];
# calls _inner_sub in a LIST context and returns a ref to an
anonymous array
# created from the returned list.
#
# return _inner_sub();
# return ( _inner_sub() );
# calls _inner_sub in a SCALAR context and so returns the length of
the list
# returned.
#
# return \_inner_sub();
# return \( _inner_sub() );
# calls _inner_sub in a LIST context and returns a reference to the
last
# element of the list.
>
> sub _inner_sub {
> @inner_ret_ary = (1,3,5,7,9);
> return( @inner_ret_ary );
> }
If "_inner_sub" is part of code that you "own" or control, it might be a
thought to consider using wantarry() to make it context-sensitive. Have
it return a reference to the array if called in a scalar context and the
contents of the array as a list if called in a list context. For
example:
sub _inner_sub {
# ... do whatever you do to build the array ...
if ( wantarray() ) { return @inner_ret_ary; }
else { return [EMAIL PROTECTED]; }
}
That might eliminate the need for the wrapper and may avoid the work and
memory usage for creating and populating yet another array value.
>
> $x = outer_sub();
> print "\$x = $x\n";
> print "[EMAIL PROTECTED] = @$x\n\n";
>
> ------------------------------------------------
> $x = ARRAY(0x1a4fea0)
> @$x = 1 3 5 7 9
>
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>
Gary L. Stump.,
Sr. Engineer, IS/OTS
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