Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!sun-barr!newstop!male!anywhere.EBay.Sun.COM!me
From: me@anywhere.EBay.Sun.COM (Wayne Thompson - IR Workstation Support SE)
Newsgroups: comp.lang.perl
Subject: Re: Returning two lists
Message-ID: <6088@male.EBay.Sun.COM>
Date: 6 Apr 91 12:45:51 GMT
Sender: news@male.EBay.Sun.COM
Lines: 58

From pg 73 of the book "...the value of an array in a scalar
context is the length of the array"

Yes, your's is more efficient. Hope that helps.

Wayne

In article <1991Apr5.182305@sic.epfl.ch>, brossard@sic.epfl.ch (Alain Brossard EPFL-SIC/SII) writes:
| In article <6010@male.EBay.Sun.COM>, me@anywhere.EBay.Sun.COM (Wayne Thompson - IR Workstation Support SE) writes:
| || --- Alain Brossard writes ---
| ||    I want to return two lists from a subroutine
| || 
| || sub search {
| ||     local( @list, @whiteouts ) = @_;
| || (...)
| ||     return ( @list, @whiteouts );
| || # also tried
| || #   return ( (@list), (@whiteouts) );
| || }
| || 
| || (@list, @whiteouts) = do search( $dir, '' );
| || 
| || 	The only thing I get is that on return, @list
| || always contains the union of the returned lists.
| || -----------------------------
| | 
| | You could return enough information to decompose the lists...
| | 
| | return (scalar(@list), @list, @whiteouts);
| 
|   Will scalar(ARRAY) always return the size of the array?
| I didn't see that documented anywhere.
| 
| | Then recompose them on receipt...
| | 
| | @_ = &search(....);
| | @whiteouts = splice (@_, shift (@_));
| | @list = @_;
| | 
| | Wayne
| 
|   Thanks for pointing me out the splice fonction. I think
| the following code is a bit more efficient?
| 
| @whiteouts = do search( $dir, '' );
| @list = splice( @whiteouts, 0, shift(@whiteouts));
| 
|     @list can be potentialy huge, so I was really looking
| for the optimal way of doing this.  The best way would be to
| (shudder) use global variables, but this is out since the
| subroutine is recursive (and not tail-end recursive).
| 
| 
| -- 
| 
| Alain Brossard, Ecole Polytechnique Federale de Lausanne,
| 	SIC/SII, EL-Ecublens, CH-1015 Lausanne, Suisse
| brossard@sasun1.epfl.ch