Re: sub argument passing? (TIMTOWTDI)

in reply to sub argument passing? (TIMTOWTDI)

There is another approach to this problem: prototyping.

#!/usr/bin/perl
use warnings;
use strict;

#prototyped to explicitly state acceptable arguments

sub addstuff($$$);

my $D=4;
my $E=3;
my $F=2;

#gives error if too few or too many arguments
#(or arguements of wrong type)

my $result = addstuff $D, $E, $F;

print $result."\n";

#prototyped to match

sub addstuff($$$){
        my $A=shift;
        my $B=shift;
        my $C=shift;
        return $A+$B+$C;
}
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Re^2: sub argument passing? (TIMTOWTDI) by AnomalousMonk (Archbishop) on Sep 17, 2012 at 21:04 UTC
`#prototyped to explicitly state acceptable arguments sub addstuff($$$); ... #gives error if too few or too many arguments #(or arguements of wrong type)` [download] OTOH: `>perl -wMstrict -le "my @ra = (99 .. 199); ;; sub S ($$$) { my $A = shift; my $B = shift; my $C = shift; ;; return $A + $B + $C; } ;; print S 1, 2, @ra; " 104` [download] Maybe better read Far More than Everything You've Ever Wanted to Know about Prototypes in Perl -- by Tom Christiansen first, then generally avoid prototypes.	[reply] [d/l] [select]
Re^3: sub argument passing? (TIMTOWTDI) by temporal (Pilgrim) on Sep 17, 2012 at 21:45 UTC
Thanks AnomalousMonk, I am following your advice and already seeing some issues that I'll run into with using Perl's prototyping such as it is. 'Enjoyable light reading' indeed, protist! Maybe just enjoyable ;) ^{Strange things are afoot at the Circle-K.}	[reply]
Re^2: sub argument passing? (TIMTOWTDI) by temporal (Pilgrim) on Sep 17, 2012 at 14:58 UTC
Cool, didn't know that Perl supported function prototyping. Looks a bit quicker and dirtier than using Params::Check - fewer filtering options, no default values, etc. I am gravitating towards creating a separate file which would contain all of my function prototypes and then I would `require` that in my module. My module has quite a few functions so this might be the easiest way to keep track of them all and have a single point of change rather than having to track down all that template-building legwork within the subroutines themselves that Params::Check requires. Not quite as legible, though. And to heed the docs warning, I could get into trouble writing prototypes for already written functions. So I'll have to do a little checking to make sure I'm not doing anything too silly with how arguments are being passed and unpacked. Anyway, thanks for pointing this out protist =) ^{Strange things are afoot at the Circle-K.}	[reply] [d/l]
Re^3: sub argument passing? (TIMTOWTDI) by choroba (Cardinal) on Sep 17, 2012 at 15:02 UTC
Before you decide to go this route, read Far More than Everything You've Ever Wanted to Know about Prototypes in Perl -- by Tom Christiansen carefully. لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply]
Re^4: sub argument passing? (TIMTOWTDI) by protist (Monk) on Sep 17, 2012 at 16:13 UTC
This should provide some enjoyable light reading. :P Thank you choroba.	[reply]
Re^3: sub argument passing? (TIMTOWTDI) by AnomalousMonk (Archbishop) on Sep 17, 2012 at 21:10 UTC
Cool, didn't know that Perl supported function prototyping. It doesn't. It's more like 'function argument context prototyping'. Please read the highly recommended Far More Than...	[reply]
Re^3: sub argument passing? (TIMTOWTDI) by protist (Monk) on Sep 17, 2012 at 16:11 UTC
You are welcome. :)	[reply]

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