syntax in the sub

steph_bow has asked for the wisdom of the Perl Monks concerning the following question:

Dear Monks,

This is a trivial test but I would like to know if you advise to use different names in the sub from the ones used in the main part of the script. Here I have used $day in the main part and $date in the sub.Thanks a lot !

Here is my code

#! usr/bin/perl -w
use strict;
# la librairie appelée sert à utiliser les fonctions move et copy 
use File::Copy;
use warnings;
use File::Find;
use diagnostics;

BEGIN {
  open(STDERR, ">stderr.log")
    or die "Failed to open log file";
}

sub general_per_day_process{
    my $date = shift @_;
    print STDOUT "the date is $date\n";
}
    

my @ALL_WEEK_DAYS = (20061022, 20061023);

################# selection of the week ############################


my $day;

foreach $day(@ALL_WEEK_DAYS){
    print STDOUT "the day is $day\n";
}

foreach $day(@ALL_WEEK_DAYS){
    general_per_day_process($day);
}    

close STDERR;
[download]

Comment on syntax in the sub Download Code

Replies are listed 'Best First'.
Re: syntax in the sub by Narveson (Chaplain) on Apr 29, 2008 at 14:16 UTC
No, I do not advise using different names in the sub from the ones used in the main part of the script. The whole point of lexically scoped names is that a name in one scope does not interfere with a name in a different scope. The programmer can stop worrying about where else a name may have been used, because it doesn't matter. A note about scope Instead of `my $day; foreach $day(@ALL_WEEK_DAYS){ ... }` [download] you should declare your loop variable as part of the `foreach` statement: `foreach my $day(@ALL_WEEK_DAYS) { ... }` [download]	[reply] [d/l] [select]
Re: syntax in the sub by jethro (Monsignor) on Apr 29, 2008 at 14:57 UTC
As your example perfectly demonstrates, using different names can be quite misleading. Someone reading your script would probably expect to see 'Monday' or '1' in a variable called $day, whereas $date is the name that leads directly to the right idea. Descriptive variable names are a blessing. Make the most of it.	[reply]


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syntax in the sub

A note about scope