Reusing variable names in different scopes

Question

As in the following example with $DimensionSwitch, I like to reuse the names of variables. I know $DimensionSwitch is lexically scoped, so it doesn't appear to cause any problems, but (1) might it cause problems somewhere that I don't know about and therefore (2) is it poor practice to reuse variable names in Perl?

my $DimensionSwitch = checkDimensions(\@coefficients,\@predictors);
sub checkDimensions{
    my @a1 = @{$_[0]};
    my @a2 = @{$_[1]};
    my $Size1 = @a1;
    my $Size2 = @a2;
    my $DimensionSwitch;
    if ($Size1 == $Size2){
        $DimensionSwitch = 1;
    }else{
        $DimensionSwitch = 0;
    }
    return $DimensionSwitch;
}

If it's scoped then it won't cause problems elsewhere, but it will be confusing, if not for you, then for someone else reading your code. Best avoided! — fugu
– fugu, Commented Jul 22, 2014 at 7:18

user3849273 · Accepted Answer · 2014-07-22 09:36:25Z

2

It shouldn't
It's not bad per se. It is bad if it makes more difficult to read code

and the code...

my $DimensionSwitch = int(@coefficients == @predictors);

answered Jul 22, 2014 at 9:36

user3849273

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2 Comments

Jim Davis Over a year ago

Neat, int to force 1/0 instead of 1/''.

user3849273 Over a year ago

It is there to play safe. I'm pretty sure the variable is checked on being truthy, not exactly 1 or 0. But I don't know the rest of author's code.

jordivador · Accepted Answer · 2014-07-22 09:39:13Z

1

It's really usefull use pragma 'use strict' in Perl. This pragma is not the cure for all but you could use also 'use warnings' and perl it self will advice you of many nasty things :)

http://perldoc.perl.org/strict.html

answered Jul 22, 2014 at 9:39

jordivador

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Comments

JRFerguson · Accepted Answer · 2014-07-22 11:30:55Z

1

Reusing variable names within a lexical scope isn't forbidden but can be confusing and create subtle maintenance headaches.

You can use Perl::Critic::Policy::Variables::ProhibitReusedNames as an analysis tool.

A nice web interface allows you to upload your code for analysis at varying degrees of brutality here.

answered Jul 22, 2014 at 11:30

JRFerguson

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