Re: subroutine scope vs. tightest scope

[Tanktalus]

Improves readability by using "subroutine" scope? Far, far, FAR from it. Tightest scope possible improves readability because I don't have to go back to find out what else has played with this variable. It also means that when I figure out I don't need a variable any longer, I'm more likely to remove it - I've seen functions start with "my (<20 variables here>)" - and I notice one that looks out of place, and then can't find it being used anymore. I don't see nearly as many unused variables being declared when following tightest-scope-possible rules.

There is a reason why C++ started to allow declarations of local variables anywhere in a block, and not just at the top as its predecessor, C, did. Because it's more readable. And maintainable. (Well, that, and delayed construction of variables on the stack only made sense - forcing them all to the top of the block would be impossible.) And now, C allows it, too.

Mandatory declare-at-the-top semantics is going the way of the dodo. And for good reason. It was only ever there due to limitations of the compilers (allowing declarations anywhere is hard - especially in compiled languages with a stack). Now that even the compilers are being written in higher-level languages, with better automatic memory management, there's much less excuse in granting this type of flexibility for readability.

As for your question - yes, I know that works. And just to convince myself that I was right, I wrote a quick program to prove it ;-) Perl is more generous with where you can put "my" than you may think. You probably didn't know you could use it for the lexical filehandle in the first place:

#!/usr/bin/perl

use strict;
use warnings;

open my $fh, '<', $0;
chomp(my @lines = <$fh>);

print "[$_]\n" for @lines;

No lines starting with "my" - but, I do end up with both a lexical scalar (filehandle) and a lexical array.