I find interpolating/concatanating of any complexity mainly looks messy. Try to add dereferencing hash/array refs or method calls to the mix and it gets worse. I get on better with a template so I often press sprintf into service. 
$hotfix = sprintf(
  q{%s_%s_%s_%s.zip},
  $app,
  $mod,
  $bld,
  $hf,
);

[download]
Expressions, ternaries, refs, method calls, etc. will fit nicely while still, imo, being readable.

Although in the second (simple) case 

$fullpath = join(q{/}, $dir, $filename);

[download]
looks better to me.

ymmv

In reply to Re: Is there a reason to use "join" instead of just using the period? by wfsp
in thread Is there a reason to use "join" instead of just using the period? by qazwart

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