Variable declaration - C vs script style

[markoa]

Hello,

I've been wondering whether there are any differences in performance
when declaring variables within loops
comparing to all forward declarations. I'm mostly writing up to a few
hundred lines long scripts, but I need
relatively a lot variables, which look kind of ugly and IMO make the
script less readable when declared all
at the top. For example,

my ($var1, var2, var3, var4, var5, ...);
my (another set of variables);
while (...) {
$var1 = ...
$var2 = &foo($var1);
...
if ($var3) {
...
}

for ($var4 : ...)
}

vs

while (...) {
my $var1 = ...
my $var2 = &foo($var1);
...
my $var3 = ....;
if ($var3) {
...
}

for (my $var4 : ...)
}

Will the latter approach lead to more memory allocation and/or
significantly more work
for the garbage collector?

Marko

 

[J. Gleixner]

Hello,

I've been wondering whether there are any differences in performance
when declaring variables within loops

You know that you can test these things yourself, right?

perldoc Benchmark

 

[brian d foy]

I've been wondering whether there are any differences in performance
when declaring variables within loops
comparing to all forward declarations.

If that issue is a perfomance problem for you, then you're script is
already really, really fast or Perl is the wrong tool for you
(seriously). Don't even worry about it.

You should, however, limit variables just to the scope where you
actaully need them.