Best way to pass a array to a function

vinoth.ree has asked for the wisdom of the Perl Monks concerning the following question:

Here which one is the efficient way of passing array to a function print_array

our @foo = ("ree1", "ree2", "ree3");
print_array(*foo);


my @foo = ("ree3","ree2","ree1");
print_array(\@foo);

sub print_array {
    local (*printarr) = @_;
    foreach my $val (@printarr) {
        print "$val\n";
    }
}
[download]

Vinoth,G

Comment on Best way to pass a array to a function Download Code

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Re: Best way to pass a array to a function by moritz (Cardinal) on Apr 27, 2009 at 12:20 UTC
Why don't you try it? Benchmark is your friend.	[reply]
Re: Best way to pass a array to a function by Marshall (Canon) on Apr 27, 2009 at 17:48 UTC
I would say in general, for reasons that are independent of performance, a lexical "my" variable is preferred over a package level "our" variable. Also besides scoping issues, a "my" variable is faster than a "local" variable. A shift is very slightly faster than a ~~"my $var = @_;"~~( missed parens! oops..(my $var)= @_;) when the sub has one arg passed to it. But in this case, I don't see how it could make much difference. If you are going to do some benchmarking, then I would suggest this code: `print_array2 (\@foo); sub print_array2 { my $array_ref = shift; print join ("\n", @$array_ref), "\n"; }` [download] I am curious as what you are doing as I've never seen a Perl program that was limited by speed of output (much more problematic is processing of the input data!). Print like all I/O is an expensive operation and time to do it usually dwarfs any calculation required to get the thing to print formatted. I would at least suggest adding the above code into your benchmarking - it will run very quickly.Of course, you can also try: `sub print_array2 { my $array_ref = shift; foreach (@$array_ref)) { print "$_\n"; } }` [download]	[reply] [d/l] [select]
Re: Best way to pass a array to a function by pemungkah (Priest) on Apr 27, 2009 at 21:07 UTC
I'd like to note that `foo` passes all* of the following: `$foo` `@foo` `%foo` `&foo` the filehandle `foo` `\@foo` passes only `@foo`. In terms of maintainability, go with the reference even if it's a teeny bit slower because someone maintaining code more complex than `print_array` might be confused as to which thing you really meant to pass in and use; worse, there's the possibility of accidentally using one of those variables in the subroutine and absentmindedly leaving off the `my` ... for which you will get no error message! Pass globs only when there's no other way to deal with the problem - and as of Perl 5.8 (at least), there's always a better way: references, or a filehandle in a lexical variable.	[reply] [d/l] [select]