Benchmark Runs Only Once

InfiniteSilence has asked for the wisdom of the Perl Monks concerning the following question:

So I'm finally getting into the habit of benchmarking while I'm coding and I run across this article online. I like it but I hate to type the entire function, so I figure I'll read it from a file, like so:

use Benchmark;
my $code = '';
print "Enter number of code runs:\n";
my $runs = <STDIN>;
chomp ($runs);

print "Inline or load up code(1|2)?\n";
my $inline = <STDIN>;
chomp($inline);

if($inline == 1)
{
     $/ = "#END";
     print "Enter code block (end with #END):\n";
     $code = <STDIN>;
     chomp($code);
     print "\n...Testing...\n";
     timethis($runs, $code);
} else {
    my $file;
    my $func;
    print "Give me the file name: \n";
    $file = <STDIN>;
    chomp($file);
    $code = `cat $file`;

    eval($code);
    die $@ if $@;

    if($code=~m/sub\s+(\w+)/)
    {
    $func = $1;
    }
    no strict 'refs';
    print "\n...Testing...\n";
    timethis($runs, &$func);
}
[download]

In case you are interested, here is the dummy function it is trying to run:

sub manic {
     my $x = 0;
     for (0..50)
     {
         $x++;
     }

     print $x;
}
[download]

When I run this with the code option I get the following:

:)~> perl bmark.pl
Enter number of code runs:
2000
Inline or load up code(1|2)?
2
Give me the file name: 
test.al

...Testing...
51timethis 2000:  0 wallclock secs ( 0.00 usr +  0.00 sys =  0.00 CPU)
            (warning: too few iterations for a reliable count)
[download]

See? It just ran one time. If I manually type in the manic function's code it will run all 2000 times. What gives?

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Comment on Benchmark Runs Only Once Select or Download Code

Replies are listed 'Best First'.
Re: Benchmark Runs Only Once by Corion (Patriarch) on Sep 30, 2010 at 16:44 UTC
`&$func` does not give you a reference to the function, it calls the function: `> perl -wle "sub foo { print 'In foo' }; my $func='foo'; &$func" In foo` [download] Had you used strict, Perl would have prevented you from making this error. `> perl -Mstrict -wle "sub foo { print 'In foo' }; my $func='foo'; &$fu +nc" Can't use string ("foo") as a subroutine ref while "strict refs" in us +e at -e line 1.` [download]	[reply] [d/l] [select]
Re^2: Benchmark Runs Only Once by ikegami (Patriarch) on Sep 30, 2010 at 17:06 UTC
Using strict wouldn't have helped since he wants to get a reference to a symbol named in a variable. He should still use it, though, and just disable it where he needs it disable. `timethese(..., do { no strict 'refs'; \&$func });` [download] An alternative solution comes from the realisation that `timethese` can also take a string of Perl code. `timethese(..., $func.'()');` [download]	[reply] [d/l] [select]
Re: Benchmark Runs Only Once by JavaFan (Canon) on Oct 01, 2010 at 13:57 UTC
I'm finally getting into the habit of benchmarking while I'm coding You say this as if you think this is a good thing.	[reply]