in reply to Re^5: Error handling in chained method calls
in thread Error handling in chained method calls

Wow, I'm impressed.

An idealized benchmark shows only a 25% gain by memoizing, so I agree, it doesn't worth it.

            Rate  classic memoized
classic  75415/s       --     -19%
memoized 93110/s      23%       --

[download]
 
use strict;
 
my $obj={};
bless $obj,"Class";
 
sub classic {
  $obj->meth0->meth1->meth2->meth3->meth4->meth5->meth6->meth7->meth8-
+>meth9;
}
 
my $ref0=$obj->can("meth0");
my $ref1=$obj->can("meth1");
my $ref2=$obj->can("meth2");
my $ref3=$obj->can("meth3");
my $ref4=$obj->can("meth4");
my $ref5=$obj->can("meth5");
my $ref6=$obj->can("meth6");
my $ref7=$obj->can("meth7");
my $ref8=$obj->can("meth8");
my $ref9=$obj->can("meth9");
 
sub memoized {
  $obj->$ref0->$ref1->$ref2->$ref3->$ref4->$ref5->$ref6->$ref7->$ref8-
+>$ref9;
}
 
use Benchmark qw/cmpthese/;
 
cmpthese(1E6,
     {
      classic  => \&classic,
      memoized => \&memoized, 
     });
 
 
package Class;
 
sub meth0 { $_[0] }
sub meth1 { $_[0] }
sub meth2 { $_[0] }
sub meth3 { $_[0] }
sub meth4 { $_[0] }
sub meth5 { $_[0] }
sub meth6 { $_[0] }
sub meth7 { $_[0] }
sub meth8 { $_[0] }
sub meth9 { $_[0] }

[download]

Cheers Rolf

Replies are listed 'Best First'.
Re^7: Error handling in chained method calls
by BrowserUk (Patriarch) on Oct 25, 2010 at 03:08 UTC
    An idealized benchmark

    Hm. I'm not sure that "idealized" really described your benchmark. And neither does "memoized"--more like "hard-coded".

    Are you really suggesting that every user of every class should build a lexical cache of every method for each class they use, in each package they use it, and then hard-code all their method calls in terms of that lexical cache?

    I've removed your hard-coded version as unrealistic, and replaced with paranoid() reflecting the OPs suggested methodology. I've also added a realistically memoised version of that suggestion to show that it doesn't help: 

    use strict;

my $obj = Class->new;

sub classic {
  $obj->meth0->meth1->meth2->meth3->meth4->meth5->meth6->meth7->meth8-
+>meth9;
}

sub paranoid {
    $obj and ref $obj and my $ref0 = $obj->can('meth0');
    $obj and ref $obj and my $ref1 = $obj->can('meth1');
    $obj and ref $obj and my $ref2 = $obj->can('meth2');
    $obj and ref $obj and my $ref3 = $obj->can('meth3');
    $obj and ref $obj and my $ref4 = $obj->can('meth4');
    $obj and ref $obj and my $ref5 = $obj->can('meth5');
    $obj and ref $obj and my $ref6 = $obj->can('meth6');
    $obj and ref $obj and my $ref7 = $obj->can('meth7');
    $obj and ref $obj and my $ref8 = $obj->can('meth8');
    $obj and ref $obj and my $ref9 = $obj->can('meth9');
    $obj->$ref0->$ref1->$ref2->$ref3->$ref4->$ref5->$ref6->$ref7->$ref
+8->$ref9;
}

my %memo;
sub memoized {
    $obj and ref $obj and my $ref0 = $memo{ meth0 } || $obj->can('meth
+0');
    $obj and ref $obj and my $ref1 = $memo{ meth1 } || $obj->can('meth
+1');
    $obj and ref $obj and my $ref2 = $memo{ meth2 } || $obj->can('meth
+2');
    $obj and ref $obj and my $ref3 = $memo{ meth3 } || $obj->can('meth
+3');
    $obj and ref $obj and my $ref4 = $memo{ meth4 } || $obj->can('meth
+4');
    $obj and ref $obj and my $ref5 = $memo{ meth5 } || $obj->can('meth
+5');
    $obj and ref $obj and my $ref6 = $memo{ meth6 } || $obj->can('meth
+6');
    $obj and ref $obj and my $ref7 = $memo{ meth7 } || $obj->can('meth
+7');
    $obj and ref $obj and my $ref8 = $memo{ meth8 } || $obj->can('meth
+8');
    $obj and ref $obj and my $ref9 = $memo{ meth9 } || $obj->can('meth
+9');
    $obj->$ref0->$ref1->$ref2->$ref3->$ref4->$ref5->$ref6->$ref7->$ref
+8->$ref9;
}

use Benchmark qw/cmpthese/;

cmpthese(1E6,
     {
      classic  => \&classic,
      paranoid => \&paranoid,
      memoized => \&memoized,
     });


package Class;

sub new { bless {}, $_[0] }

sub meth0 { $_[0] }
sub meth1 { $_[0] }
sub meth2 { $_[0] }
sub meth3 { $_[0] }
sub meth4 { $_[0] }
sub meth5 { $_[0] }
sub meth6 { $_[0] }
sub meth7 { $_[0] }
sub meth8 { $_[0] }
sub meth9 { $_[0] }

__END__
C:\test>junk
             Rate memoized paranoid  classic
memoized 101102/s       --      -9%     -65%
paranoid 111099/s      10%       --     -61%
classic  286123/s     183%     158%       --

    [download]

    I was tempted to add a Moose example, but that would be just like bear-baiting.

    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
[d/l]
      I was tempted to add a Moose example, but that would be just like bear-baiting.

      A Moose example wouldn't be any different because you are not hitting upon the places where Moose is slow. A method call in Moose is the same as a method call in a vanilla Perl object, and Moose does not override &can, seems like you are just trolling Moose again. Oh well.

      -stvn
[reply]
[d/l]
        A method call in Moose is the same as a method call in a vanilla Perl

        Wouldn't the normal response to such a requirement be to use the before or after or around keywords to add pre and/or post conditions to the methods?

        And wouldn't those extra layers have some performance penalty?

        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
      > An idealized benchmark

      > >Hm. I'm not sure that "idealized" really described your benchmark. And neither does "memoized"--more like "hard-coded".

      It's called a lower bound approximation.

      And BTW I also idealized by avoiding any inheritance.

      Cheers Rolf

[reply]
        It's called lower bound approximation.

        In this case, I'd call it out-of-bounds :)

        And I also idealized by avoiding any inheritance.

        Within-bounds. Not all classes use inheritance.

        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]

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