I put the and ++$i there to stop the scalar keys %hash being optimised away for being in a void context:
[0] Perl> %a = 1..2e6; %b = 1..2e6;;
[0] Perl> cmpthese -1, {
A=>q[ scalar keys %a and ++$i for 1 .. 10000 ],
B=>q[ scalar keys %b for 1 .. 10000 ]
};;
Rate A B
A 804/s -- -26%
B 1087/s 35% --
A problem I've been bitten by with other useless statements in void contexts.
And because it is far cheaper than an assignment:
[0] Perl> cmpthese -1, {
A=>q[ scalar keys %a and ++$i for 1 .. 10000 ],
B=>q[ my $x = scalar keys %b for 1 .. 10000 ]
};;
Rate B A
B 658/s -- -19%
A 812/s 24% --
and therefore less of a bias to the test.
Do you have a better way to deal with these issues?
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.
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