Re^2: Efficiency of map vs. more verbose basic/fundamental code

I find statement modifiers to be the clearest way to write code, but maybe I'm just used to them. Still, I'm having trouble seeing why turning a standard for loop into a statement modifier cuts down on the memory usage. Why are examples A and B below different? Is it that the parentheses cause a list to be created in memory? Would example C be as bad as A?

# A
for ( sort keys %h ){
  dostuffwith($_);
}

# B
dostuffwith($_) for sort keys %h;

# C
dostuffwith($_) for (sort keys %h);
[download]

I guess I need to learn to benchmark memory usage.

Aaron B.
Available for small or large Perl jobs; see my home node.

Comment on Re^2: Efficiency of map vs. more verbose basic/fundamental code Download Code

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Re^3: Efficiency of map vs. more verbose basic/fundamental code by BrowserUk (Patriarch) on Oct 05, 2012 at 12:21 UTC
Still, I'm having trouble seeing why turning a standard for loop into a statement modifier cuts down on the memory usage. I didn't suggest it did. Only that it reduced the memory requirement compared to the map variant; and sourcecode/mindspace compared to the standard for loop. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' 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. RIP Neil Armstrong	[reply]
Re^4: Efficiency of map vs. more verbose basic/fundamental code by aaron_baugher (Curate) on Oct 05, 2012 at 16:18 UTC
Ah, my misunderstanding, I see that you didn't suggest what I was assuming. I agree; the statement modifier form uses less mindspace for me too. Aaron B. Available for small or large Perl jobs; see my home node.	[reply]