Re^2: sort routines crossing package lines

Use prototypes on your sort subs so instead you would have sub caseless ($$) { lc($_[0]) cmp lc($_[1]) }

Yes, but I don't want to. perldoc -f sort claims that this introduces a performance hit and the application is already slow enough. I'm sorting lists with thousands of elements.

Or use the full name of $a and $b like this sub caseless { lc($main::a) cmp lc($main::b) }

That is only true if all uses of the sort routine are in package main. In this application this is not the case. This routine has to work when called from a number of different packages.

BTW, I'm not necessarily looking for an alternate implementation. What I'm looking for is understanding the reason why exporting $a and $b does not make this work, but exporting their typeglobs does.

--DrWhy

"If God had meant for us to think for ourselves he would have given us brains. Oh, wait..."

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Re^3: sort routines crossing package lines by ides (Deacon) on Nov 24, 2004 at 21:50 UTC
I've heard that prototypes slow down subroutines, however in practice I've found that it doesn't usually effect an application. I would suggest trying it to see. I believe the reason is they aren't just package variables, but "special package variables" according to `man perlvar`. Frank Wiles <frank@wiles.org> http://www.wiles.org	[reply] [d/l]
Re^3: sort routines crossing package lines by TomDLux (Vicar) on Nov 25, 2004 at 16:51 UTC
According to other monks' messages, below, you can sort short lists in microseconds or nanoseconds. So even though your lists have thousands of elements, I doubt that sorting is the cause of your speed concerns. Profile your program. I bet you'll find huge whacks of time spent copying arrays in a function call in an inner loop, where you should be passing a reference, or some other efficiency error. Or it might be your algorithmn that needs some re-thinking. Are you processing things in an item-by-item loop, when you could leave Perl to process the whole set at once? -- `TTTATCGGTCGTTATATAGATGTTTGCA`	[reply]
Re^4: sort routines crossing package lines by DrWhy (Chaplain) on Nov 26, 2004 at 14:52 UTC
This is a good point. I actually believe the big time hog is the large number of separate (and in some cases rather complex) queries made on the backend database. There may be some issues with passing/assigning arrays/hashes, but I've quashed alot of things like that already with no humanly noticeable improvement in speed. As for the impact of prototyped vs unprototyped sort routines I timed a portion of the code that does a lot of sorting with each version. The prototyped version added about a hundredth of a second to execution time (1.371 vs 1.382 seconds). So I've gone with the more straightforward prototyped implementation, ignoring the minute slowdown. --DrWhy "If God had meant for us to think for ourselves he would have given us brains. Oh, wait..."	[reply]