Re (tilly) 1: Efficiency and overhead of subs

[tilly]

If you are into tight code that doesn't waste memory, then Perl is the wrong language for you.

Perl code routinely takes of several times the space and runs at a small fraction of the speed of an equivalent C program. There is nothing you can do about that other than to take up a language whose philosophy on life more closely matches your own. And if you are programming a CGI, the overhead of starting Perl itself is likely to dwarf the puny effects of your modularizing your code (which is unfortunately not free, though it is pretty cheap).

But that said, I strongly recommend that you read the chapter from Code Complete on Optimization. As he says there at length, when it comes to optimization, don't lose the forest for the trees. Concentrate on sane, understandable code. Don't worry about efficiency. And then in the time you save with good development practices, profile and optimize what needs to be optimized.

Unless you are working on simple, fast code which has to work in embedded chips, and admittedly some do, this advice results in a better development balance, and on real projects is ironically likely to wind up with faster code than people who micro-optimize from the start.

So if you have a real programming problem and Perl is a fit, then don't worry about overhead. Program sanely, try not to be stupid, pick decent algorithms, and when you are done, take Devel::DProf out for a spin if need be.

[HamNRye]

Actually, you might want to spend more time thinking about how your perl will run, not how it's written. If you are writing a CGI, you can use mod_perl on apache, Perl for Isapi on IIS, etc...

Also, I have found that using Perl2Exe can dramatically speed up a script that gets started often by eliminating the compile time.

I guess the point is that within reason, programming practice has a lot less to do with efficiency than run time implementation. Welcome to the world of interpreted languages.

That all said, use references, and avoid large hashes.

Hammy
Nothing4sale.org