>>>>> "MR" == Matteo Riva <mura...@gmail.com> writes:
MR> On Thu, Sep 17, 2009 at 5:56 PM, Uri Guttman <u...@stemsystems.com> wrote: >> hopefully that explains it. MR> Unfortunately, not really :) so ask a more detailed question! MR> I *know* about the symbol table and typeglobs, but I yet have to MR> *understand* how it all works, and how to use it. you don't need to use it in general. munging the symbol table isn't a newbie thing. by far the most common use is in exporting symbol from a module and that is handled by the exporter module so you never see any globs. MR> My first question here - before everything else - is: why subs to just MR> return an integer? Why not directly use the number itself? symbolic constants are named vs a raw number. this is common in most langs, to not hardwire numbers because if the number changes, you only change it in one place and not everywhere. also it makes for more readable code. this is an ancient design idea but perl implements it with constant subs (and that requires a prototype with no args to allow the compiler to optimize it). note that perl will do compile time conversion of constant subs to the actual number so there is no slowdown in using them. as for file::slurp, note that i need the symbols because in some cases their values vary from platform to platform. imagine having to check which platform's numbers to use in each case! here i do that one time at compile time and it works. as i said, i needed to do that hack since older perls didn't define those constants and i needed symbols for the above reasons. uri -- Uri Guttman ------ u...@stemsystems.com -------- http://www.sysarch.com -- ----- Perl Code Review , Architecture, Development, Training, Support ------ --------- Gourmet Hot Cocoa Mix ---- http://bestfriendscocoa.com --------- -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
