Re^3: Loading all files in a dir with use via for loop

Your question is a little confusing, but I will do my best. It seems like you are trying to see if certain functions have been exported into your main script.

First step, read up on packages. Your script should have the package name 'main' (you might even want to get in the habit of specifying package main;). Once you realize this, you can use the standard method for checking to see if a package has a particular method/subroutine available.

All packages are descendants of UNIVERSAL, so you can use its can method, which looks like this:

PackageName->can('sub_name');
[download]

So, if you're in the main package:

$PAGE = "test_function_a";
eval "$PAGE" if main->can($PAGE);
[download]

However, this is probably not what you want to do. Executing function names stored in variables can be rather dangerous, and you should understand the risks before doing so. I don't know what problem you're trying to solve, but perhaps a solution like a rudimetary dispatch table is better suited:

my %dispatch = (
   'test_function_a' => \&test_function_a,
   'test_function_b' => \&test_function_b,
);

foreach my $func ( qw'test_function_a test_function_b' ) {
   die "Package main doesn't seem able to '$func'" unless main->can($f
+unc);
   $dispatch{$func}->();
}
[download]

This avoids some of the issues with eval, and might even be faster.

<-radiant.matrix->
Larry Wall is Yoda: there is no try{} (ok, except in Perl6; way to ruin a joke, Larry! ;P)
The Code that can be seen is not the true Code
"In any sufficiently large group of people, most are idiots" - Kaa's Law

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Re^4: Loading all files in a dir with use via for loop by Delusional (Beadle) on Sep 29, 2005 at 13:27 UTC
Thanks radiant.matrix, Thats working with the exception of the error message (forgot the package command in one of the files thus it caused problems (all files are part of main as they were orginally in the main file and only stripped out and put into smaller ones to make reading and editing easier)).... . Specifically, I'd like the eval (prefer eval over the dispatch in this situation), to call nopageerror (which is in the main package). I've tried adding else commands to the if, however, as my luck this week has been, its kicking out with an error (probibily because it not valid, didn't find a ref to useing if-then-else in eval's, but thought I'd try anyway). The reason for calling nopageerror, is to display a useful information in the browser as well as generate special logs that arn't quite as cryptic as the Perl error messages and Apache logs... What would I have to do to be able to eval the var, if the var is a function, execute it, if not, call the sub routine to issue the error message about the missing function. This is probibily so simple that I'm over looking it...	[reply]
Re^5: Loading all files in a dir with use via for loop by Delusional (Beadle) on Sep 29, 2005 at 14:09 UTC
Never mind, problem solved by using or. Geez, did I over look the obvious... For those that need it..... `eval "$PAGE" if main->can($PAGE) or main->nopageerror;` [download] Thanks again radiant.matrix for the push in the right direction.	[reply] [d/l]
Re^6: Loading all files in a dir with use via for loop by radiantmatrix (Parson) on Sep 29, 2005 at 19:57 UTC
~~That does work because of the super-low-precedence of 'or'.~~Actually, it doesn't work. The `if` wants to evaluate all of the following expression. It's not very readable, ~~though~~either.~~: someone who doesn't understand the lower-precedence-ness of 'or' (compared to '\|\|', especially). To them it would look like you should~~It will try to eval $PAGE if one of the two or statements is true. Also, you don't need to specify main-> for nopageerror. For clarity, I suggest one of these: `# whoops, syntax errors, thanks to Roy Johnson ## ( eval "$PAGE" if main->can($PAGE) ) or nopageerror; ## or... #( eval "$PAGE" if main->can($PAGE) ) # or nopageerror; ## or... if ( main->can($PAGE) ) { eval $PAGE } else { nopageerror }` [download] Updates: 2005-09.Sep-30 : fixed stupid errors as pointed out by Roy Johnson. Don't code without coffee, kids! :-) <-radiant.matrix-> Larry Wall is Yoda: there is no `try{}` (ok, except in Perl6; way to ruin a joke, Larry! ;P) The Code that can be seen is not the true Code "In any sufficiently large group of people, most are idiots" - Kaa's Law	[reply] [d/l]
Re^7: Loading all files in a dir with use via for loop by Roy Johnson (Monsignor) on Sep 29, 2005 at 20:33 UTC
Re^7: Loading all files in a dir with use via for loop by Delusional (Beadle) on Sep 30, 2005 at 13:02 UTC