Re: Why do I get a "used only once" warning here?

[ig]

Maybe something like the following would suffice:

package MyModule;

my %OneTime;

sub f {
    $OneTime{+__FILE__.' '.__LINE__} ||= (print("logging\n"), 1);
    return();
}
1;

[AnomalousMonk]

The OPer seems to want to control one-time printing/logging from outside the package/module, so that approach would not seem to do the trick. (Also, I don't know what the  + in front of the  __FILE__ is supposed to do.)

One can play around with caller to get a general solution closer to what I think the OPer wants:

Read more... (1409 Bytes)

[ig]

The OPer seems to want to control one-time printing/logging from outside the package/module

If one really wants a global in some other package, then...

package MyModule;
use strict;
use warnings;

sub f {
    $MyApp::OneTime{+__FILE__.' '.__LINE__} ||= (print("logging\n"), 1
+);
    return();
}
1;

[rovf]

I don't know what the + in front of the __FILE__ is supposed to do

In the current form, it has no meaning. It is a leftover from an earlier version, which read something like:

$MyApp::once{+__LINE__} ....

and so the + stayed there and when posting my problem, I copied it without much thinking. If you have only __LINE__ as key, the + is needed because __LINE__ is a bareword.