Re^4: How to determine absolute path of current Perl file?

Just FYI, in a module "included" by use, executable statements in "file scope" are being run inside a begin block.

From the documentation for use, use Module LIST; is the same as:

BEGIN { require Module; Module->import( LIST ); }

The reason for using a BEGIN block in a module to execute some code before the module is completely compiled. Even without the BEGIN block, any "file scope" statements will get executed before anything after the use is compiled (then run).

As for the desirability of file scope code in a module, by design, Perl expects a "used" module to run init/sanity-check code at "use time". This is why most modules end with 1;. Perl is expecting the module to "return" a true value if everything is "A-Okay". Otherwise, a false value tells Perl something went wrong. Fetching the current working directory is a reasonable init action. Of course, if you are more comfortable using a BEGIN block, that's fine, too. TIMTOWTDI.

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Re^5: How to determine absolute path of current Perl file?
by Discipulus (Canon) on Feb 29, 2016 at 22:51 UTC

RonW

So using a BEGIN block inside a module to be used it's like to say: as soon as possible or even sooner.

#TestBegin.pm
use strict;
use warnings;

BEGIN{print "inside BEGIN in the module ",__FILE__,"\n"}
print "in the module ",__FILE__,"\n";

1;

perl  -e "print qq(in the program $0\n);BEGIN{print qq(BEGIN in the pr
+ogram $0\n)}" -MTestBegin

inside BEGIN in the module TestBegin.pm
in the module TestBegin.pm
BEGIN in the program -e
in the program -e
[download]


perl  -e "print qq(in the program $0\n);BEGIN{print qq(BEGIN in the pr
+ogram\n)}use TestBegin;"
BEGIN in the program
inside BEGIN in the module TestBegin.pm
in the module TestBegin.pm
in the program -e
[download]

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