Re^3: Hacking Perl Code

> Doing this i discovered that my solution executes even less code than the perl -c -d:TraceUse script.pl one.

Could you please elaborate what you mean with less code?

Can you provide an example showing the difference?

TraceUse hooks into @INC with a callback like recently discussed.

With this approach its even possible to report before anything is included and to avoid the import.

Cheers Rolf

( addicted to the Perl Programming Language)

Comment on Re^3: Hacking Perl Code

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Re^4: Hacking Perl Code by Discipulus (Canon) on Apr 09, 2014 at 11:39 UTC
Dear LanX, i only meant, as explained in the update of the original post that my solution only executes any `BEGIN` block and no more, while with `perl -c -d:TraceUse script.pl` all the `BEGIN UNITCHECK CHECK` blocks are executed. I was wrong (so thanks for your question), because my code also executes any `END` blocks and even other `UNITCHECK` already present, because those blocks run LIFO. Here some code to demonstrate the concept. With a script called `test_of_executed_code.pl` as follow: `BEGIN{print qq(1-begin\n)}; UNITCHECK {print qq(2-unitcheck\n)}; CHECK {print qq(3-check\n)}; INIT {print qq(4-init\n)}; print qq(5-main\n); END{print qq(6-end\n)};` [download] You can now compare the two solutions: `some_win>perl -c -d:TraceUse test_of_executed_code.pl 1-begin 2-unitcheck 3-check Modules used from test_of_executed_code.pl: test_of_executed_code.pl syntax OK` [download] while with my script you'll see: `some_win>perl used_modules.pl test_of_executed_code.pl 1-begin 2-unitcheck strict 1.04 warnings 1.12 6-end` [download] The only way i found to prevent the `END` blocks to be executed is to change, in the `UNITCHECK` part of the original script, `exit;` with an ugly `exec qq(perl -e "exit");` that produces: `some_win>perl used_modules.pl test_of_executed_code.pl 1-begin 2-unitcheck strict 1.04 warnings 1.12` [download] But, considering the LIFO aptitude of the `UNITCHECK` blocks, i can do it better and change `eval $begin.$content;` with `eval $content.$begin;` producing: `some_win>perl used_modules.pl test_of_executed_code.pl 1-begin strict 1.04 warnings 1.12` [download] Thanks for the opportunity to learn something more. L* There are no rules, there are no thumbs.. Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.	[reply] [d/l] [select]
Re^5: Hacking Perl Code by LanX (Saint) on Apr 09, 2014 at 17:06 UTC
Well OK I see, you exit before CHECKs are executed and -c does all UNITCHECKs and CHECKs. But please be aware that any BEGIN and UNITCHECK within a required module is executed, so you are only disabling CHECK and other UNITCHECKS on the top level script. As I said, IMHO does Devel::TraceUse have the more flexible and extendable approach, because it catches all includes before they are done (and immediately printing a nested tree output) You are parsing the (hopefully unmanipulated) entries from %INC at the top-level. Both approaches have their pro and cons... :) update your approach is not much different from a source filter, so if you consider to release it as a use-able module you could implement it that way. But please be aware that both approaches have to deal with trailing __DATA__ and __END__ sections when appending (instead of prepending) a UNITCHECK. Cheers Rolf ( addicted to the Perl Programming Language)	[reply]
Re^6: Hacking Perl Code by Discipulus (Canon) on Apr 09, 2014 at 19:39 UTC
Thanks again LanX, you are becoming my teacher in elenctic method.. ;=) My attempt is only to show something i discovered and that fascinate me, as everytime with Perl. In a 'reinvent the wheel' style as a way to learn. As you can guess from my signature i would use Devel::TraceUse in a real project. Your comment are correct. I do not think to release something, may be usefull for me to investigate what a source filter is. When i was on my motorbike, 20 minutes after last post, i thought to the `__DATA__` and `__END__` side effect. See you at next question, i hope. L* There are no rules, there are no thumbs.. Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.	[reply] [d/l] [select]

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