BEGIN block question

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

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Re: BEGIN block question by FunkyMonk (Bishop) on Jun 05, 2007 at 21:45 UTC
From permod: A BEGIN code block is executed as soon as possible, that is, the moment it is completely defined, even before the rest of the containing file (or string) is parsed. Your BEGIN block in test.pl is executed before your `use MyApp::Conf qw/APP_NAME/;` statement	[reply] [d/l]
Re^2: BEGIN block question by Anonymous Monk on Jun 05, 2007 at 21:59 UTC
you seemed to refer to the code that has `use MyApp::Conf qw/APP_NAME/;` outside the BEGIN block. in that case, after the BEGIN block run, $ENV{APP_NAME} is set and `use MyApp::Conf qw/APP_NAME/;` runs fine. it is only problem whei put `use MyApp::Conf qw/APP_NAME/;` inside the block as the last line.	[reply] [d/l] [select]
Re^3: BEGIN block question by FunkyMonk (Bishop) on Jun 05, 2007 at 22:20 UTC
While everything I wrote is correct, it just didn't answer your question at all. Sorry.	[reply]
Re: BEGIN block question by Anonymous Monk on Jun 05, 2007 at 21:41 UTC
sorry. the above code actually works. it failed when i put the use MyApp::Conf qw/APP_NAME/; inside the BEGIN block.	[reply]
Re^2: BEGIN block question by kyle (Abbot) on Jun 05, 2007 at 21:55 UTC
The reason it fails inside the `BEGIN` block is that the use of `MyApp::Conf` happens while the `BEGIN` block is being compiled, but the assignment to `%ENV` happens after the `BEGIN` block is compiled (i.e., at the `BEGIN` block's "run time"). If you put it after the `BEGIN` block, then the compilation (`use`) of `MyApp::Conf` happens after the `BEGIN` block has executed (and the assignment to `%ENV` has happened).	[reply] [d/l] [select]
Re^3: BEGIN block question by Anonymous Monk on Jun 05, 2007 at 22:02 UTC
thank you. that's very clear. i totally forgot that assignment happens at runtime and `use` happens at compiled time. hence the failure in the BEGIN block.	[reply] [d/l]
Re^2: BEGIN block question by merlyn (Sage) on Jun 05, 2007 at 21:54 UTC
Hmm. the above code actually works. and yet... `use warnigns;` [download] One of those two postings is a lie. Hint: cut-n-paste, please. Don't retype. -- Randal L. Schwartz, Perl hacker	[reply] [d/l]
Re^2: BEGIN block question by ikegami (Patriarch) on Jun 05, 2007 at 23:42 UTC
This came up twice very recently. The problem is that the `use` statements in the `BEGIN` block finish compiling before the `BEGIN` block does (seeing as the `BEGIN` block finishes later in the sources), so they get executed first. In short, you want `use FindBin qw($RealBin); use lib "$RealBin/lib/"; BEGIN { $ENV{APP_ROOT} = $RealBin; } use MyApp::Conf qw/APP_NAME/;` [download] Previous thread #1 Previous thread #2	[reply] [d/l] [select]