RE: What is the function of BEGIN in perl
-Original Message-
From: Mr. Shawn H. Corey [mailto:[EMAIL PROTECTED]
Sent: Monday, May 01, 2006 7:36 PM
To: chen li
Cc: beginners@perl.org
Subject: Re: What is the function of BEGIN in perl
On Mon, 2006-01-05 at 15:32 -0700, chen li wrote:
Dear all,
Recently I read some source codes of perl modules. I
find some codes look like this:
BEGIN {..}
What is the function of BEGIN here?
BEGIN clauses are executed immediately after they are compiled. As
such,
they can be used to redirect the compilation of the remaining code. For
example, if you write a module that is dependant on the operating
system, that is, there is different code for different operating
systems, you could use BEGIN to load the appropriate subroutines:
#!/
package MyModule;
BEGIN {
if( $^O eq 'MSDos' ){
require 'MyModule::MSDos.pm';
}elsif( $^O eq 'MacOSX' ){
require 'MyModule::MacOSX.pm';
}else{
require 'MyModule::Generic.pm';
}
}
If the normal course of affairs, you would not need it. But if you do
need it, it is there. (In other words, don't worry about it unless all
else fails).
***
Doesn't the BEGIN and INIT constructs provide the same behavior?
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Re: What is the function of BEGIN in perl
Smith, Derek wrote: Doesn't the BEGIN and INIT constructs provide the same behavior? No. From `perldoc perlrun`: -c causes Perl to check the syntax of the program and then exit without executing it. Actually, it will execute BEGIN, CHECK, and use blocks, because these are considered as occurring outside the execution of your program. INIT and END blocks, however, will be skipped. -- __END__ Just my 0.0002 million dollars worth, --- Shawn For the things we have to learn before we can do them, we learn by doing them. Aristotle * Perl tutorials at http://perlmonks.org/?node=Tutorials * A searchable perldoc is at http://perldoc.perl.org/ -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/ http://learn.perl.org/first-response
RE: What is the function of BEGIN in perl
-Original Message- From: Mr. Shawn H. Corey [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 05, 2006 1:21 PM To: Perl Beginners Subject: Re: What is the function of BEGIN in perl Smith, Derek wrote: Doesn't the BEGIN and INIT constructs provide the same behavior? No. From `perldoc perlrun`: -c causes Perl to check the syntax of the program and then exit without executing it. Actually, it will execute BEGIN, CHECK, and use blocks, because these are considered as occurring outside the execution of your program. INIT and END blocks, however, will be skipped. -- __END__ Just my 0.0002 million dollars worth, --- Shawn For the things we have to learn before we can do them, we learn by doing them. Aristotle * Perl tutorials at http://perlmonks.org/?node=Tutorials * A searchable perldoc is at http://perldoc.perl.org/ ** Ok so what is the diff then? I search through all my emails, programming perl, perl best practices and PerlMonks but did not find anything. Derek Bellner Smith Unix Systems Engineer Cardinal Health Dublin, Ohio _ This message is for the designated recipient only and may contain privileged, proprietary, or otherwise private information. If you have received it in error, please notify the sender immediately and delete the original. Any other use of the email by you is prohibited. Dansk - Deutsch - Espanol - Francais - Italiano - Japanese - Nederlands - Norsk - Portuguese - Svenska: www.cardinalhealth.com/legal/email -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/ http://learn.perl.org/first-response
Re: What is the function of BEGIN in perl
Thanks very much for Anthiny and others for the
explanation.
Li
--- Anthony Ettinger [EMAIL PROTECTED] wrote:
basically, BEGIN { } is a block which gets called
whenever the script
begins.
On 5/1/06, chen li [EMAIL PROTECTED] wrote:
Dear all,
Recently I read some source codes of perl modules.
I
find some codes look like this:
BEGIN {..}
What is the function of BEGIN here?
Thank you,
Li
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What is the function of BEGIN in perl
Dear all,
Recently I read some source codes of perl modules. I
find some codes look like this:
BEGIN {..}
What is the function of BEGIN here?
Thank you,
Li
__
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RE: What is the function of BEGIN in perl
chen li wrote:
: Recently I read some source codes of perl modules. I
: find some codes look like this:
:
: BEGIN {..}
:
: What is the function of BEGIN here?
Read BEGIN, CHECK, INIT and END in the perlmod file.
HTH,
Charles K. Clarkson
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Re: What is the function of BEGIN in perl
basically, BEGIN { } is a block which gets called whenever the script
begins.
On 5/1/06, chen li [EMAIL PROTECTED] wrote:
Dear all,
Recently I read some source codes of perl modules. I
find some codes look like this:
BEGIN {..}
What is the function of BEGIN here?
Thank you,
Li
__
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
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Anthony Ettinger
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Re: What is the function of BEGIN in perl
On Mon, 2006-01-05 at 15:32 -0700, chen li wrote:
Dear all,
Recently I read some source codes of perl modules. I
find some codes look like this:
BEGIN {..}
What is the function of BEGIN here?
BEGIN clauses are executed immediately after they are compiled. As such,
they can be used to redirect the compilation of the remaining code. For
example, if you write a module that is dependant on the operating
system, that is, there is different code for different operating
systems, you could use BEGIN to load the appropriate subroutines:
#!/
package MyModule;
BEGIN {
if( $^O eq 'MSDos' ){
require 'MyModule::MSDos.pm';
}elsif( $^O eq 'MacOSX' ){
require 'MyModule::MacOSX.pm';
}else{
require 'MyModule::Generic.pm';
}
}
If the normal course of affairs, you would not need it. But if you do
need it, it is there. (In other words, don't worry about it unless all
else fails).
__END__
--
__END__
Just my 0.0002 million dollars worth,
--- Shawn
For the things we have to learn before we can do them, we learn by doing them.
Aristotle
* Perl tutorials at http://perlmonks.org/?node=Tutorials
* A searchable perldoc is at http://perldoc.perl.org/
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