CGI/Perl Guide | Learning Center | Forums | Advertise | Login Site Search: in Perl Guide PerlGuru Forums Learning Ctr

	MAIN INDEX	SEARCH POSTS	WHO'S ONLINE	LOG IN

Home: Perl Programming Help: Intermediate: Significance of ::_

abhinandantn New User Aug 13, 2012, 6:13 AM Post #1 of 5 (4625 views) Significance of ::_ Can't Post I came across a code where in they had used a code similar to below my $code= \@{"::_<$file"}; i understood that the above code reads each line of the $file and references each line as index and we can access each of those line as $code->[10]. what i did not get here is, what is the use of ::_ here, what is it doing to the input from the file.

BillKSmith Veteran Aug 14, 2012, 8:02 AM Post #2 of 5 (4612 views) Re: [abhinandantn] Significance of ::_ [In reply to] Can't Post This does not appear to make sense to me. Perhaps you could post a working subset of the code. I believe that the statement is creating a hard reference to an array which is referenced by a symbolic reference. (The double quotes cause $file to be interpolated into the string. The two colins at the beginning of that string say that the symbolic reference uses the main:: symbol table.) The function of the remaining characters "_>" remains a mystery. The use of 'my' is also strange. It is seldom used without 'use strict;' which would prohibit the use of symbolic reference. Good Luck, Bill

abhinandantn New User Aug 14, 2012, 8:10 AM Post #3 of 5 (4610 views) Re: [BillKSmith] Significance of ::_ [In reply to] Can't Post I saw this code in Trace.pm present in perl/lib/Devel

BillKSmith Veteran Aug 15, 2012, 6:39 AM Post #4 of 5 (4574 views) Re: [abhinandantn] Significance of ::_ [In reply to] Can't Post This code is beyond my skill level. I can safely make a few more observations. Note that the next statement is a print to STDERR. This statement clearly prints the lines described in the DESCRIPTION section of the POD in the same file. From this, we can infer that $code is a reference to an array which contains the source code of the program being debugged, $l is the number of the line being executed and $f contains the name of that program (apparently preceded by '/.'). Also note that "use strict' is not in effect. Both of these observations support my previous comments about a symbolic reference. I still cannot figure out the purpose of the special characters in the symbolic reference. Good Luck, Bill

rovf Veteran Aug 16, 2012, 12:34 AM Post #5 of 5 (4551 views) Re: [BillKSmith] Significance of ::_ [In reply to] Can't Post Though seldom used, Perl variable names can contain virtually any combination of characters (AFIK, variable names consisting of digits only are forbidden). I guess the purpose is here to create a variable with a very "unlikely" name, i.e. one which likely doesn't exist yet in the main package.

Announcements     PerlGuru Announcements Perl Programming Help     Frequently Asked Questions     Beginner     Intermediate     Advanced     Regular Expressions     mod_perl     DBI     Win32 Programming Help Fun With Perl     Perl Quizzes - Learn Perl the Fun Way     Perl Golf     Perl Poetry Need a Custom or Prewritten Perl Program?     I need a program that...     I Need a Programmer for Freelance Work     Throw Down The Gauntlet General Discussions     General Questions     Feedback     Tutorial/Article Suggestions for The Learning Cent     Internet Security Other Programming Languages     Javascript     PHP

Search this forum this category all forums for All words Any words Whole Phrase (options)

Powered by Gossamer Forum v.1.2.0

Web Applications & Managed Hosting Powered by Gossamer Threads
Visit our Mailing List Archives