Contributed by turumkhan
on Jul 27, 2001 at 19:52 UTC
Q&A
> debugging
Description: I know only one way of commenting in perl, and that is # ...
but that only creates a single-line comment. What if i want to comment out a block of code?
Are there any other ways to create comments?
Answer: Better ways to make multi-line comments in Perl? contributed by arhuman A good way is to use the POD system:
=pod
die "testing";
=cut
=for comment
die "testing";
=cut
Also note - any decent code editor should enable you to throw a # in front of a selected set of lines very easily.
| Answer: Better ways to make multi-line comments in Perl? contributed by rob_au I would add to this thread an interesting module which I found recently on CPAN, Acme::Comment - This source filter module allows for comments of many different styles to be incorporated into your code, including multi-line C++ style comments. For example:
use Acme::Comment type => 'C++';
/*
This is a comment ...
... C++ style!
*/
Other commenting styles available through this module include - Fortran, HTML, LaTeX, Lisp and Pascal. | Answer: Better ways to make multi-line comments in Perl? contributed by Abigail-II The problem with just using a here document is
that it will issue a warning under '-w'.
It's much better to use the little known
<< >> operator.
<<q=~q>>;
This is a multiline comment.
q
Abigail | Answer: Better ways to make multi-line comments in Perl? contributed by Anonymous Monk Here's another style, that uses the C preprocessor:
#! /usr/bin/env perl -P
#if 0
this is a
multi-line
comment
#endif
| Answer: Better ways to make multi-line comments in Perl? contributed by Anonymous Monk q^
In case you
were wondering,
this is a multi-line
comment.
^ if 0;
| Answer: Better ways to make multi-line comments in Perl? contributed by roux.tophe A "not-really-comment" that may be used also as a usage message...
my $comment= <<END_COMMENT
this is how my script works
and this is why it doesn't work
blah blah
END_COMMENT
; # don't forget the final ";"
... then usage function may print the $comment variable
| Answer: Better ways to make multi-line comments in Perl? contributed by kcott
There's a variety of ways to add comments using POD.
Quick and dirty method to comment out some code:
=pod
... lines to comment out ...
... should be indented ...
=cut
Adding a single line comment:
=for comment Some single comment line
=cut
...
=for comment
Some single comment line
=cut
Adding a multiline comment:
=for comment Some comment
with multiple
lines.
=cut
...
=for comment
Some comment
with multiple
lines.
=cut
Adding a multiblock coment:
=for comment
lines from
first block
lines from
next block
...
lines from
last block
=cut
| Answer: Better ways to make multi-line comments in Perl? contributed by bharatt Was having a bit of concern due to multi-line comment feature not readily available in perl.
Started to look-out for options and came across this post, and subsequently came to know the various ways we implement the multi-line comment.
Just took one of the options and slightly modified it and have been using it in way like a "defacto" standard in my scripts.
It was nice when i started to use it, and thought would share it.
--- multi-line comment syntax ---
q##//q#
... comments ...
... comments ...
#;
--- example ---
q# -- GLOBAL VARIABLES -- #//q#
----------------
$ps : holds the "ps" command binary
$ps_opt : this extracts only "pid" and
"command name" from the "ps"
output
$ps_opt1 : extracts "command name" along
with its "arguments" for a
given "pid"
$dir : hold "/proc" as value.
This is the source directory
from where the search for
required informations for each
pid starts
$total_swap : stores the sum of swap usage of
all the individual threads/processes
@proc_swap : this array holds the "ref_arrays"
in each of its index
$PROC : is the file/command handle which
holds the information of all the
contents within "/proc" directory
#;
-------------------
Thanks | Answer: Better ways to make multi-line comments in Perl? contributed by bharatt Other applicable form :
q# comment_heading # //
q#
... comment ...
... comment ...
#;
"comment heading" -> is optional
space between "#" and "//" -> is optional
| Answer: Better ways to make multi-line comments in Perl? contributed by bharatt one more way :
' comment heading ' //
'
... comment ...
... comment ...
';
This will be bit more standardized as we might feel like using other characters instead of "#" along with "q" as shown above.
Single quote (') will help in maintaining uniformity while implementing multi-line comments.
| Answer: Better ways to make multi-line comments in Perl? contributed by bharatt a very simple way :
''//'
... comments ...
... comments ...
';
|
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