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Full Discussion: perl explain syntax !!!
Top Forums UNIX for Advanced & Expert Users perl explain syntax !!! Post 302315462 by cbkihong on Tuesday 12th of May 2009 11:02:50 AM
Old 05-12-2009
Quote:
Originally Posted by pludi
From the hash 'this', get the value associated with the key 'localtion', and treat it as a reference to a scalar.
This is not really correct.

$this is a hash reference. That is, a reference to a hash. $$this{'location'} dereferences $this to access the value associated with the "location" key.

Another way to write this is $this->{'location'} = 'xxxxxxx';

You may easily confirm this by using Data::Dumper to inspect complex data structure.

Code:
C:\Users\bernardchan>perl -MData::Dumper -e "$$this{'location'}='xxxx'; print Dumper($this)"
$VAR1 = {
          'location' => 'xxxx'
        };

C:\Users\bernardchan>perl -MData::Dumper -e "$this->{'location'}='xxxx'; print Dumper($this)"
$VAR1 = {
          'location' => 'xxxx'
        };

 

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Data::Dumper::Concise(3)				User Contributed Perl Documentation				  Data::Dumper::Concise(3)

NAME
Data::Dumper::Concise - Less indentation and newlines plus sub deparsing SYNOPSIS
use Data::Dumper::Concise; warn Dumper($var); is equivalent to: use Data::Dumper; { local $Data::Dumper::Terse = 1; local $Data::Dumper::Indent = 1; local $Data::Dumper::Useqq = 1; local $Data::Dumper::Deparse = 1; local $Data::Dumper::Quotekeys = 0; local $Data::Dumper::Sortkeys = 1; warn Dumper($var); } So for the structure: { foo => "bar baz", quux => sub { "fleem" } }; Data::Dumper::Concise will give you: { foo => "bar baz", quux => sub { use warnings; use strict 'refs'; 'fleem'; } } instead of the default Data::Dumper output: $VAR1 = { 'quux' => sub { "DUMMY" }, 'foo' => 'bar baz' }; (note the tab indentation, oh joy ...) If you need to get the underlying Dumper object just call "DumperObject". Also try out "DumperF" which takes a "CodeRef" as the first argument to format the output. For example: use Data::Dumper::Concise; warn DumperF { "result: $_[0] result2: $_[1]" } $foo, $bar; Which is the same as: warn 'result: ' . Dumper($foo) . ' result2: ' . Dumper($bar); DESCRIPTION
This module always exports a single function, Dumper, which can be called with an array of values to dump those values. It exists, fundamentally, as a convenient way to reproduce a set of Dumper options that we've found ourselves using across large numbers of applications, primarily for debugging output. The principle guiding theme is "all the concision you can get while still having a useful dump and not doing anything cleverer than setting Data::Dumper options" - it's been pointed out to us that Data::Dump::Streamer can produce shorter output with less lines of code. We know. This is simpler and we've never seen it segfault. But for complex/weird structures, it generally rocks. You should use it as well, when Concise is underkill. We do. Why is deparsing on when the aim is concision? Because you often want to know what subroutine refs you have when debugging and because if you were planning to eval this back in you probably wanted to remove subrefs first and add them back in a custom way anyway. Note that this -does- force using the pure perl Dumper rather than the XS one, but I've never in my life seen Data::Dumper show up in a profile so "who cares?". BUT BUT BUT ... Yes, we know. Consider this module in the ::Tiny spirit and feel free to write a Data::Dumper::Concise::ButWithExtraTwiddlyBits if it makes you happy. Then tell us so we can add it to the see also section. SUGARY SYNTAX
This package also provides: Data::Dumper::Concise::Sugar - provides Dwarn and DwarnS convenience functions Devel::Dwarn - shorter form for Data::Dumper::Concise::Sugar SEE ALSO
We use for some purposes, and dearly love, the following alternatives: Data::Dump - prettiness oriented but not amazingly configurable Data::Dump::Streamer - brilliant. beautiful. insane. extensive. excessive. try it. JSON::XS - no, really. If it's just plain data, JSON is a great option. AUTHOR
mst - Matt S. Trout <mst@shadowcat.co.uk> CONTRIBUTORS
frew - Arthur Axel "fREW" Schmidt <frioux@gmail.com> COPYRIGHT
Copyright (c) 2010 the Data::Dumper::Concise "AUTHOR" and "CONTRIBUTORS" as listed above. LICENSE
This library is free software and may be distributed under the same terms as perl itself. perl v5.18.2 2013-12-31 Data::Dumper::Concise(3)
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