akagrawal3 has asked for the wisdom of the Perl Monks concerning the following question:

Greetings Monks, I have a little difficulty in understanding one statement in which two functions called. 
139     my $logviewer = CCI::LogViewer->new(
140         {   request         => $request,
141             start_timestamp => $start_date,
142             end_timestamp   => $end_date,
143             filter_string   => $filter,
144             lgp_object      => 'shortMessage',
145             lgp_subtype     => 'eventEndPoints',
146             limit           => $limit,
147             sid             => $request->get_args()->{'sid'},
148         }
149     );
150     $logviewer->get_log_records()->XML_file();

[download]
The statement my $logviewer = CCI::LogViewer->new( creates an object in user-defined package LogViewer.pm which is in CCI folder. This package has several functions of which get_log_records and XML_file are two of them. Now after the execution of first statement my $logviewer will be pointing to LogViewer.pm package. So will $logviewer->get_log_records()->XML_file(); just call both the functions or is there any other scenario I am failing to understand. Your help in this regard will be highly appreciated. Thanks

Replies are listed 'Best First'.
Re: Calling multi functions in a single statement
by Eliya (Vicar) on Apr 19, 2012 at 12:54 UTC
    So will $logviewer->get_log_records()->XML_file(); just call both the functions

    The first method is being called on an object instance of type CCI::LogViewer, and once it has returned, the second method will be called on whatever object has been returned by the first method (could be an object of a different type (i.e. I haven't checked what it returns)).

[reply]
[d/l]
      That sounds good. But from what you said I believe that there should be more than one XML_file subroutine so that once an object is returned by get_log_records() it could decide on which Package it should call XML_file(). Now if that is true, I found that the subroutine XML_file is only in one package and not in any other. So does that make any sense in executing  $logviewer->get_log_records()->XML_file();. It could have rather just been written as 
      $logviewer->get_log_records();
$logviewer->XML_file();

      [download]
[reply]
[d/l]
[select]
        Just because XML_file is in the same class as get_log_records doesn't mean the two statements are equivalent. Perhaps they are. But that depends on what get_log_records returns. And it only depends on what get_log_records returns.
[reply]
Re: Calling multi functions in a single statement
by JavaFan (Canon) on Apr 19, 2012 at 13:04 UTC
    So will $logviewer->get_log_records()->XML_file(); just call both the functions or is there any other scenario I am failing to understand.
    Perl calls get_log_records on $logviewer, and it calls XML_file on whatever object is returned by get_log_records. This maybe the same object as $logviewer, but without inspecting what get_log_records does, is something that cannot be answered. It's very well possible methods in different classes are being called.
[reply]
[d/l]
[select]
      Thanks for your response. Could you please take some effort in answering my query which I posted in

      http://perlmonks.org/?node_id=966076

[reply]
Re: Calling multi functions in a single statement
by Anonymous Monk on Apr 19, 2012 at 12:58 UTC
[reply]

Back to Seekers of Perl Wisdom