Calling multi functions in a single statement

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

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Re: Calling multi functions in a single statement by Eliya (Vicar) on Apr 19, 2012 at 12:54 UTC
So will `$logviewer->get_log_records()->XML_file();` just call both the functions The first method is being called on an object instance of type CCI::LogViewer, and once it has returned, the second method will be called on whatever object has been returned by the first method (could be an object of a different type (i.e. I haven't checked what it returns)).	[reply] [d/l]
Re^2: Calling multi functions in a single statement by akagrawal3 (Beadle) on Apr 20, 2012 at 05:06 UTC
That sounds good. But from what you said I believe that there should be more than one `XML_file` subroutine so that once an object is returned by `get_log_records()` it could decide on which Package it should call `XML_file()`. Now if that is true, I found that the subroutine `XML_file` is only in one package and not in any other. So does that make any sense in executing `$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]
Re^3: Calling multi functions in a single statement by JavaFan (Canon) on Apr 20, 2012 at 08:45 UTC
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]
Re^2: Calling multi functions in a single statement by akagrawal3 (Beadle) on Apr 20, 2012 at 05:22 UTC
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
See also references quick reference, https://metacpan.org/module/DROLSKY/perl-5.15.6/pod/perlootut.pod	[reply]


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