"Method is not in the class but it is there!"

shak380 has asked for the wisdom of the Perl Monks concerning the following question:

The application I currently work on has a class named, CC2::Schema::BirthdayCardList. and there is an object of it which calls a method 'add_to_birthday_cards', but I cant see any so named method or any AUTOLOADs in either the same class or any parent classes of it. So I wonder where this method is located and how it works. I tried to find it with, Class::ISA and the output was as below :

perl -I ~/lib/ -MCC2::Schema::BirthdayCardList -MClass::ISA -le 'for (
+Class::ISA::super_path( "CC2::Schema::BirthdayCardList" )) { print "\
+$_ is : $_"; print "I have the method, add_to_birthday_cards\n" if $_
+->can("add_to_birthday_cards") }'
[download]

and the output was as follows :

$_ is : Local::CMSDBIx
$_ is : DBIx::Class::InflateColumn::DateTime
$_ is : DBIx::Class::InflateColumn
$_ is : DBIx::Class::Row
$_ is : DBIx::Class::Core
$_ is : DBIx::Class::Relationship
$_ is : DBIx::Class::Relationship::Helpers
$_ is : DBIx::Class::Relationship::HasMany
$_ is : DBIx::Class::Relationship::HasOne
$_ is : DBIx::Class::Relationship::BelongsTo
$_ is : DBIx::Class::Relationship::ManyToMany
$_ is : DBIx::Class::Relationship::Accessor
$_ is : DBIx::Class::Relationship::CascadeActions
$_ is : DBIx::Class::Relationship::ProxyMethods
$_ is : DBIx::Class::Relationship::Base
$_ is : DBIx::Class::PK::Auto
$_ is : DBIx::Class::PK
$_ is : DBIx::Class::ResultSourceProxy::Table
$_ is : DBIx::Class::ResultSourceProxy
$_ is : DBIx::Class
$_ is : DBIx::Class::Componentised
$_ is : Class::C3::Componentised
$_ is : Class::Accessor::Grouped
[download]

That is none of them have a so called method. However if I run this :

perl -I ~/lib/ -MCC2::Schema::BirthdayCardList -le 'print "Yes.....\n"
+ if CC2::Schema::BirthdayCardList->can("add_to_birthday_cards")'
[download]

it prints "Yes.....". So what is magical here ?

Comment on "Method is not in the class but it is there!" Select or Download Code

Replies are listed 'Best First'.
Re: "Method is not in the class but it is there!" by chrestomanci (Priest) on Sep 05, 2011 at 09:42 UTC
I see that you have asked the same question on LinkedIn No one here at the monastery will object to you seeking opinions elsewhere. We are not perfect and for some questions there are likely to be wise persons on other forums with better answers, but when you do ask a question in multiple places it is courteous to say so, and to provide links, so that we can see what others have said in those other forums, so that we may learn from them, and avoid repeating the same answer.	[reply]
Re^2: "Method is not in the class but it is there!" by shak380 (Novice) on Sep 05, 2011 at 11:30 UTC
Yes, I understand. I was waiting for a correct answer and I have done it! so no worries!	[reply]
Re: "Method is not in the class but it is there!" by Anonymous Monk on Sep 05, 2011 at 07:19 UTC
Probably nothing `use Data::Dump::Streamer; print Dump( CC2::Schema::BirthdayCardList->can("add_to_birthday_cards") );` [download]	[reply] [d/l]
Re^2: "Method is not in the class but it is there!" by shak380 (Novice) on Sep 05, 2011 at 08:36 UTC
I believe there is something, otherwise how does the code work ? btw, I executed your code and it didn't produce anything. Anymore ideas from anyone ?	[reply]
Re^3: "Method is not in the class but it is there!" by Anonymous Monk on Sep 05, 2011 at 08:40 UTC
That is not possible :) it should produce something `use Data::Dump::Streamer; print Dump( Data::Dump::Streamer->can('VERSION') ); __END__ $CODE1 = \&UNIVERSAL::VERSION;` [download]	[reply] [d/l]
Re^4: "Method is not in the class but it is there!" by shak380 (Novice) on Sep 05, 2011 at 08:55 UTC
Re^5: "Method is not in the class but it is there!" by kcott (Archbishop) on Sep 05, 2011 at 11:19 UTC
Some notes below your chosen depth have not been shown here
Re^5: "Method is not in the class but it is there!" by Anonymous Monk on Sep 05, 2011 at 09:32 UTC
Re^5: "Method is not in the class but it is there!" by Anonymous Monk on Sep 05, 2011 at 09:34 UTC
Re: "Method is not in the class but it is there!" by JavaFan (Canon) on Sep 05, 2011 at 08:15 UTC
Do note, as the output shows, that `Class::ISA::super_path` does not return the package it's called with (unless there's a loop in the inheritance structure). So, if `&CC2::Schema::BirthdayCardList::add_to_birthday_cards` exists, you get the behaviour you are seeing. Alternatively, someone has put it in `UNIVERSAL`, which also isn't returned by `super_path`.	[reply] [d/l] [select]
Re^2: "Method is not in the class but it is there!" by shak380 (Novice) on Sep 05, 2011 at 08:45 UTC
>> "if &CC2::Schema::BirthdayCardList::add_to_birthday_cards exists, you get the behaviour you are seeing" Yes, that is obvious, but as I mentioned there is no such method or a single word 'add_to_birthday_cards' in the module, CC2::Schema::BirthdayCardList. Also, it is not in UNIVERSAL, please see this : `perl -I ~/cc-tmpl/lib/ -MUNIVERSAL -le 'print "Yes.....\n" if UNIVERSA +L->can("add_to_birthday_cards")'` [download] doesn't print "Yes.....". Also, `grep 'add_to_birthday_cards' /usr/lib/perl5/5.8.8/UNIVERSAL.pm -rli` [download] outputs nothing.	[reply] [d/l] [select]
Re^3: "Method is not in the class but it is there!" by moritz (Cardinal) on Sep 05, 2011 at 10:22 UTC
Note that Perl supports creation of methods with dynamic names at run time and compile time, so a grep not showing a result suggest that this might be the case. Perl 6 - second systems done right	[reply]
Re^3: "Method is not in the class but it is there!" by JavaFan (Canon) on Sep 05, 2011 at 10:38 UTC
If you can't find it at all, and if the method uses variables, pass in a tied variable that dumps a stack trace on a FETCH. That should give you some line numbers to work with (or an indication the method was evalled into existence).	[reply]
Re^3: "Method is not in the class but it is there!" by Anonymous Monk on Sep 05, 2011 at 09:25 UTC
Um, UNIVERSAL.pm is a core module, nobody edits UNIVERSAL.pm, but modules/programs, might at runtime, despite it being a bad practice, add symbols to UNIVERSAL namespace	[reply]
Re: "Method is not in the class but it is there!" by moritz (Cardinal) on Sep 05, 2011 at 10:13 UTC
Maybe some of the classes defines its own `can` method? What happens if you just call the method? Perl 6 - second systems done right	[reply] [d/l]
Re: "Method is not in the class but it is there!" by shak380 (Novice) on Sep 05, 2011 at 10:24 UTC
Hi guys, Thank you all for your valuable suggestions and helping me out. Anyway, I have got a seemingly right answer from linkedin(Perl group). I will confirm it and will post the result later. Anyways, here is the link : <link>http://www.linkedin.com/groupItem?view=&gid=106254&type=member&item=69158748&qid=d1a40232-965a-4706-88f1-6e43e50a965a&trk=group_most_popular-0-b-ttl&goback=%2Egde_106254_member_69158748%2Egmp_106254</link>	[reply]
Re^2: "Method is not in the class but it is there!" by moritz (Cardinal) on Sep 05, 2011 at 12:53 UTC
For those not on linkedin, the answer seems to be that DBIx::Class automatically generates `add_to_$relationship` methods for has_many and many_to_many relationships. See DBIx::Class::Relationship::Base. Perl 6 - second systems done right	[reply] [d/l]
Re^2: "Method is not in the class but it is there!" by shak380 (Novice) on Sep 05, 2011 at 11:27 UTC
Yes, that answer is correct indeed! I have tested and confirmed it.	[reply]
Re^3: "Method is not in the class but it is there!" by Anonymous Monk on Sep 05, 2011 at 11:56 UTC
Well, what is it?	[reply]
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