Re: [Webtek-devel] Session methods

[max d. <pro...@gm...>]

hmm.... yes, you are right, this is really tricky. i also spent one  
hour on this problem, and now i understand, there is no clean  
solution, because:

	* the session is loaded explizit via the loader, and all Modules in  
the app-dir via WebTek::Module->load
	* the session is a model
		- a model use the init mehtod to analyze the table and set its  
properties
	* the session has the init method which inits the session (read  
request->cookie, and so on...)
		- there is a clash with the model->init method
		- so there is a hack, and this is to rename the model->init mehod to  
init_model ( i have fixed this now, but its not already checked in )
	* if you want to subclass a model, the subclass is automatically some  
thing like a 'single-table-inheritance', which additionally has some  
other magic to work
		-> so you can not simply subclass a model (as in traditionally OO  
programming)

	=> but there is a solution (because we live in perl ;) ... dirty, but  
a common perl way ;)

so in the file Model/Session.pm say:

	my $session_init = *WebTek::Session::init{'CODE'};

	*WebTek::Session::init = sub {
	   my $class = shift;

	   #... do something here
            log_info('foofoo');
            #... call the super mehtod
	   $class->$session_init();
	}

so what is this:
	* first we copy the coderef into a variable
	* then we create a anonymous subroutine with the new session-init code
		-> it has to be a anonymous subroutine to dont overwrite the  
original init method of WebTek::Session, something like:
				package WebTek::Session; sub init { ... }
			will overwrite the original init mehtod
	* this new coderef will now be called via WebTek::Session->init
		-> and within this we can call the SUPER mehtod
	* tricky isnt it ;)
		-> and this is the common way in javascript to subclass classes  
(ups... sorry instances, or still classes, who will know this in  
javascript, mr. crockford maybe?? ;)
	* simply you can use Hook::LexWrap to simplify things

hmm... i see there is a problem with webtek and OO thinking. i never  
run into such pitfalls, because i more think the webtek way (in rails  
they say, you have to think the rails way, otherwhise you get a lot of  
troubles)

the early releases was really stricktly OO, and more than that, you  
could use every webtek module in your app dir as a stand alone module,  
but this is no longer possible, because i added so much magic, which  
will simplyfy things if you know the magic, but webtek gets much more  
complex with this.. hmmm...

i think it is the time to meet you and make a refactoring of some  
parts, to dont run into such pitfalls (i remember this is not your  
first one, sorry for that...).

max.

On Sep 4, 2008, at 5:48 PM, Adrian Smith wrote:

> I thought it would be nice to be able to define my own methods on  
> the Session class. In other frameworks, it's possible to subclass  
> the Session class, add extra attributes (not necessary in the case  
> of WebTek) and add extra methods.
>
> I thought it might be nice if this happened automatically. So I  
> added code in the Session class to check for the existance of an  
> AppName::Session. If it's there, it's used, otherwise the standard  
> WebTek::Session is used.
>
> However, i didn't get on very well. Firstly the AppName::Session is  
> not automatically loaded (AppName::Classname is not loaded;  
> AppName::Package::Classname is, which I didn't expect), and then I  
> had a problem where the compiler went into an infinite loop when I  
> tried to automatically load the class from somewhere else (I've no  
> idea why) and so I gave up on automatic loading and put "use  
> AppName::Session" in the Handler.pm. The module is loaded, but now I  
> get the error:
>
> You have an error in your SQL syntax; check the manual that  
> corresponds to your MySQL server version for the right syntax to use  
> near '' at line 1' in  delete from session where
>
> I.e. it tries to execute the statement "delete from session where"  
> with no where condition, as far as I can see.
>
> Well, I shall continue trying tomorrow. Currently I have spent about  
> 2 hours on this feature. It is just to display a different text if a  
> certain condition is true, if certain attributes are set on the  
> session at the same time, i.e. all I need is one utility method  
> actually! Maybe I can give up on this approach if it is not  
> possible, and e.g. put the utility method somewhere else e.g. global  
> function somewhere.
>
> Do you have any advice on this matter?
>
> Thanks, Adrian
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