Re: [casetta] About compatibility between casio models

[Florian Birée <florian@xxxxxxxxxx>]

Fabien ANDRE a écrit :
> > What do you think about it?
> Errr... What I think about that ? First and foremost I am impressed by 
> this system :-D
>
> Seriously, I think that the model you propose for casetta is the best... 
> for users ! But it may be the worst for developers as it seems quite 
> complicated to implement :-p

And because we are free software developers, we'll choose the best for 
users :)

> About the implementation, I have the beginning of an idea. It would use 
> the new object models of cas.py.
> /I think each get_raw_data_list method (which is called before any 
> transfer) could call another method named is_valid which would take the 
> model of calculator in argument and raise errors. For example for a 
> program :
>
> class TransferableProgram(datacls.Program):
>     ....
>     def is_valid(self, calculator_model):
>        if calculator_model != "G100" and len(self.name):
>           raise TooLongNameError
>        if calculator_model == "G25":
>           for line in self.get_text():
>              raise
>
> class TransferableList(datacls.List):
>     ....
>     def is_valid(self, calculator_model):
>      if calculator_model == "G25":
>        raise ListNotAvailable
>
> An then casetta_cli and gasetta could provide fixes using try: except 
> blocks. Or maybe we should directly include a method to do the various 
> fixes inside the objects. This implementation has advantages : quite 
> easy to implement, ability to make completely different tests for any 
> data_type and drawbacks : the method is_valid may be enormous for some 
> data_types such as programs, it is not really "clean" as the 
> compatibility test suite is not located is a specific module, and we 
> cannot distinguish fatal, major errors and warnings. For warnings maybe 
> just a return -1, "Your picture uses colors, I may not be displayed 
> correctly." is enough.

This is a good idea, but raising exceptions has a problem : is a data 
has more than one problem, only the first found will reported...
I think it could be better to have a strict separation between transfers 
and compatibility check: the casetta python package provides both, and 
it's the interface choice to make a test before a transfer.
I think it would be better if the compatibility system return an object 
like that:

report.has_error #return if we can transfer the file or not
report.has_warning #return if we should display some warnings
for data in my_file:
	report[data].has_error #return if this data has raised an error
	report[data].has_warning #return if the data has raised a warning
	for error in report[data].errors:
		error.summary #informations about the error
		error.can_be_fixed #return if the error can be fixed
		error.is_warning #return if the error is a warning
		error.fix() #return the data fixed

This object should be generated by a module which take:
 * For each data, some test functions
 * For each casio models, some rules to use with previous functions

It's a detail, but an error.summary property will said that we introduce 
some end-user text to translate in casetta (for the moment, all end-user 
messages are in interfaces). Maybe we can make instead an error.id 
property, with constants for each id, and interfaces will use their 
messages for each id...

> About backups, I think they should use the Fx-Interface model, they 
> should be calculator dependent, although it may be possible to transfer 
> a backup of a G35 to a G65. However, we will have huge problems !

The Fx-Interface is to make manage backup in another way than all other 
data. We could simply use a rule to check is the model match the backup 
(it's easy, we know where the model is stored in a backup), isn't it ?

> About the particularities, you are right it is the first thing we should 
> do. Listing the particularities may help us to find a good implementation.
> Where should we publish this information on the wiki ?

Here : http://casetta.tuxfamily.org/formats/models

I'll make the firsts tickets about the compatibility system in 
http://dev.filyb.info/casetta/

Cheers,
--
Thesa ~ Florian Birée
e-mail : florian@xxxxxxxxxx
Messagerie Instantanée Jabber/XMPP/Google Talk : florian.biree@xxxxxxxxx
Site web : http://florian.biree.name/
Carnet web : http://filyb.info/

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