[py-configparser-devel] CLOS, structs and ABCL?

[Abhishek Reddy]

Hi Erik,

On Sat, Aug 7, 2010 at 6:13 AM, Erik Huelsmann <ehuels at gmail.com> wrote:

> moving to CLOS isn't on the roadmap right now.
>

 That's fine.

Do you feel you have a need for the library to be CLOS based? If so,
> could you explain your use-case?
>

It is not a need, only a wish.  If the original intent to use CLOS was still
there, it would get my support.

I see some potential benefits to using CLOS, largely because it offers an
easy protocol for extending and customizing behaviours:

* I believe the name-transform functions are special cases of what could be
a method combination on the reader of a name slot; and it may also be useful
to denote them separately from the constructor call;

* Generally, being able to plug methods around getters and setters can be
useful for applying additional validation and constraints;

* Customizing object initialization can be similarly useful (e.g. plugging
in an early check for a rule, that may signal a restartable condition);

* Customizing printing (see next point);

* Most importantly, subclassing to group such specific extensions is more
flexible, permitting modular design of client code.

Of course, one can work around structs to achieve the same sort of results,
but I think it may be simpler and easier to do it the CLOS way.

In practice, I have written a validation layer[1] for py-configparser, which
arguably suffers some mismatch where I have wrapped the structs and several
functions.  Such extensions might be integrated more neatly if the basic API
used CLOS.  Generally, when using py-configparser, I find myself writing ad
hoc wrapper functions for specific transformation, validation and printing
behaviours, whereas to subclass and appropriately specialize a generic
function might be a better style.

[1] http://gitorious.org/py-configvalidator

Thanks



>
> Bye,
>
>
> Erik.
>
>
> On Fri, Aug 6, 2010 at 5:44 PM, Abhishek Reddy <arbscht at gmail.com> wrote:
> > Hi,
> >
> > A comment in config.lisp suggests that structs are used instead of CLOS
> due
> > to an issue with ABCL as of 2008.  Has the situation with ABCL improved,
> > given its substantial development since then?  If so, would it make sense
> to
> > abandon structs for CLOS in py-configparser?
> >
> > --
> > Abhishek Reddy
> > http://abhishek.geek.nz
> >
> >
> > _______________________________________________
> > py-configparser-devel mailing list
> > py-configparser-devel at common-lisp.net
> > http://common-lisp.net/cgi-bin/mailman/listinfo/py-configparser-devel
> >
> >
>



-- 
Abhishek Reddy
http://abhishek.geek.nz
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