Re: Ideas on the future of Quesa - Thanks to Dair

[Jose' C. <cru...@ce...>]

Il giorno 29/nov/04, alle 19:53, James W. Walker ha scritto:

> Peter Michelsen <Pet...@mi...> wrote:
>
>> But as a straw pole are we in favor of a real C++ implementation 
>> using inheritance, virtual methods but with no exceptions to replace 
>> the current C based E3 files. Yes or No.
>
> If I had to say just Yes or No on that, I guess I'd have to say No. I 
> think it might be better to use exceptions (and constructors and 
> destructors) than to use inheritance and virtual methods.  As I said 
> in another message, you can't really use STL without using exceptions 
> to some degree.
>
> I'd like to hear more about how you envision using inheritance and 
> virtual methods.  It's not clear to me how we could use inheritance 
> for the Quesa object hierarchy without losing the ability to extend it 
> with plugins, but maybe that's not what you had in mind.
> -- 

Given that the external API doesn't change...

I've to second James on this, and my proposal is:

+ C++,
	I think averybody agree
+ few STL and few exceptions,
	containers, iterators and functors when it makes sense, not to 
templatize everyting,
	exceptions inside Quesa
+ inheritance
	yes the class hierarchy is best described by inheritance, BUT no 
virtuals functions to implement the API, instead I'll make an array of 
function pointers in the class with a slot for every kind of api 
function ( a shortcut to the metahandler) and a hashtable  to plugin 
methods

so
instance.tablePtr = &class.functionArray[];
instance.hashtablePtr = &class.hashtable;

the functionArray is initialized by the class constructor, so it's 
overriden while the class object is constructed

creating the virtual methods with a custom method table, allows the 
creation with plug-ins via the plug-in metahandler

this way allows us also a mild transition. create the C++ base classes 
and derive the others via the metahandler, when things works, begin 
changing the implementation of derived classes in C++.


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