On Jun 24, 2008, at 4:45 PM, Satish Balay wrote:

On Tue, 24 Jun 2008, Barry Smith wrote:

...

Absolutely NOT!

It is perfectly reasonable to have the const in user code; WHENEVER a user uses a static string they should/must make it const

Expecting users to use 'const char*' is "perfectly reasonable" - but expecting users to use 'const VecType' (which is a predefied type) is a step below it. [esp when we don't have const Mat, const Vec etc...].

So the above expectation assumes the user knows the internal impl of this type is 'char *' - etc.. - and its not 'const *' due to these implemenation issues etc..

So I think the current expectation is a minor deviation - and what I propose is also a minor hack.. [with a benifit of more consistant user code]. So whatever option we choose - we do it by accepting the limitation of that choice.

I guess part of the design issue is: we have a requirement for 'VecType' functionality.

Initially we choose 'enum' for this. This choice had limitations [could not add new types].

Yupp

Then we choose "char *"

Yupp,

which evolved into "const char*" due to compiler issues.

Actually I consider that I added the const to make the compiler happy without really understanding what I was doing with const (I still don't completely understand const). I consider now my "fix" at that time was wrong (adding the const to VecType etc) and I should have properly prototyped each function, like I have just tried to change things to do. Somehow Matt and Lisandro seem to think my "fix" of adding const to VecType (and XXType) was fundamentally correct; I think it was just a result of my stupidity.

But now we have new issues with the 'const' side of things - limiting the extensibility of 'VecType'. [cannot dynamically construct a string and assign is as a new type]

Perhaps we should get away from strings [and its implemetation consequences] - and look for a better way to abstact out the impl details from the interface requirements. [I don't have any proposal along these lines - so the above is just noisy thoughts with no value..]

We can easily eliminate the XXType completely and just have XXXSetType(XXX,const char *) then one could do const char *vtype = VECMPI; instead of const VecType vtype = VECMPI; Perhaps this is best, I introduced XXXType just to make the code more transparent, not to have some kind of magic correctness checking. If it is not making the code more transparent, we might as well toss it. Barry

Satish