Re: GSL containers: was Re: [Help-gsl] Linear least squares, webpages and the next release

[John D Lamb <J.D.Lamb@johndlamb.net>]

On 05/11/15 04:41, Patrick Alken wrote:
> I agree that stuff is very confusing. I also wonder how much of it is
> needed. In my work I've only ever used the double and complex versions
> of gsl_vector/gsl_matrix. Most of the routines in GSL only work with
> double vectors, with a few extended to complex double (linalg,eigen for
> example).
>
> Do we really need gsl_vector's for int/short/uint/long/etc?

I have used gsl_vector_long on occasion.

> On 11/04/2015 06:43 PM, Gerard Jungman wrote:
>> On 11/04/2015 04:16 PM, Patrick Alken wrote:
>>> I think this is a good idea. Would you be able/willing to design a
>>> new gsl_vector_view structure? Even something very preliminary which
>>> we could iterate a bit to get it to a nice mature status. I, or
>>> someone else, could then run with it and begin the tedious work of
>>> converting all the existing interfaces.
>>>
>>> Patrick
>>
>> If anybody can think of a better way to do the generalizations,
>> besides the current preprocessor implementation, that would be
>> great. I have nothing against the preprocessor, but the current
>> framework makes it nearly impossible to actually read the code.

Ruby? Python? In the absence of C++ templates I usually use one or 
other. Python is likely more readable to C programmers.

>> The current impl is like traits classes, but where the traits
>> are all defined in a very rudimentary way in "templates_on.h".
>> It is impossible to tell what traits are available, which ones
>> are required, and how the separate traits are associated with
>> the basic types at the point where the macros are invoked.

I’m happy to help if someone can suggest a basic workable design. I can 
certainly change the alloc functions to use a pool allocator internally. 
And, since I mostly use C++, I can see the logic of initialising vector 
structs. But I can’t think of a good design that won’t break a lot of 
user code. One of the features of the GSL is that you can’t alloc a 
vector of size 0 without writing a custom allocator. It would be easy to 
change gsl_vector_alloc. But I can’t even think how to do that and 
guarantee not to break user code.

-- 
John D Lamb