[Cython] Utility Codes and templates

[Stefan Behnel]

Vitja Makarov, 25.07.2011 10:25:
> 2011/7/25 Stefan Behnel<stefan_ml at behnel.de>:
>> Vitja Makarov, 25.07.2011 08:41:
>>>
>>> 2011/7/23 Robert Bradshaw<robertwb at math.washington.edu>:
>>>>
>>>> On Fri, Jul 22, 2011 at 3:12 AM, mark florisson
>>>> <markflorisson88 at gmail.com>    wrote:
>>>>>
>>>>> For my work on the _memview branch (and also on fused types) I noticed
>>>>> that UtilityCodes started weighing heavily on me in their current
>>>>> form, so I wrote a little loader in the _memview branch:
>>>>>
>>>>>
>>>>> https://github.com/markflorisson88/cython/commit/e13debed2db78680ec0bd8c343433a2b73bd5e64#L2R110
>>>>>
>>>>> The idea is simple: you put your utility codes in Cython/Utility in
>>>>> .pyx, .c, .h files etc, and then load them. It works for both
>>>>> prototypes and implementations, for UtilityCode and CythonUtilityCode:
>>>>
>>>> This sounds like it could be a nice way to organize our UtilityCode
>>>> snippets. So far we haven't really needed any more templating than
>>>> simple substitution, but for what you're doing I can see this being
>>>> quite handy. This may also provide a more flexible way forward for
>>>> supporting multiple backends.
>>>>
>>>>> myutility.c
>>>>>
>>>>> // UtilityProto: MyUtility
>>>>> header code here
>>>>>
>>>>> // UtilityCode: MyUtility
>>>>> implementation code here
>>>>>
>>>>> You can add as many other utilities as you like to the same file. You
>>>>> can then load it using
>>>>>
>>>>>     UtilityCode.load_utility_from_file("myutility.c", "MyUtility")
>>>>
>>>> I agree with you that having multiple related, named snippets in same
>>>> file is worthwhile. What about
>>>>
>>>> ////////////////////// MyUtility.proto ///////////////////////////
>>>>
>>>> and
>>>>
>>>> ############ MyCyUtility ##############
>>>>
>>>> so the chunks are easy to see.
>>>>
>>>
>>> C++ comments looks ugly. May be it's better to have something like this:
>>>
>>> /* UtilityCode:  MyUtility.proto */
>>> and
>>>
>>> # UtilityCode: MyCyUtility
>>>
>>> That's also pretty easy to parse
>>
>> For the parser, it makes no difference. For a human, it does. A big fat
>> marker like "/////////////////////" is hard to miss, whereas a tiny one like
>> "/* ... */" is easily overlooked within a longer piece of code.
>>
>
> Ok, but how many slashes should be there?
>
> I'd prefer something like:
>
> ########## UtilityCode: MyUtility ################
>
> For both C and Cython

I don't think the parser should care, and I don't think we should put much 
thought into this kind of detail, either. I'd suggest making the separator 
lines at most 78 characters long, and putting as many slashes or hashes in 
there as are needed to fill up the lines after writing the text content. 
What's important to the parser is that there's more than one hash/slash at 
start and end, and something parsable in between. The rest is up to those 
who write the file.

Stefan