[Pyrex] "Language Overview" confusion

[David Goldsmith]

So the sentence:

"It's important to understand that Pyrex does /not/ itself read the C 
header file, so you still need to provide Pyrex versions of any 
declarations from it that you use"

is *not* describing something you "still" have to do after you've done 
the declarations example-d above it, but rather *explaining why* you 
have to provide those declarations?  In other words, if the example 
declaration is an example of a "Pyrex version of [a] declaration," then 
the "...Pyrex does /not/ itself read the C header file, so you still 
need to provide..." portion of the sentence is confusing.

DG

Bob Van Zant wrote:
> On 6/5/07 2:41 PM, "David Goldsmith" <David.L.Goldsmith at noaa.gov> wrote:
>
>   
>> As a newbie, I have no idea what the second part of this sentence means:
>> "provide Pyrex versions of any declarations" - where (i.e., in which
>> file)?  What do these look like?
>>
>> (By implication, the previous example:
>>
>>     cdef extern from "spam.h":
>>
>>         int spam_counter
>>
>>         void order_spam(int tons)
>>
>> (which goes in the .pyx file, yes?) is *not* such a declaration, but no
>> positive example of such a declaration appears to be given, at least not
>> at that place in the LO, and it is not clear in which file said
>> declaration should go).
>>     
>
> Those actually are the declarations. The "cdef extern from..." will
> eventually turn into a #include line. The rest of the declarations tell
> Pyrex about the variables, functions and types you'll be using.
>
> These can go directly in the .pyx file. For instance, to get strlen you
> could put this into your .pyx file:
>
> cdef extern from "string.h":
>     size_t strlen(char *s)
>
> You can then just call strlen() from within your pyrex. If you have more
> than a few of these declarations you can put them into a separate file with
> extension .pxi and then include that from your .pyx file.
>
> -Bob
>
>   

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