Re: [ANN] an EBNF parser and coding pattern tool (LGPL)

[Brian Inglis <Brian.Inglis@SystematicSw.ab.ca>]

On 12 Feb 2003 01:30:42 GMT in comp.lang.c.moderated, Hyman Rosen
<hyrosen@mail.com> wrote:

>Cedric LEMAIRE wrote:
>> The C++ compiler doesn't give you introspection to implement C++
>> templates that work on the composition of a class.
>
>Yes, this is true. To get this would require support from the
>compiler, and I imagine would look something like this - the
>result of introspect<T> for some type T would be a class with
>informative members, some of which would be like Alexandrescu's
>type lists that would carry member and base class information
>and could be processed recursively by other templates. We would
>also want an equivalent dynamic interface, so that we could take
>a polymorphic pointer or reference and deal with its introspection
>at runtime.

Macros have been used in C for years to generate generic
structures and code to process them. Define all the structure
member names and types as macro arguments calling a macro that is
a parameter of the structure definition macro, with a few extra
parameters in each level of macro for code gen arguments, e.g.

#define OBJ(B,M,E,X,Y,Z)\
B\
M(int,i,X,Y,Z)\
M(char,c,X,Y,Z)\
E

#define TD typedef struct s {
#define ETD } s
#define TN(t,n,X,Y,Z) t n;
#define O(t,n,X,Y,Z) << n

OBJ( TD, TN, ETD, , , );

OBJ( cout, O, , , , );

Extend as required. 

Thanks. Take care, Brian Inglis 	Calgary, Alberta, Canada
-- 
Brian.Inglis@CSi.com 	(Brian dot Inglis at SystematicSw dot ab dot ca)
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