[Lazarus] Request for student project ideas

[Hans-Peter Diettrich]

Paulo Costa schrieb:

> An interesting idea, but probably too hard for a student project, would 
> be the capability of using a C library without having to manually create 
> the pas file that translates the c header.

This is what ToPas can already do. But...

> That is tedious, error prone 
> and a mess when the .h changes and we continue to use the wrong .pas and 
> strange error creep in.

Right, the translator needs exactly the header files as used to create 
the library.

I'm aware of possible changes in C libraries and header files, and 
that's why now I suggest an Pascal compiler with the added ability to 
process C files. Then that compiler would both compile a changed 
library, and create an Pascal interface unit at the same time. This is 
exactly what the CBuilder does for Delphi.

A transformation of C files into Pascal units, as ToPas can do (to some 
degree), IMO is only a provisional solution. When manual intervention is 
required in this step, it will be required for every following bugfix or 
improvement to the C code.

> Also there are a lot of C libraries that are not available to fpc 
> because nobody had the time to create the bindings. I know that there is 
> h2pas but it is a off line tool and needs a lot of help from the 
> programmer.
> 
> A better way could be to hack a C compiler (GCC ?) and use only the 
> parser and the first compilation stage to have the symbols related to 
> the available functions and structures

This part of ToPas is already finished :-)

> and create the pas header from 
> that information. With such tool we could have almost automatic use of 
> any c library...

The hardest problem I found in ToPas is an automated handling of the 
#defines. They should be classified into literal constants, functions, 
macros, and (incomplete) code snippets - where code snippets IMO are of 
no use in a Pascal unit. Such classification could be done easily by an 
LR parser, but an LL parser only can deal with complete source files.

DoDi