[gecode-users] Gecode/FlatZinc 1.1 released

[Guido Tack]

Raffaele Cipriano wrote:

> Dear Guido,
> I'have installed the "Flatzinc for Gecode 1.1" release, and it works.
> But perhaps I  misunderstood something... I thought that the parser  
> would have returned a
> gecode space in a c++ file

No, Gecode/FlatZinc is an interpreter for FlatZinc, not a compiler.   
The advantage is that no additional step of compilation is needed -  
the user does not have to have a C++ compiler installed.

> , for example I thought that executing
>
> $ fz myInstanceOfGolombRulers.fzn
>
> should have create a myInstanceOfGolombRulers.cc file
>
> to be compiled and executed...but it doesn't seem to work in this  
> way...
>
> Is the gecode space only an internal translation?
> Is it directly executed by the fz command?

Yes, the fz command creates a new space, parses the input and creates  
all variables and propagators, and then calls one of the search  
engines.  If you need more direct access to the space that results  
from parsing, you can use Gecode/FlatZinc as a library.  Have a look  
at the file main.cc.  The two lines
   FZPrinter p;
   FlatZincGecode* fg = FlatZinc::solve(contents, p);
Parse the string contents into a gecode space fg (FlatZincGecode  
inherits from Gecoode::Space).

If you need a compiler that generates C++ from FlatZinc, you may want  
to look at the new reflection capabilities (introduced in Gecode  
2.0.0).  They would let you take the FlatZincGecode object, iterate  
over all its propagators and variables, and generate C++ code that  
recreates an equivalent space.

Cheers,
	Guido