Hello,
في ث، 08-03-2011 عند 17:57 +0100 ، كتب Jan Spurny:
> Hi Frederik,
>
> 'out string' will not work - that was the first thing I tried - problem is
> that if I would have used 'out string' in 'setup' function, the generated C
> code will pass some temporary variable to 'setup' and not the location of the
> required location. That is the reason why I've included that long explanation
> how it works. Maybe I was not clear enough, so let me explain again:
>
> 1) 'setup' functions takes 'location' of 'char*' destionation variable and
> stores it along with 'name' in 'SomeParser' structure
> 2) 'run' then does the parsing and fills all locations described by their
> names by previous 'setup' calls
> 3) now all destionations registered with 'setup' are filled
I see two solutions here: either you use ref (even if it wasn't really
supposed to be used like this, it assumes the reference is valid), or
you use pointers. I feel pointers are the right thing to do here, but
you should take care with memory management. I'd use:
public void setup(string name, string** location);
and then you use it:
string a = null;
x.setup("variable_a", &a);
Using ref would probably work as well, but I prefer pointers as that
will make it clear to the user of the API that there is something
unusual here.
> Another thing - I know that 'char *' is 'string', but why 'string a_str = a;'
> does not work?
You shouldn't know that ;-) Although they map to the same thing in C,
they are different things in Vala.
HTH,
Abderrahim
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