Re: List: forEach: arg1;

[Kevin Crowston]

"Ludo Pagie" <address@hidden> wrote:

>-addConcentration: (double) c;

>[metabList forEach: M(addConcentration:) : myarg];
>with:
>
>>reaction.m: In function `_i_Reaction__react_':
>>reaction.m:38: incompatible type for argument 4 of indirect function call

It helps to know that a message send is basically syntactic sugar for a
function call--the line above is (more or less) turned into the function
call:

_i_Reaction__react_(metabList, sel, M(addConcentration), myarg)

So argument four is myarg.

>without this line the program compiles (and runs) fine. I guess that the
>argument 4 is an argument of one of those (?) run-time function-calls (eg.
>"objc_msgSend" in Next Objective C, don't know about Swarms run-time system).

The incompatible type comes because the forEach:: expects to get id's as
arguments, and you're passing a double.  I had similar problems in my
simulation.  What I ended up doing was: (1) switching to float's, since
they're the same size as id's, at least on a Sun--you might want to verify
this on whatever you're using.  (2) passing the float as an id--this was a
bit ugly, since it turns out you can't simply cast a float to a pointer.
What I ended up doing was taking a pointer to my float, casting it to a
pointer to an id, and deferencing the pointer... ugly at best.  If I
remember correctly, it looked like:

           (*((id*)(&f)))

There's probably a more elegant way, but I think this worked.

Kevin