Re: Accessing table methods via C++

[luigi@...]

Works great.  The 'self' parameter is excellent and the code now makes
sense.

Thanks for the help!


Luigi Rosso
Lead Developer
RealitySlip
http://www.RealitySlip.com


----- Original Message -----
From: "Michael Flad" <Michael.Flad@fantastic-realms.com>
To: "Multiple recipients of list" <lua-l@tecgraf.puc-rio.br>
Sent: Friday, March 07, 2003 11:43 AM
Subject: RE: Accessing table methods via C++


> Hi,
>
> you define the function using the "method form", by using a : between
> the table and function name so there's an additional hidden first
> parameter named "self" (like the this pointer in C++).
>
> You have to push your table as first paramter onto the stack or
> if you don't need instance related information, just create the
> function with a "." like
>
> function myTable.saysomething( a, b )
>
> Regards,
>
>   Michael Flad
>
> --
> Fantastic Realms Interactive GmbH - Germany
> Phone: +49 (0)7121 / 983 7820
> Fax:   +49 (0)7121 / 983 7830
>
>
> > -----Original Message-----
> > From: owner-lua-l@tecgraf.puc-rio.br
> > [mailto:owner-lua-l@tecgraf.puc-rio.br]On Behalf Of
> > luigi@realityslip.com
> > Sent: Friday, March 07, 2003 10:38
> > To: Multiple recipients of list
> > Subject: Accessing table methods via C++
> >
> >
> > Hello,
> >
> > I'm trying to access call a table's method from C++ by manipulating the
> > stack.  Seems fairly straightforward after reading the manual, in fact
it
> > works fine but I oddly need to push an extra parameter for the function.
> > I'm probably not manipulating the stack properly and I was hoping
someone
> > could spot what's wrong.
> >
> > Here's an example:
> >
> > [LUA CODE]
> >
> > myTable = {}
> > function myTable:saysomething( a, b )
> >     print( "myTable says: " .. a .. " " ..  b )
> > end
> >
> > [C CODE]
> > // luaVM is an open lua_State
> > lua_getglobal(luaVM, "myTable");
> > lua_pushstring(luaVM, "saysomething");
> > lua_gettable(luaVM, -2);
> >
> > lua_pushstring(luaVM, "param UNKNOWN!!");
> > lua_pushstring(luaVM, "param a");
> > lua_pushstring(luaVM, "param b");
> > lua_call(luaVM, 3, 0);
> >
> > [LUA OUTPUT]
> >
> > myTable says: param a param b
> >
> > Theoretically I should only push two string parameters and call lua_call
> > with 2 instead of 3 as nargs.  Yet by doing so I get an error: "attempt
to
> > concat local value 'b' (a nil value)" which seems to indicate
> > that I've only
> > passed one parameter to the function.  As it is, I have no idea
> > what happens
> > to the unknown (first parameter) I push on the stack and it
> > doesn't seem to
> > be affecting execution in any way.  I'm confident it's a mistake with my
> > table method calling as it works fine with normal global functions.
> >
> > Thanks for reading :-)
> >
> > Luigi Rosso
> > Lead Developer
> > RealitySlip
> > http://www.RealitySlip.com
> >
>
>
>
>