Hi Udo,
Udo Schroeter schreef op 16/09/2014 12:12:
Again, it's helpful to look at the Lua source
itself, for example the liolib.c which I mentioned
earlier.
Yes yes, I have done this a lot before and solved other problems
that way, but I can't find this one.
The steps involved would be:
1) create the userdata object
2) make a new table and set it as the metatable for the
object
^ this gives you a C struct linked with a Lua table, you
don't have to do any housekeeping to keep them associated.
3) Now, from the user side, you probably want to make
changing values in that table easier for them. That's where
you could pre-populate the metatable with a __newindex and
an __index function that takes care of storing and
retrieving values - so people can use the idiom you
described with the onMouseMove example.
Yes, I have done these things before a lot, I have created lots of
objects before.
For this, you'd have to make a little C function that
takes the incoming values and saves them to the metatable
itself.
But I think this is the magic answer for my question: I need to
put the value in the metatable itself.
I think that for me, the metatable has always been some kind
of magical object but it is actually just a table associated to
another object that I can put values in. I think I understand now
and I will try it!
Thanks.
4) Using the table from the C side is simple. You retrieve the
metatable for your struct, look up the pertinent function and
call it if present. You can find examples for this throughout
the Lua *lib.c files as well.
And then, yes, of course, it is easy. I just push the user data, get
the meta table, call its onMouseMove function (if it exists).
I hope this helps you get on your way. It takes a little effort
to get acquainted with the Lua API, but once you get the hang of
it, everything should fall into place...
Yes, thanks! I have done a lot of projects in Lua before and I have
never had any problems with it because I always sticked to Lua
objects or C objects and not really interact between them as this
was usually not necessary.
I hope this was my last email about this :-)
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