RE: 1 problem & 2 q's
> -----Original Message-----
> From: gherson at snet.net [mailto:gherson at snet.net]
>
> My question re: Euphoria is whether a pointer-to-function
> scalar type or an
> eval(euphoria code here) function is in the works.
You can do pointer-to-function in a couple of ways. First, let's assume
you're talking about calling functions within Eu from Eu. You could use
routine_id's for this. It's not technically a pointer, but within a prog,
it basically works the same way.
There's also the call_back() facility. This allows dll's and the like to
call functions in your app. The call_back() is an actual pointer that calls
your Eu function. Win32Lib, for instance uses both routine_id's and
call_back's all over the place.
You can call a routine to which you have a pointer using call(), but not if
the function takes any arguments. This is mainly used for custom ASM.
If you want to call a function with arguments from a pointer, you'll have to
use something like fptr.e, which can be found in my EuCOM package (check the
archives). This will let you call a function by pointer while passing
arguments. It also gets around the 8 (now 9) argument limit for Eu
call_back's. It works by using ASM to either call the function you specify,
or 'redirect' a function call to your function and store the arguments in
memory. (NB: Bernie, I think this is all that's really needed to open up
interfacing with other languages--at least for C++ and VB, this is enough to
get you going.)
The eval() concept has been tossed around here quite a bit, but I don't
think it will happen unless someone [other than Rob]with the source figures
it out. However, there's an Eu emulator written in pure Eu (by David Cuny,
of course) that I've used to create a scripting engine (I don't have access
to it right now, but I'm sure someone on the list has it handy if you're
interested). I added custom access routines to the internal scripting
language to change actual program variables from the script. The need for
this makes it less flexible (and a lot slower) than a general eval()
statement, but still gives you a lot of power.
Matt Lewis
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