OpenEuphoria

Re: Comments on ORAC

• Posted by Mike <vulcan at win??o.nz> Nov 12, 2007
• 639 views

Matt Lewis wrote:
> 
> Mike wrote:

> > Now, if the Euphoria internals were modified to have said mask, Orac could
> > only
> > take advantage of this for routines called as procedures since it'd have to
> > emit
> > some "if" statements. Therefore, routines called as functions (in an
> > expression)
> > just wouldn't work.
> 
> I think you're overcomplicating this.  Since you're writing a preprocessor,
> you just need to create a global function and a global procedure, something
> like:
> }}}
<eucode>
> global function call_indirect_function( integer func, sequence args )
>     if and_bits( func, C_FUNC_INDIRECT ) then
>         return c_func( and_bits( func, ROUTINE_MASK ), args )
> 
>     elsif and_bits( func, EU_FUNC_INDIRECT ) then
>         return call_func( and_bits( func, ROUTINEMASK ), args )
>     end if
>     -- error handling here...
> end function
> </eucode>
{{{

> 
> Matt


Hi Matt,

Now why didn't I think of that, :-o  Yes, that would work. However, routines
called as procedures would need to be encapsulated in a function call since 
it won't be known beforehand if a func or proc is being referenced. Orac 
allows (normal) functions to act like procedures so, to be consistent, that
should be possible for indirect functions too. To the programmer it'll all
look the same so it had better act the same.

Therefore, the mask requires 2 pieces of info: indirect vs dll  and  func vs
proc.

This throws up a subtle gotcha: Since indirect calls of both kinds could be
treated as functions, what happens if a  procedure is inadvertently used in
an expression? The code will work but be wrong. 

I think a bit mask would be a good idea if Euphoria were fully modified to
*natively* support seamless calls. But if this  were done in conjunction with
Orac the code analysis it does now would still need to be done in order to be
able to optimize certain calls - as Pete suggested.

But since indirect calls will always be slower than direct ones, is there really
any point to optimizing? If not, then, there is no point to analysing the code
either. I have no qualms about suspending the code I've just written - it's a
hack anyway.

If this mask were added to Euphoria, what (other than Orac) could take
advantage of it? I would feel uncomfortable if Euphoria were modified just
to suit Orac - particularly when I'm inclined to something else.

IMO, an easier solution is simply to add a specifier to a variable/constant
declaration. I am going to do this shortly unless someone can convince me
otherwise with very persuasive arguments.


Mike