Re: Implementing GOTO/GOSUB

[Asko Kauppi <asko.kauppi@...>]

Okay, here's a more polished version (still, not tried). If someone 
uses it, make sure cpp doesn't add #pragma's or other such stuff in its 
output (I've used 'cpp -P -xassembler-with-cpp').

	local __retline

	#define __GOSUB(xx)  __retline='#'.. #__LINE__; __GOTO=xx; 
__LABEL='#'.. #__LINE__
	#define __RETURN     __GOTO=__retline

I know that the '__GOSUB()' syntax and '__GOTO=' syntaxes are nastily 
different; don't know a fix for this.. :(

-ak


13.9.2004 kello 20:41, Asko Kauppi kirjoitti:


> Well, you can emulate GOSUBs with GOTO, can't you.. (just conceptually,
>
> 	a=1
> 	__GOSUB=77
> 	a=2
> 	__GOSUB=77
> 	a=3
> 	__LABEL=77
> 	print(a)
> 	__RETURN
>
> Where:
> 	__GOSUB=xx:	__RETURN_TO='#'..linenum; __GOTO=xx; __LABEL='#'..linenum
> 	__RETURN:	__GOTO=__RETURN_TO
>
> This would probably need the use of C preprocessor (cpp) or something 
> alike to do the macros (& get the linenums!).  Is that out of the 
> question?
>
>
> 13.9.2004 kello 20:13, Luiz Henrique de Figueiredo kirjoitti:
>
>  I tried to implement GOTO/GOSUB functionality in Lua.
> > An year ago, prompted by a similar request here in lua-l, I wrote a 
> > simple
> > patch for luac that did the right thing for the code below:
> >
> >          a=1
> >          __GOTO=12
> >          __LABEL=99
> >          print("bye",a)
> >          do return end
> >          a=2
> >          __LABEL=12
> >          print("hello",a)
> >          a=3
> >          __GOTO=99
> >
> > That is, it turned __GOTO into JMPs and __LABEL into NOPS.
> > This worked great for GOTO but I don't think it will work for GOSUB 
> > ... RETURN.
> > --lhf