Re: suggestions for new version
[
Date Prev][
Date Next][
Thread Prev][
Thread Next]
[
Date Index]
[
Thread Index]
- Subject: Re: suggestions for new version
- From: Mark@... (Mark Ian Barlow)
- Date: 1997年3月01日 21:47:09 GMT
wish[1] An efficient case selection structure would be nice, to avoid the
overhead of long if-elseif...else-end constructs. I can do something
similar (but not very efficient) now with:
dostring(switch_list[selector])
...or with a table of functions which are used for their side-effects,
but it would be hard for someone else reading the code to see what was
happening; much better to localise the code at the point in the source
where it is to be used.
I presume it would be fairly easy for the compiler to plant a hidden
jump table without requiring any new opcodes or anything.
I'm not very bothered about having C's "fall-through" switch
architecture, however. I'd happily give up typing 'break' at the
end of cases and just accept an implicit and un-overrideable one.
I don't really miss 'for' loops, but the above is an efficieny issue
so I thought I'd raise it.
wish[2] A hook into the raw uncompiled input before the lexer sees it, so I
can use a regexp parser to add my own syntactic sugar for the "end
user". I can see a use for this in providing meaningful operations
on userdata, and it would fit in well with lua's policy regarding
debugging: don't provide a pre-processor, just the hooks to allow
one to be built.
Other minor things:
* hex literals and bit-operators are useful if you are talking to hardware,
but the operators would need a new fallback for the cases where casting
a double to an int leads to loss of information (a 'range' fallback?).
I've implemented the operators as functions (looks ugly) and patched
"lex.c" manually to get the literals already, so _my_ vote goes to
the form '#1234abcd' (case-insensitive), since that would give me
*forwards* compatibility! ;-)
* iolib lacks the converse of ascii(str), but it's trivial to write
a C function for char(n).
That's just about all I can think of; I *like* the elegant terseness in
lua so I wouldn't want to see a great deal more...
--
Mark Ian Barlow Non-Linear Control Consultants Ltd.
-----------------------------------------------------------------
Mark@nlcc.demon.co.uk Voice / Fax: +44 (0)1207 562 154