Re: Switch/Case with Fallthrough

[Sean Conner <sean@...>]

It was thus said that the Great Paige DePol once stated:
> 
> >> It was thus said that the Great Paige DePol once stated:
> >> 
> >> Your examples involve the use of tables and functions, both of which are
> >> unnecessary overhead that I would not want to incur for every switch
> >> statement that is used. Actually, I am unsure how that would qualify as an
> >> optimisation really? 
> > 
> >  For space, it's not.  It's a time-optimization, as using a hash table is
> > O(1) (amortized) overhead.  Also, the table/functions are only created once,
> > during compilation.  For large switch statements with equal (or near equal)
> > probability of among cases, I would think it's a win over a cascade of
> > if/elseif statements.
> > 
> >  -spc
> 
> The only reason the current version of my patch cascades is because a) it
> worked, b) is as efficient (or a bit more so when using a global) as
> existing if/elseif/else constructs and c) supporting a jump table is not
> possible in vanilla Lua so far as I can tell at this time! :)
> 
> Yes, you could use Lua itself to create a jump table using a Lua table and
> functions, but that is not a terribly nice looking construct, 

  Who says you have to see it?  It's the compiler doing the table/function
construction, not the programmer (or the text editor).  

> and I
> believe my jump table opcode solution would still be more efficient than a
> Lua based construct. 

  Here I would suggest you actually profile the results.  

> Also, switch case statements are easy to understand,
> don't produce cluttered code and is much nicer to use than a
> table/function system, imo. :)

  Yes, but I was talking about how your langauge converts the switch
statement internally.

  -spc