RE: Odd behaviour with multiple return values and varargs

["Tom Miles" <Tom@...>]

> >
> > > Okay, so I'm obviously missing something with this.  Can anyone 
> > > explain the behaviour from this:
> > >
> > > function test1()
> > >     return 1, 2
> > > end
> > >
> > > function test2()
> > >     return 3,4
> > > end
> > >
> > > print(test1(), test2())
> > >
> > >> 1    3    4
> > >
> > > I would have expected it to output 1    2    3    4.  Why 
> doesn't it?
> >
> > Only the last function in a comma list has multiple return values 
> > respected.
> 
> On 9/12/07, Tom Miles <Tom@creative-assembly.co.uk> wrote:
> > Is there a good reason for that?  I assume there is, but 
> I'ld like to 
> > know, as it seems a bit counter-intuitive.
> 
> At first sight, it's counter-intuitive.
> Think about how you'd write the print() function so that it 
> took multiple variadic arguments(??).
> 
> in your example "print(test1(), test2())", if the output was 
> "1 2 3 4", from the standpoint of print(), what part of the 
> output is the first argument, what part is the rest? How 
> would you write such a function in Lua?
> 

I'm not sure I understand your point.  In my mind, if I have two
functions returning 2 values, then I have 4 values plain and simple.  It
would be treated exactly the same as print(1,2,3,4).  Is there a reason
not to do it that way? 

> -- count & print the arguments one per line function myprint(...)
>    for i,v in pairs({...}) do
>       io.write(i .. ":  " .. v .. "\n")
>    end
> end
> 
> myprint(test1(), test2())
> 1:  1
> 2:  3
> 3:  4
> 
> So, I guess you're hoping the expansion of "print(test1(), test2())"
> would be "print(1,2, 3,4)" but that would be rather difficult 
> to handle for anyone writing variadic functions - consider
> 
> 
> function variadic(a, b, ...)
>    print(a, b, ...)
> end
> variadic(test1(), test2())
> 
> What should be in a? what should be in b?
>

Again, I don't see your point!  What should be in a and b, or what 'is'?
Obviously, I think that a = 1, b = 2, and ... Contains 3, and 4, but
that's not what is. :/

As I said before, there is obviously a good reason for the way it is,
greater minds than mine have formulated the language, but I don't think
you have provided me with a convincing argument.  Thanks for the
feedback though.
 
> -K
> 
> PS. Top-posting and HTML-encoded messages are generally 
> accepted as no-noes.
> 

Sorry about that.  I hope I've fixed it, but if there is a massive html
sig attached to this then I have no control over that as all outgoing
email has it added automatically by our companys mail server.
 








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