Re: OOBit

[Christopher Eykamp <chris@...>]

 On 9/29/2010 2:47 PM, HyperHacker wrote:
> > > >>  There are no confusing similar concepts. Dot is "get value" and
> > > >>  colon is "call". Easy to grasp, isn't it?
> > >
> > >  But dot also means call.
> > >
> It's a matter of perspective. Both retrieve the value; one returns it
> (and you might immediately call afterward); the other is only valid if
> you're calling it in the same expression.
Like so:

a.doit       -- get value
a.doit()     -- call with no parameters
a:doit()     -- call with implied parameter a
a:doit       -- invalid (though could just as logically be equivalent to 
a.doit)

My argument is that the semantic difference between the second and third 
is small; that the eye will easily mistake a dot and a colon; and that 
can lead to difficult to find errors, especially (but not only) for 
those who also use languages where there is no difference between the 
dot usage and the colon usage.  My conclusion is that replacing the 
colon with something that less resembles a dot would improve the situation.

> I like the idea myself of declaring a function differently such that
> the 'self' parameter is automatic without needing to use a colon.
That would be my preferred solution.

> However it has some potential ambiguity:
> a={}
> method a.b() print(self) end
> a.b() --should print the address of a
> n = a.b
> n() --???
I may be completely missing the subtlety of these examples, but in this 
case, I would expect n() to print the address of n, because n now refers 
to "print(self)" and self here is n.
> c = {b=a.b, d=a.b, e=n}
> c.b() --prints a, or c?
> c.d() --prints a, or c?
> c.n() --???
Here I would expect c, c, and c for the same reason, assuming when you 
wrote c.n() you meant c.e().

c.b() is the same as c:b(), which (in unaltered Lua) is equivalent to 
c.b(c), so self would be c.