Re: local scope once again

[Asko Kauppi <askok@...>]

I wouldn't mind getting a warning about the dual-localling of  
variables (within the same scope level).

There is one case, where this can get rather nasty:

local f	-- pre-name for early reference

local function g()
	...
	f()
end

local function f()	-- WRONG!  (must be: f= function())
	...
end

Here the intention is that 'g' and 'f' are mutually calling routines,  
or for some other reason need to be introduced in this order.  If the  
code is like above, the upper 'f' is always nil, and there's NO  
warning about this until one hits it at runtime.

Funny I don't remember this being discussed before -- has it?  Any  
solution ideas?

-asko


Jerome Vuarand kirjoitti 12.12.2006 kello 22.47:

> Leo Razoumov wrote:
> > This behaviour means that all earlier local declarations of
> > the variable become completely shadowed by later local
> > declarations at the same scope. I am afraid it makes code
> > less readable.
> >
> > local x="first declaration"
> > local x="second declaration" -- the same scope
> >
> > The first line is now completely irrelevant, because its
> > version of 'x' is not accessible by regular Lua means (except
> > for debug library).
> >
> > Is there any particular reason to design Lua local scope
> > rules this way??
>
> I can't explain the initial choice for such a decision, but I  
> personally
> think this is a good thing. This gives a lot of flexibility to the
> programmer, with the only drawback being some confusion for  
> programmers
> too used to C-like scopes. You can do what you want to do with the
> syntax, but the syntax that you expected prevents me from doing some
> things I want to do (like having multiple variables with the same name
> in the same block). So that solution is the best since it allows all
> features, at the cost of *some* readability for *some* readers not  
> used
> to Lua syntax (I think that in any experienced Lua programmer mind,  
> the
> local keyword is instantly spotted as a variable creation).