RE: My wish list :) [RE: How can we make lua better?]

[RLake@...]

>> 2) += and -= operators
>Vote: NO

> I vote yes.  This is actually a huge thorn, IMO, and makes scripts much
> more verbose than they need to be:

> Table1.table2.table3.table4.value += 1

> OR:

> Table1.table2.table3.table4.value =
>   Table1.table2.table3.table4.value + 1

> OR:

> local tempTable = Table1.table2.table3.table4
> tempTable.value = tempTable.value + 1

> I choose the first one.  Additionally, the first one allows the Lua VM
> to make certain optimizations that make it WAY faster than #2 and even
> faster than #3.

The problem with the "certain optimizations" is that they may not be
correct in the face of tag methods.

Unless a "getset" tagmethod is implemented, it is hard to see how to know
when the optimization
could be made. (And then we'd need "indexset", too, I suppose.)

Nonetheless, with carefully defined semantics, I think this could be a
valuable addition; it would be really nice for cases like:

a[expensive_computation(i)] += 1

(which should be syntactic sugar for:

do local _index = expensive_computation(i)
     a[_index] = a[_index] + 1
end

without any other attempt to optimize).

A generalisation to multiple assignment sort of suggests itself.

For another justification of idioms like this, there is a nice paper on
Todd Proebstring's pages which mentions the high cost (to the programmer)
of thinking up names of unnecessary variables.