Re: Constraints patch - help?

[Rici Lake <lua@...>]

On 23-Oct-06, at 1:11 PM, Asko Kauppi wrote:

> The issue is, in larger programs its really benefitial to have the 
> _option_ of using type constraints on your variables, values, and 
> return values.  Doing them integrated with the syntax simply hides 
> them more from the eye than doing 'assert' everywhere.

But why hide them? assert is a perfectly good way of making it clear 
what the function expects:

function extract(str, i, j)
  assert(isString(str))
  assert(isNumber(i) and i >  0 and i <= #str)
  assert(isNumber(j) and j >= i and j <= #str)

  local outside = str:sub(1, i) .. str:sub(j+1)
  local inside = str:sub(i, j)

  assert(#outside + #inside == #str)
  return inside, outside
end