Re: how to prevent bugs without static type checking?

[Geoff Leyland <geoff_leyland@...>]

On 25/10/2012, at 8:43 AM, eugeny gladkih <john@gladkih.com> wrote:

>>     --- prints the string s n times
>>     -- @tparam number n how many times to print the string
>>     -- @tparam string s the string to print
>>     function printn(s, n)
>>       for i = 1, n do print(s) end
>>     end
>> 
>>     printn(10, "hello")
> 
> what about
> 
> printn("hello",'10')
> 
> ?

As in, does the "number" constraint check whether tonumber (or automatic type coercion) can coerce the argument into a number?  Currently, no, it just does 'type(value) == constraint'.  It'd be easy to change, but I get the feeling automatic coercion is not always a popular feature.

But you can go:

function printn(
  s, -- string
  n) -- number|string

or, for that matter

function printn(
  s, -- string
  n) -- 1..640: 640 ought to be enough for anybody

and so on.