What's the best way to minimize the need of run time checks?

[BartC]

On 12/08/2016 23:12, Lawrence D’Oliveiro wrote:
> On Friday, August 12, 2016 at 9:39:11 PM UTC+12, BartC wrote:
>
>> 'year' has been spelled wrongly
>
> That’s why Python has __slots__.

OK. So when I said:

 >
 > My example was specifically about attribute names where pre-declaring
 > the set of allowed attributes would not be onerous, would be usefully
 > self-documenting, and would allow more errors to be picked up.

it turns out someone implemented just that!

Although it doesn't sound like Python to bolt-on some random feature 
that reins in its dynamic capabilities. Most people here seem to be 
against limiting the language in any way.

 > (Of course the design of Python makes that impractical because it
 > would
 > require the byte-code compiler to see inside imported modules before
 > execution is commenced.)

And the scheme I had in mind would detect the problem at compile-time.

The '__slots__' feature can't do that (unless someone uses a very clever 
'linter'), but it will actually detect an attribute mismatch at runtime 
instead of silently creating an extraneous one.

-- 
Bartc