ABCs -> infix syntax for isinstance() ?

[Bruno Desthuilliers]

Boris Borcic a écrit :
> Given the ABC innovation, maybe an infix syntax for isinstance() would 
> be good.
> 
> Possibilities :
> 
> - stealing "is" away from object identity. As a motivation, true use 
> cases for testing object identity are rare; 

"x is None" is a *very* common test. Using a _marker object as default 
arg value when you want to accept None as a meaningfull value is pretty 
common. Testing a class identity often happens when writing metaclasses.