[Python-ideas] [Wild Idea] Static Ducks

Masklinn masklinn at masklinn.net
Sat Sep 19 12:44:56 CEST 2009

On 19 Sep 2009, at 11:16 , Steven D'Aprano wrote:
> What sort of type checking is done?
> Pascal-style declarative type checking, or Haskell-style type
> inference?
Can't answer the rest, but from his examples and if $type and  
$returnType are indeed type specifications placeholders (which would  
be the ducks), it would be a java-style static type system (…).

And it would probably be run at "compile" time given the name, doing  
the checking at runtime wouldn't be very static.

As far as I'm concerned, it's a terrible idea. Because it doesn't fit  
well within Python as a dynamically typed language, because the syntax  
is ugly, because Java's C-inherited type prefixes look terrible and  
are extremely verbose, because Java's type system is pretty bad and  
finally because the proposal doesn't handle "generic" types, making it  
completely useless.

I also haven't seen any example of typing an instance attribute, the  
only example involving classes creates a class attribute:

    class test:
        $type variable = value

        $returnType def method(self, $type variable):
            #do stuff
            return value

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