[Python-ideas] pep-0484 - Forward references and Didactics - be orthogonal

[Prof. Dr. L. Humbert]

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On 25.08.2015 17:15, Terry Reedy wrote:
> You did not say why you think this is bad.  Is it a) students have to
> type "'"s?, or b) the resulting annotations are strings instead of the
> class?

Ok, the answer for short: a)
Pls let me explain it a bit:

> As you should know, at least after reading previous responses, making
> this work would require one of two major changes to Python class
> statements.

1st class pedagogical/didactical thinking …
Consider: there are recursive defined ADTs and we want to enable
students to understand concepts and produce python-code to realize, what
they understood.

The main point:
if the students already understood, that it is possible to place type
hints to place type hints for arguments and results of functions/methods
they should be able to reuse the notation in an orthogonal manner.

For example:
>>> def b (first: int, second: str) -> List[bool]:
...   print(first)
...   return [second.find(str(first))>=0]
...
>>> b(34, "Die 13 langen Nasen rauben ihm (34J) den Schlaf")
34
[True]
>>>

When it comes to recursive ADTs they should be able to write
>>> class Tree:
...   def __init__(self, left: Tree, right: Tree):
...     self.left = left
...     self.right = right


TNX
Ludger
- -- 
https://twitter.com/n770
http://ddi.uni-wuppertal.de/
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