[Python-ideas] Adding __getter__ to compliment __iter__.

[Ron Adam]

On 07/18/2013 01:51 AM, Clay Sweetser wrote:
> What is the difference between this "getter protocol" and using a
> generator's send method?

A protocol specifies how something is done and what's required to do it.

A generators send method is just a send method on any generator.


The Protocol in this case, is each iterable object has a __getter__ method 
that uses its' send() method to receive an iterable object for the purposes 
of extending the instance.  (or returning a new instance if it's a mutable 
object.)

Cheers,
    Ron


> On Jul 18, 2013 2:47 AM, "Ron Adam"
> <ron3200 at gmail.com
> <mailto:ron3200 at gmail.com>> wrote:
>
>
>
>     These methods would be called by a getter function which starts it by
>     calling next on it before returning it.
>
>
>     def getter(container):
>          """ Get a getter from a container object. """
>          g = container.__getter__()
>          next(g)
>          return g
>
>
>     On 07/18/2013 01:12 AM, Ron Adam wrote:
>
>
>
>         A __getter__ method on a list object might be..
>
>              def __getter__(self):
>                  def g():
>                      seq = yield
>                      self.extend(seq)
>                      return self
>                  gtr = g()
>                  next(gtr)       # start it, so send method will work.
>                  return gtr
>
>
>     Replace these last three lines with...
>
>               return g()
>
>
>     And the same for the rest of these.
>         Ron
>
>
>
>         And on a dictionary:
>
>               def __getter__(self):
>                   def g():
>                       seq = yield
>                       self.update(seq)
>                       return self
>                   getter = g()
>                   next(getter)
>                   return getter
>
>
>         on a string:    (bytes and tuples are very much like this.)
>
>               def __getter__(self):
>                    def g():
>                       seq = yield
>                       return self + seq
>                    getter = g()
>                    next(getter)
>                    return getter
>
>         etc... It's pretty simple, but builtin versions of these would not
>         need to
>         use the 'extend', 'update', or '__add__' methods, but can do the
>         eqivalent
>         directly bypassing the method calls.
>
>
>         Then what you have is a input protocol that complements the iter output
>         protocol.
>
>
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