.. include:: <mmlalias.txt>


Descriptors: Bound Method
=========================

Ways To Call A Method
---------------------

.. jupyter-execute::

   class Person:
       def __init__(self, name):
           self.name = name
       def greet(self, phrase):           # <-- method
           print(f'{phrase} {self.name}')

   joerg = Person('Joerg')

Two ways to call ``greet`` ...

**"On the object" directly** (as everybody does everyday), supplying
*one* parameter. ``joerg`` is "implicitly" passed as self.

.. jupyter-execute::
  
   joerg.greet('Howdy, my name is')

**Via the class**, supplying the object explicitly, as ``self``.

.. jupyter-execute::

   Person.greet(joerg, 'Howdy, my name is')

Bound Methods
-------------

**Bound method**

.. jupyter-execute::
  
   print(joerg.greet)

.. jupyter-execute::
  
   greetfunc = joerg.greet
   greetfunc('Howdy, my name is')

So, obviously a bound method brings the object with it!

**Plain function**: knows no object

.. jupyter-execute::

   print(Person.greet)

Using :doc:`functools.partial <python:library/functools>` to get
"bound method" behavior:

.. jupyter-execute::

   from functools import partial
   greetfunc = partial(Person.greet, joerg)
   greetfunc('Howdy, my name is')

And Descriptors?
----------------

* ``joerg.greet`` is an attribute |longrightarrow| :ref:`descriptor
  protocol <python-descriptor-descriptor-protocol>`
* Somehow I get a *bound method* when I say ``joerg.greet``
* So where is the descriptor?
* |longrightarrow| It's the function ``Person.greet`` itself!

.. jupyter-execute::

   print(Person.greet.__get__)     # <-- A-HA!!