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Roman Mogilatov 2015-08-03 22:36:20 +03:00
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docs/introduction.rst
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Introduction
============
Before you have started with *Objects* framework and dependecy injection, there
are a couple of introduction notes that might be useful.
What is DI and why is it needed?
--------------------------------
Python ecosystem consists of a big amount of various libraries that contain
different classes and functions that could be used for applications
development. Each of them has its own role.
@ -10,26 +16,46 @@ source systems / frameworks / libraries and some turnkey functionality.
When application goes bigger, its complexity and SLOC_ are also increased.
Being driven by SOLID_ (for example), developers often start to split
application's sources into not so big classes, functions and modules. It
always helps, but there is another problem on the horizon.
application's sources into not so big classes, functions and modules, that are
less complex, could be reused several times and so on... It always helps, but
there is another problem on the horizon.
It sounds like "I have so many classes and functions! They are great, now I can
understand each of them, but it is so hard to see the whole picture! How are
they linked with each other? What dependencies does this class have?". And
this is a key question: "What dependencies do certain class / function have?".
To resolve this issues developers have to go inside with IoC_ principles and
implementation patterns.
The name of this problem is - "Dependency hell!". It sounds like "I have so
many classes and functions! They are great, now I can understand each of them,
but it is so hard to see the whole picture! How are they linked with each
other? What dependencies does this class have?". And this is a key question:
"What dependencies do certain class / function have?". To resolve this issues
developers have to go inside with IoC_ principles and implementation patterns.
One of such IoC_ implementation patterns is called `dependency injection`_.
*Objects* is a dependency injection framework for Python projects.
Dependency injection in Python
------------------------------
It was designed to be developer's friendly tool for managing any kind of
Python objects and their dependencies in formal, pretty way.
Interesting but, dependency injection is not very popular topic in Python.
The things are so because Python is an awesome language. Your eyes are opened
and your hands are free while you are using Python. In practice this means that
you can do dependency injection in Python in quite an easy way because language
itself helps you to do this. At the same time, even the thins are so, you still
have to do some work. Another one 'minor' problem is that there are several
ways to do dependency injection container.
Key features
------------
*Objects* is a dependency injection framework for Python projects.
It was designed to be unified, developer's friendly tool for managing any kind
of Python objects and their dependencies in formal, pretty way.
Below is a list of some key features and points of *Objects* framework:
- Easy, smart, pythonic style.
- Obvious, clear structure.
- Memory efficiency.
- Semantic versioning.
Main idea of *Objects* is to keep dependencies under control.
.. _SLOC: http://en.wikipedia.org/wiki/Source_lines_of_code
.. _SOLID: http://en.wikipedia.org/wiki/SOLID_%28object-oriented_design%29
.. _IoC: http://en.wikipedia.org/wiki/Inversion_of_control