lumiera_/doc/technical/library/Dependencies.txt

Singletons and Dependency Handling
==================================
:Date: 2018
:Toc:

WARNING: [red]#under construction# +
         There is a rather complete page ``DependencyFactory'' in the TiddlyWiki,
         which should be integrated here

We encounter _dependencies as an issue at implementation level:_ In order to deal with some task at hand,
sometimes we need to arrange matters way beyond the scope of that task. We could just thoughtlessly reach out and
settle those extraneous concerns -- yet this kind of pragmatism has a price tag: we are now mutually dependent
with internals of some other part of the system we do not even care much about. A more prudent choice would be
to let ``that other part'' provide a service for us, focussed to what we actually need right here to get _our_
work done. In essence, we create a dependency to resolve issues of coupling and to reduce complexity
(»divide et impera«).

Unfortunately this solution created a new problem: how do we get at our dependencies? We can not just step ahead
and create them or manage them, because then we'd be ``back to square one''. Rather someone else has to care.
Someone _needs to connect us with those dependencies,_ so we can use them. This is a special meta-service known
as _Dependency Injection_. A dedicated part of the application wires all other components, so each component
can focus on its specific concern and abstract away everything else. Dependency Injection can be seen as
application of the principle »Inversion Of Control«: each part is sovereign within its own realm, but becomes
a client (asks for help) for anything beyond that.


Requirements
------------
_tbw_

Configuration
~~~~~~~~~~~~~
_tbw_

Performance
~~~~~~~~~~~
_tbw_

Architecture
------------