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--- about:navigating_principle_languages [2013-09-14 15:55] – code DataImpl christian
+++ about:navigating_principle_languages [2013-09-14 18:05] – christian
@@ Line 164: / Line 164: @@
 So LC, RoE and TdA/IE are against the solution, KISS thinks it's good and ML has nothing against it. As it is not the number of principles which is important, the designer still has to make a sound judgment based on these results. What is more important: Coupling, testability, and clarity or a simple and fast implementation. In this case we'd rather decide that the former are more important, so we should rather think about a better solution.
+==== Deciding between Alternatives ====
+In the next step we would think about better alternatives and might come up with [[patterns:dependency injection]] and [[patterns:service locators]]. So there are three alternatives (with several variations): The current solution and the two new ideas.
+We already constructed a characterizing set. So the only thing to do is to rate the ideas according to the principles:
+The current "factory" approach is abbreviated "F", dependency injection is DI and SL stands for service locator. In the following a rough, informal rating is described, where "A > B" means that the respective principle rates A higher/better than B. "=" stands for equal ratings.
+  * LC
+    * DI > SL > F
+    * Note that in the SL approach there is an additional coupling to the service locator
+  * KISS
+    * F > DI = SL
+    * All three solutions are rather simple but in DI there is complexity for passing around the references and in the SL approach there is complexity in maintaining the registry
+  * RoE
+    * The rating of RoE depends on the concrete variant of the pattern. In the DI approach the dependencies are explicitly visible on the interface, which is not the case in the two other approaches. In solution F the dependency is not visible from the interface at all. Same with SL if the service locator is globally accessible. Even if a reference to the service locator is explicitly passed around, it is still not visible which services provided by the locator are used. On the other hand getting a reference is explicit with F and SL. In the DI approach it is only explicit when it is done manually. Typical DI frameworks wire the instances implicitly.
+  * TdA/IE
+    * FIXME
+  * ML