Architecture principles

Law of Demetr (LOD)

Base postulates

Every unit should have limited knowledge about other units: only "closely" related to the current unit

Each unit should only talk to its friends; don't talk to stangers

Only talk to your immediate friends

Links

Wiki (en): https://en.wikipedia.org/wiki/Law_of_Demeter

Why its needed (ru): https://toster.ru/q/44822

Pros

Lower dependencies between classes

Safer code change

Potentialy lower Response for Class (RFC) Metric

Cons

Wrappers time & space overhead

Layer architecture is an implementation of LOD

Chain of responsibility

Relay messages

wiki(ru): https://ru.wikipedia.org/wiki/%D0%A6%D0%B5%D0%BF%D0%BE%D1%87%D0%BA%D0%B0_%D0%BE%D0%B1%D1%8F%D0%B7%D0%B0%D0%BD%D0%BD%D0%BE%D1%81%D1%82%D0%B5%D0%B9

Command

What is metrics: https://msdn.microsoft.com/en-us/library/bb385914.aspx

Metrics types

Response for Class (RFC)

inokation complexity on message

http://staff.unak.is/andy/StaticAnalysis0809/metrics/rfc.html

lower RFC - lower bugs

Weighted Methods per Class (WMC)

Sum of complexity of all class methods

http://staff.unak.is/andy/StaticAnalysis0809/metrics/wmc.html

Optimal values: http://stackoverflow.com/questions/2033743/code-metrics-calculation-in-visual-studio