Design Principle: loose coupling / principle of least knowledge / law of demeter / information hiding / incrementally grow systems

design-principle-loose-coupling.md

Design principle: loose coupling

corollary of principle of least privilege

example

object a b c
a calls b and should know nothing about b's internal structure
if c is inside b, a should know nothing about c
the mistake is: you could write a to call c(inside b) which would introduce coupling and harder debugging

implementation:

the law can be stated simply as "use only one dot". That is, the code a.m().n() breaks the law where a.m() does notTradeoffs

pros:

more maintainable code

cons:

more verbose code, requires more wrapper methods for call propagation to components

etymology:

Demeter is the greek goddess of agriculture(growth)
Demeter-style software development is about growing systems incrementally instead of monolithically building software

https://en.wikipedia.org/wiki/Law_of_Demeter

tags: design principles, information hiding, least privilege, loose coupling,