Single Responsibility Principle - a practical application
Many times during the lifetime of a project I find myself writing something like this: method A(){ ... var something = B(); ... } method B(){ ... var somethingElse = C(); ... } It doesn't take long to realize that this could be written in a different way: method A(){ ... var somethingElse = C(); var something = B(somethingElse); ... } method B(somethingElse){ ... } The problem is - which way should I prefer? Which way is "better"? I have struggled with this for a while now. Today I just realized something: SRP (as applied to methods) says each method should only have one reason to change. (I was reading this article when I had this epiphany.) If something changes in C(), that effect will "ripple" to both B and A in the first case. In the second case, it is much more likely that it will only affect A. Which is fine - it is A's responsibility to "join together" the two other methods, so it's ok if it's affected by them....