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With Constructor based injection its easier to see layering and coupling issues as once your constructor gets more that 3-4 parameters then it starts becoming b

With Constructor based injection its easier to see layering and coupling issues as once your constructor gets more that 3-4 parameters then it starts becoming blindingly obvious that the class has too many dependencies and needs to be refactored. This helps keep the bad out of the architecture. The main reason to favor constructor based injection is that it stops objects becoming 'live' in an inconsistent state. I've seen actual production issues with setter based injection that can only be explained by the object being available for use before all the setters have been called.

ivan_gammel 10y ago
Your arguments are valid on why constructor injection should be preferred. However, what are you talking about is the human-made decision: "Stop adding more parameters to constructor". The tool does not force you to build high-quality architecture, it is your choice based on your experience and skills. Other people who are not yet aware about the consequences may still make wrong design decisions and they'll be ok with lots of parameters.