How to implement SOLID principles into an existing project

Question

Sorry for the subjective nature of this topic, but I'm stuck, and I'd appreciate any assistance and advise from anyone who's faced this problem before:

I'm working on a large RESTful API project in C# 2.0, and some of my classes have grown to be enormous. With several dozen members and functions, my main API class is an example of this (probably approaching hundreds). As you might imagine, not only is maintaining this code becoming a pain, but simply navigating the code has become a chore.

I'm fairly new to SOLID principles, however I'm a huge lover of design patterns (but I am still at that stage where I can implement them, but not quite enough to know when to use them - in situations where its not so obvious).

I need to reduce the number of my classes, but I'm not sure how to go about doing so. Any ideas guys?

Answer 1

It will be a lengthy procedure. You must read the code and refactor any areas that do not adhere to the SOLID principles into new classes. The refactoring process can be aided by using a Visual Studio add-in like Resharper (http://www.jetbrains.com).

In an ideal world, you'll have a large number of automated unit tests to ensure that your changes don't break the code.

Additional Information

You must discover methods that are related to one another in the primary API class and develop a class that more explicitly defines the operations that the method does.

Ex.

Assume I have an Address class with different variables for street number, name, and so on. This class is in charge of inserting, updating, and deleting data. I could create a method named GetFormattedPostalAddress() that returned the formatted address if I also required to format an address in a specific way for a postal address.

Alternatively, I might rework this method into a class named AddressFormatter, which takes an Address as a function Object() { [native code] } parameter and returns the formatted address via a Get property called PostalAddress.

The goal is to divide various responsibilities into distinct classes.