René's URL Explorer Experiment

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The SOLID design principles are five ideas that guide how you split responsibilities, add features without risky modifications, respect subtype contracts, keep interfaces focused, and depend on abstractions. You use SOLID to design classes that you can maintain, extend, and test with confidence.
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You provide each class with one clear reason to change and move unrelated behaviors into separate classes. For example, you keep file I/O in one class and ZIP compression in another, which allows you to simplify testing, improve component reusability, and reduce coupling.
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You define an abstract interface that subclasses extend without forcing edits to the existing class.
\n
For example, you create a Shape base with .calculate_area() and add Circle or Square by implementing that method instead of changing .__init__() or .calculate_area() in the base.
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You ensure that any subtype (subclass) behaves like its base type (base class) so callers don’t face surprises. 
\n
In the shapes example, you avoid making Square a Rectangle when changing .width shouldn’t silently change .height, and you instead share a Shape base with .calculate_area().
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