SoC - Separation Of Concerns¶

• Single Responsibility Principle and SoC are strongly related
• Implies separation of different [[concern]]s in different modules
• Allows to build [[modular system]]s

Concerns we often face with: - [[UI]] - [[Business Logic]] - [[Presentation Logic]] - [[Database]]

Leaking abstractions can ruin the SoC¶

presentation layer is bothered by [[UI]] concerns

public Color TextColor
{
    get {
        bool result = Validate(text)
        return result ? Colors.Green : Colors.Red;
    }
}

[[Domain]] is bothered by [[Database]]:

void DoWork(Customer customer1, Customer customer2)
{
    if (customer1.Id > 0) {
        // do something
    }

    if (customer1.Id == customer2.Id) {
        // do something
    }
}

• [[Layer]]s which represent different concerns should be isolated from each other in such a way that none of them should know a bout any intrinsic details of each other.
• [[SQL procedure]]s implementing [[business logic]] violate SoC but they're way much faster in certain scenarios.