The direction of dependency within the application should be in the direction of abstraction, not implementation details.
#PRINCIPLE APP UI REDDIT HOW TO#
A key consideration in domain-driven design and clean architecture is how to encapsulate access to data, and how to ensure application state is not made invalid by direct access to its persistence format. It's worth noting that data-driven architectures which rely on a central database for integration within and between applications are, themselves, choosing to depend on the mutable global state represented by the database. Understanding concerns with mutable global state is one of the reasons programming languages like C# have support for different scoping rules, which are used everywhere from statements to methods to classes. A value fetched from mutable global state in one function cannot be relied upon to have the same value in another function (or even further in the same function). Mutable global state is antithetical to encapsulation. This approach frees the application's internal design to evolve over time without worrying that doing so will break collaborators, so long as the public contracts are maintained. Likewise, application components and applications themselves should expose well-defined interfaces for their collaborators to use, rather than allowing their state to be modified directly. If an outside actor wants to manipulate the state of the object, it should do so through a well-defined function (or property setter), rather than having direct access to the private state of the object. In classes, encapsulation is achieved by limiting outside access to the class's internal state. Proper use of encapsulation helps achieve loose coupling and modularity in application designs, since objects and packages can be replaced with alternative implementations so long as the same interface is maintained. Application components and layers should be able to adjust their internal implementation without breaking their collaborators as long as external contracts are not violated. Encapsulationĭifferent parts of an application should use encapsulation to insulate them from other parts of the application. Separation of concerns is a key consideration behind the use of layers in application architectures. This separation helps ensure that the business model is easy to test and can evolve without being tightly coupled to low-level implementation details (it also helps if infrastructure concerns depend on abstractions defined in the business layer). Ideally, business rules and logic should reside in a separate project, which should not depend on other projects in the application. The behavior responsible for choosing which items to format should be kept separate from the behavior responsible for formatting the items, since these behaviors are separate concerns that are only coincidentally related to one another.Īrchitecturally, applications can be logically built to follow this principle by separating core business behavior from infrastructure and user-interface logic. For instance, consider an application that includes logic for identifying noteworthy items to display to the user, and which formats such items in a particular way to make them more noticeable.
#PRINCIPLE APP UI REDDIT SOFTWARE#
This principle asserts that software should be separated based on the kinds of work it performs. Common design principles Separation of concernsĪ guiding principle when developing is Separation of Concerns. Generally, these principles will guide you toward building applications out of discrete components that are not tightly coupled to other parts of your application, but rather communicate through explicit interfaces or messaging systems.
The principles outlined in this section can help guide you toward architectural decisions that will result in clean, maintainable applications. You should architect and design software solutions with maintainability in mind.
"If builders built buildings the way programmers wrote programs, then the first woodpecker that came along would destroy civilization." - Gerald Weinberg
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