LEVEL OF INDIRECTION CODE

The first cost of indirection is cognitive load. Instead of having application logic directly couple to a 3rd party dependency, creating an abstraction of the repository allows you to couple to a type that you own (although I’ll argue later I don’t have to). In the case of the repository, its purpose is to abstract the dependency on Entity Framework Core.

LEVEL OF INDIRECTION CODE

Let your application code focus on application logic and let ASP.NET Core handle HTTP. To start with, the usage of MediatR can be benefiting from not coupling your application code with ASP.NET Core. Now I’m not implying you should remove indirection! There are clear benefits. I’ve left Entity Framework as a layer because ultimately you’d be using some type of data access client to get to the database, regardless if that’s Entity Framework or simply ADO.NET directly. Below is a from the OrderController that has a route to show the signed-in users Orders. I’m going to be showing snippets from the eShopOnWeb reference application. Indirection can come from a message queue, topics, load balancer, etc. If you’ve ever used the decorator pattern or created a request pipeline (check out my post on Separating Concerns with Pipes & Filters), you’re creating indirection.Īnother way to think about indirection which isn’t directly related to application code is infrastructure. This can often be thought to if you’re creating some type of data abstraction layer, a repository, etc.

Adding indirection is a useful way of isolating complexity, allowing re-use, and abstracting dependencies as we can have many different callers use the same abstraction.Ī typical example of indirection is adding an abstraction of data access. It’s not inherently bad and comes with a lot of benefits. In strongly typed interpreted languages with dynamic datatypes, most variable references require a level of indirection: first the type of the variable is checked for safety, and then the pointer to the actual value is dereferenced and acted on.As developers, we’re adding indirection all the time without really thinking of it. Delegation is another classic example of an indirection pattern. Higher-level examples of indirection are the design patterns of the proxy and the proxy server. Object-oriented programming makes use of indirection extensively, a simple example being dynamic dispatch. It is always possible to add another level of indirection. It is easier to move a problem around than it is to solve it.

Humorous Internet memorandum RFC 1925 insists that: Kevlin Henney's corollary to this is, '.except for the problem of too many layers of indirection.'

In some older computer architectures, indirect words supported a variety of more-or-less complicated addressing modes.Ī famous aphorism of David Wheeler goes: 'All problems in computer science can be solved by another level of indirection' this is often deliberately mis-quoted with 'abstraction layer' substituted for 'level of indirection'. A stored pointer that exists to provide a reference to an object by double indirection is called an indirection node. For example, accessing a variable through the use of a pointer. The most common form of indirection is the act of manipulating a value through its memory address. In computer programming, indirection is the ability to reference something using a name, reference, or container instead of the value itself. Freebase (0.00 / 0 votes) Rate this definition:

Level of indirection