Level of indirection software#

The aim is to allow end users to manage their homes without requiring detailed technical knowledge or programming ability. To start with a simple example the variables x, y and z in an equation such as z = x 2 + y 2 means the set of all formulae - so although the reference is to α there are two levels of indirection here, the first to the set of all α and then the second to a specific formula for each occurrence of α in the set Δ.An approach is presented for flexible management of smart homes, covering both home automation and telecare. When doing symbolic programming from a formal mathematical specification the use of indirection can be quite helpful. Recursive data types are usually implemented using indirection, because otherwise if a value of a datatype can contain the entirety of another value of the same datatype, there is no limit to the size a value of this datatype could need. 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. 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. (6) It is easier to move a problem around (for example, by moving the problem to a different part of the overall network architecture) than it is to solve it. An often cited corollary to this is, '.except for the problem of too many layers of indirection.'Ī humorous Internet memorandum, RFC 1925, insists that: This is often deliberately mis-quoted with ' abstraction layer' substituted for 'level of indirection'.

Level of indirection software#

The indirection from human-readable names to network addresses means that the references to a web page become more memorable, and links do not need to change when a web site is relocated to a different server.Ī famous aphorism of Butler Lampson goes: 'All problems in computer science can be solved by another level of indirection' (the ' fundamental theorem of software engineering'). In some older computer architectures, indirect words supported a variety of more-or-less complicated addressing modes.Īnother important example is the domain name system which enables names such as en. to be used in place 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 (also called dereferencing) is the ability to reference something using a name, reference, or container instead of the value itself. JSTOR ( February 2022) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.