Editing Abstraction (computer science) (section)

===Object-oriented design===
{{Further|Object-oriented design}}

Decisions regarding what to abstract and what to keep under the control of the coder become the major concern of object-oriented design and [[domain analysis]]—actually determining the relevant relationships in the real world is the concern of [[object-oriented analysis and design|object-oriented analysis]] or [[legacy analysis]].

In general, to determine appropriate abstraction, one must make many small decisions about scope (domain analysis), determine what other systems one must cooperate with (legacy analysis), then perform a detailed object-oriented analysis which is expressed within project time and budget constraints as an object-oriented design. In our simple example, the domain is the barnyard, the live pigs and cows and their eating habits are the legacy constraints, the detailed analysis is that coders must have the flexibility to feed the animals what is available and thus there is no reason to code the type of food into the class itself, and the design is a single simple Animal class of which pigs and cows are instances with the same functions. A decision to differentiate DairyAnimal would change the detailed analysis but the domain and legacy analysis would be unchanged—thus it is entirely under the control of the programmer, and it is called an abstraction in object-oriented programming as distinct from abstraction in domain or legacy analysis.