Copy-and-paste programming

Copy-and-paste programming, sometimes referred to as just pasting, is the production of highly repetitive computer programming code, as produced by copy and paste operations. It is primarily a pejorative term; those who use the term are often implying a lack of programming competence. It may also be the result of technology limitations (e.g., an insufficiently expressive development environment) as subroutines or libraries would normally be used instead. However, there are occasions when copy-and-paste programming is considered acceptable or necessary, such as for boilerplate, loop unrolling (when not supported automatically by the compiler), or certain programming idioms, and it is supported by some source code editors in the form of snippets. Copy-and-paste programming is often done by inexperienced or student programmers, who find the act of writing code from scratch difficult or irritating and prefer to search for a pre-written solution or partial solution they can use as a basis for their own problem solving. (See also Cargo cult programming) Inexperienced programmers who copy code often do not fully understand the pre-written code they are taking. As such, the problem arises more from their inexperience and lack of courage in programming than from the act of copying and pasting, per se. The code often comes from disparate sources such as friends' or co-workers' code, Internet forums, code provided by the student's professors/TAs, or computer science textbooks. The result risks being a disjointed clash of styles, and may have superfluous code that tackles problems for which new solutions are no longer required. A further problem is that bugs can easily be introduced by assumptions and design choices made in the separate sources that no longer apply when placed in a new environment. Such code may also, in effect, be unintentionally obfuscated, as the names of variables, classes, functions and the like are typically left unchanged, even though their purpose may be completely different in the new context.