Macro instruction

A macro (short for 'macroinstruction', from Greek μακρός 'long') in computer science is a rule or pattern that specifies how a certain input sequence (often a sequence of characters) should be mapped to a replacement output sequence (also often a sequence of characters) according to a defined procedure. The mapping process that instantiates (transforms) a macro use into a specific sequence is known as macro expansion. A facility for writing macros may be provided as part of a software application or as a part of a programming language. In the former case, macros are used to make tasks using the application less repetitive. In the latter case, they are a tool that allows a programmer to enable code reuse or even to design domain-specific languages. A macro (short for 'macroinstruction', from Greek μακρός 'long') in computer science is a rule or pattern that specifies how a certain input sequence (often a sequence of characters) should be mapped to a replacement output sequence (also often a sequence of characters) according to a defined procedure. The mapping process that instantiates (transforms) a macro use into a specific sequence is known as macro expansion. A facility for writing macros may be provided as part of a software application or as a part of a programming language. In the former case, macros are used to make tasks using the application less repetitive. In the latter case, they are a tool that allows a programmer to enable code reuse or even to design domain-specific languages. Macros are used to make a sequence of computing instructions available to the programmer as a single program statement, making the programming task less tedious and less error-prone. (Thus, they are called 'macros' because a 'big' block of code can be expanded from a 'small' sequence of characters.) Macros often allow positional or keyword parameters that dictate what the conditional assembler program generates and have been used to create entire programs or program suites according to such variables as operating system, platform or other factors. The term derives from 'macro instruction', and such expansions were originally used in generating assembly language code. Keyboard macros and mouse macros allow short sequences of keystrokes and mouse actions to transform into other, usually more time-consuming, sequences of keystrokes and mouse actions. In this way, frequently used or repetitive sequences of keystrokes and mouse movements can be automated. Separate programs for creating these macros are called macro recorders. During the 1980s, macro programs – originally SmartKey, then SuperKey, KeyWorks, Prokey – were very popular, first as a means to automatically format screenplays, then for a variety of user input tasks. These programs were based on the TSR (terminate and stay resident) mode of operation and applied to all keyboard input, no matter in which context it occurred. They have to some extent fallen into obsolescence following the advent of mouse-driven user interface and the availability of keyboard and mouse macros in applications such as word processors and spreadsheets, making it possible to create application-sensitive keyboard macros. Keyboard macros have in more recent times come to life as a method of exploiting the economy of massively multiplayer online role-playing games (MMORPGs). By tirelessly performing a boring, repetitive, but low risk action, a player running a macro can earn a large amount of the game's currency or resources. This effect is even larger when a macro-using player operates multiple accounts simultaneously, or operates the accounts for a large amount of time each day. As this money is generated without human intervention, it can dramatically upset the economy of the game. For this reason, use of macros is a violation of the TOS or EULA of most MMORPGs, and administrators of MMORPGs fight a continual war to identify and punish macro users. Keyboard and mouse macros that are created using an application's built-in macro features are sometimes called application macros. They are created by carrying out the sequence once and letting the application record the actions. An underlying macro programming language, most commonly a scripting language, with direct access to the features of the application may also exist. The programmers' text editor, Emacs, (short for 'editing macros') follows this idea to a conclusion. In effect, most of the editor is made of macros. Emacs was originally devised as a set of macros in the editing language TECO; it was later ported to dialects of Lisp. Another programmers' text editor, Vim (a descendant of vi), also has full implementation of macros. It can record into a register (macro) what a person types on the keyboard and it can be replayed or edited just like VBA macros for Microsoft Office. Vim also has a scripting language called Vimscript to create macros. Visual Basic for Applications (VBA) is a programming language included in Microsoft Office from Office 97 through Office 2019 (although it was available in some components of Office prior to Office 97). However, its function has evolved from and replaced the macro languages that were originally included in some of these applications.