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The ability to use a familiar procedural language as the macro language gives power much greater than that of text substitution macros, at the expense of a larger and slower compiler. Macros in PL/I, as well as in many assemblers, may have side effects, e.g., setting variables that other macros can access.
Calling the macros requires a special precaution: namely, the first operand (the obstack pointer) should not contain any side effects, because it may be computed more than once. In ISO C, each obstack function has both a macro definition and a function definition. The function definition is used if the macro substitution fails.
A variadic macro is a feature of some computer programming languages, especially the C preprocessor, whereby a macro may be declared to accept a varying number of arguments. Variable-argument macros were introduced in 1999 in the ISO/IEC 9899:1999 ( C99 ) revision of the C language standard, and in 2011 in ISO/IEC 14882:2011 ( C++11 ) revision ...
Many compilers define additional, non-standard macros. A common reference for these macros is the Pre-defined C/C++ Compiler Macros project, which lists "various pre-defined compiler macros that can be used to identify standards, compilers, operating systems, hardware architectures, and even basic run-time libraries at compile-time."
This example aims to improve the readability of the X macro usage by: Prefix the name of the macro that defines the list with "FOR_". Pass name of the worker macro into the list macro. This both avoids defining an obscurely named macro (X), and alleviates the need to undefine it. Use the syntax for variadic macro arguments "..." in the worker ...
It is not to be confused with macros, the mechanism often found in programming languages (like C or Scala) to express substitution rules for program pieces. Macroprogramming originated in the context of wireless sensor network programming [3] [4] [5] and found renewed interest in the context of the Internet of Things [6] and swarm robotics. [7] [1]
m4 is a general-purpose macro processor included in most Unix-like operating systems, and is a component of the POSIX standard.. The language was designed by Brian Kernighan and Dennis Ritchie for the original versions of UNIX.
Some argue that there is a sharp learning curve to make complete use of metaprogramming features. [8] Since metaprogramming gives more flexibility and configurability at runtime, misuse or incorrect use of metaprogramming can result in unwarranted and unexpected errors that can be extremely difficult to debug to an average developer.