prev up next   top/contents search

comp.lang.c FAQ list · Question 10.2

Q: Here are some cute preprocessor macros:

	#define begin	{
	#define end	}
With these, I can write C code that looks more like Pascal. What do y'all think?

A: Use of macros like these, though perhaps superficially attractive, is generally discouraged; in severe cases the practice is called ``preprocessor abuse.''

There is little to be gained in trying to redefine the syntax of a language to fit your own predilections, or to match some other language. Your predilections are unlikely to be shared by later readers or maintainers of the code, and any simulation of another language is most unlikely to be perfect (so any alleged convenience or utility will probably be outweighed by the nuisance of remembering the imperfections).

As a general rule, it's a good idea if the use of preprocessor macros follows the syntax of the C language. Macros without arguments should look like variables or other identifiers; macros with arguments should look like function calls. Ask yourself: ``If I somehow presented this code to the compiler without running it through the preprocessor, how many syntax errors would I get?'' (Of course, you'd get plenty of undefined symbols and non-constant array dimensions, but those aren't syntax errors.) This rule means that C code, plus macro invocations, still looks like C code. So-called nonsyntactic macros like begin and end or CTRL(D) (see question 10.21) can make C look like gobbledygook (see also question 20.36).

This is of course largely a style issue; see also section 17.

prev up next   contents search
about this FAQ list   about eskimo   search   feedback   copyright

Hosted by Eskimo North