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| -rw-r--r-- | cppawk-narg.1 | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/cppawk-narg.1 b/cppawk-narg.1 index c0d6c4f..c9f30a0 100644 --- a/cppawk-narg.1 +++ b/cppawk-narg.1 @@ -453,6 +453,24 @@ to produce an identical macro called This then allows for two "recursion" levels, whereby each one uses the macro under a different name. +Both +.B "narg()" +and +.B "narg(x)" +expand to 1. This is a "feature" of the preprocessor: the empty +argument list is indistinguishable from an empty argument, because +preprocessor arguments are not required to be non-empty sequences +of tokens. For instance if +.B mac +is a macro which may be called with two arguments, then +.B "mac(,)" +is a valid call, which passes two empty arguments. Consequently, +if the comma is deleted from the syntax, then there is one empty argument. +The number of arguments is the number of commas plus one. This is why +.B narg +is specified as taking one or more arguments: it is not possible for +any macro to be given fewer arguments than one. + .SH AUTHOR Kaz Kylheku <kaz@kylheku.com> |