28 Feb
2022
28 Feb
'22
7:04 a.m.
The X11 tree was a heavily ifdef-ed. And it needed to
be, I don't have
an answer as to how you would reuse all that code on different hardware
in a better way.
Plan 9 did it with #include. The name of the included file was the same for
every architecture. Only the search path for include files changed. Done with
care, this eliminates the typical upfront #ifdefs.that define constants and set
flags.
Other preprocessor conditionals can usually be replaced by a regular if, letting
the compiler optimize away the unwanted alternative. This makes conditionals
obey the scope rules of C.
Doug