Re: RFC: booleans and the kernel

[Jamie Lokier <lk@tantalophile.demon.co.uk>]

Helge Hafting wrote:
> Why would anyone want to write   if (X==false) or if (X==true) ?
> It is the "beginner's mistake" way of writing code.  Then people learn,
> and write if (X) or if (!X).  Comparing to true/false is silly.
> Nobody writes  if ( (a==b) == true) so why do it in the simpler cases?

I usually without the == in these cases:

  if (pointer)  // test for non-0.
  if (condition)
  if (condition-valued-variable)

but not in these (although I am not very consistent):

  if (integer != 0)
  if (char != 0)

When using bool, I'm happy to write "if (X)" where X is a truth value
indicating a condition that has been tested, but if X were used as an
enumeration of truth values e.g. as in a theorem prover or a logic
simulator, I would tend to write ==, for example:

  if (X == true && ptr && *ptr > 1)

The point being to illustrate the intent of the test (i.e. is it a
boolean test or a comparison against a point in a range of values), not
simply for it to be semantically correct.

Just to break that rule, however, if p were a pointer and x were an
integer, I would write:

  x = (p != 0);

rather than

  x = p;

:-)

enjoy,
-- Jamie