mORMot Open Source

tbo

Member

Registered: 2015-04-20

Posts: 335

Please avoid negation in variable names

I've already addressed this naming in another thread, and I seem to recall that you wanted to consider it more often in the future. Avoid negations in variable names. At these points in the source code I always have to stop and think twice if I have understood it correctly. And now I read:

constructor TTextWriter.CreateOwnedStream(aBuf: pointer; aBufSize: integer; NoSharedStream: boolean);
begin
  if (not NoSharedStream) and TextWriterSharedStreamSafe.TryLock then
    fStream := TextWriterSharedStream

Why not write better without rethinking:

constructor TTextWriter.CreateOwnedStream(aBuf: pointer; aBufSize: integer; UseSharedStream: boolean);
begin
  if UseSharedStream and TextWriterSharedStreamSafe.TryLock then
    fStream := TextWriterSharedStream

With best regards
Thomas

ab

Administrator

From: France

Registered: 2010-06-21

Posts: 14,225

Website

Re: Please avoid negation in variable names

It is a biais I have indeed. I suppose it comes from the asm the compiler generates in such case.
A default value to false is shorter in asm than a default value to true.
For false, you store zero in a register, which is just a xor on self register on Intel/AMD, or you use the Zero register on ARM.

I guess it does not make any difference here, because this parameter is mainly for internal use.
Almost no "normal" user would change the default value