Re: [PATCH] Change "refs/" references to symbolic constants

On Tuesday 2007 February 20 11:37, Johannes Schindelin wrote:

Apologies, I'm not using ternary in the sense of the number 0, 1 and 2; I'm using it in the sense of there being three possible outcomes - which there are. This is similar to how operators are categorised into unary, binary and ternary categories. I use ternary to mean "having three states or elements", rather than "having the value 0, 1 or 2".

Boolean expressions are those that have two possible states - "true" or "false". There are no real booleans in C, so they are faked. The two boolean states in C are represented by

 False = Equal to zero
 True = Not equal to zero

Now, the !! construction you suggest is perfectly in keeping with this definition. Ironically, the only reason you need the !! construction is because of this integer-as-boolean trait of C.

So, to get a boolean in C you use a standard integer (say). My contention is that to improve clarity you should not mix integer-as-boolean and integer-as-integer, even though C will accept it when you do.

 i = 10;
 while( i )
   i--;

This is bad, it abuses the fact that C will let you treat an integer as a boolean. while() takes a boolean expression as it's argument, so I think that you should always hand it something that would be a boolean output (even though C doesn't care if you don't).

 i = 10;
 while( i > 0 )
  i--;

This makes it clear to the reader that i is not boolean. Obviously this is a trivial example; no one would have any trouble understanding either of the two examples. When things start to get bigger and more complicated though, more clarity is always better than less clarity. The principle I try to follow is that code is write-once-read-many. If you save yourself two keystrokes at the expense of the clarity you gain for the 100 times you read that code, then you have made a false economy.

In the end - I don't care - I was only countering Junio's "I prefer !strcmp", with my reasons why I don't like it. I do not expect git to change to my preferred coding style, and I do try to keep to the coding style that the git project uses. To my mind, inconsistency is a worse offence than anything else in a project, so it's always better to go with what is established.

Andy