[STYLE] use true/false in C++, not TRUE/FALSE

[Guilhem Bichot]

Hello,

http://forge.mysql.com/wiki/MySQL_Internals_Coding_Guidelines
says

"Use TRUE and FALSE instead of true and false in C++ code. This makes 
the code more readable and makes it easier to use it later in a C 
library, if needed."

Proposal 1
==========
Use true/false, not TRUE/FALSE, for storing in into bool objects, or 
into bool function parameters. Do so for new code. Change existing code 
only when there's a deeper reason.

Rationale
=========
I disagree with "more readable". I find that those capital letters are 
so eye-catching that they attract too much the reader's attention, for 
example when I read those lines (from 5.1) I pay more attention to TRUE 
that to "ref", which is bad:

         if ((*group->item)->walk(&Item::find_item_processor, TRUE,
                                  (uchar *) ref))

     having->split_sum_func2(thd, ref_pointer_array, all_fields,
                             &having, TRUE);

Also, I find it strange: "bool" can take "true" or "false" by design, 
why are we forced to use something else?

Proposal 2
==========

Extend proposal 1 to using true/false for storing into my_bool C 
function parameters, and to using bool for storing the my_bool result of 
C functions.

Rationale
=========
TRUE/FALSE is needed for my_bool (which is char) in C code.
As for calls to C functions from C++, if the function takes a my_bool 
parameter, passing true/false is ok, as there would be implicit 
conversion from bool to my_bool, true becomes 1 (==TRUE), false becomes 
0 (==FALSE). Storing a my_bool result from the C function into a bool 
would also be correct (any non-zero value would become true). Thus it 
sounds possible to completely eliminate TRUE/FALSE from C++ code.

-- 
Mr. Guilhem Bichot <guilhem.bichot@stripped>
Oracle / MySQL / Optimizer team, Lead Software Engineer
Bordeaux, France
www.oracle.com / www.mysql.com