Hi All,
I would like to propose something that I have found _incredible_ useful:
Here is an example from the standard C lib:
struct tm {
int tm_sec; /* seconds after the minute [0-60] */
int tm_min; /* minutes after the hour [0-59] */
int tm_hour; /* hours since midnight [0-23] */
...
int tm_yday; /* days since January 1 [0-365] */
int tm_isdst; /* Daylight Savings Time flag */
long tm_gmtoff; /* offset from CUT in seconds */
char *tm_zone; /* timezone abbreviation */
};
The fields of the structure are prefixed.
If this is done so that field names are unique then finding all places
in the code where a field is used is very easy.
Whether debugging or just trying to understand code, this is extremely
useful.
Often you have a bug where a structure (or class) field has the wrong
value, and you need to know where the field is assigned. Now if the
field is called 'flags', you have a tough time finding all instances
because of the flood of hits.
I have often wished for this while trying to code read my way through
the MySQL optimizer to figure out why it is using the wrong query
plan. And also for answering questions like how are memory buffers
used in MySQL, as Ronald has asked.
I am not proposing that all current structures be changed. Although
that would be ideal, and easy to do with the help of the compiler. But
it is something to keep in mind for new code.
Obviously, if we do change existing structures it has to be done soon,
because it causes a merge nightmare...
Brian Aker wrote:
Hi!
This needs to be a FAQ, not an email. Here goes:
Please use stdint.h for now. http://en.wikipedia.org/wiki/Stdint.h
When writing new code always use the C99 types. GCC will give us
lint like advice if we do.
Use bool, not my_bool. Use true and false, not TRUE and FALSE (those
macro need to die).
ulong -> uint32_t
ulonglong uint64_t
long int -> int32_t
Why? Long is not portable and in MySQL there are a number of places
where we use it that I question if the code is really 64 bit clean.
When assigning please use MySQL style:
x= 4;
It is easy to search for.
When you put something together like this:
a == b && c ==j || A
Do it like:
((a == b) && (c ==j)) || A
Be generous with your use of parens. If I see them, then I know you
knew what you were doing and I do not have to worry if you really
understood operator precedent.
Encapsulate structures and classes.
Use enum, not defines. Defines are for single shot "everything will
be this". Enums create lists. If the values are going to go into a
switch/ case... they should be enums.
Please do not use "i" as an iterator in for loops. I have old
eyes... use x or spell out a variable.
Please fix indention in old code. It is a boring thing to do, but is
incredibly valuable. When someone looks at code, they will send in
patches based on what they see. Lets make it so the code looks
identical.
Do this for () {}; not for (); when you have an empty body. It gives
me a hint that you really did want just the for to loop. And while
we are at it, (void)func() calls if you are ignoring the return type.
All new classes get their own .h and .cc files. We will need to pull
apart the mess that exists today, but that is a long term goal.
Cheers,
-Brian
--
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