Re: MySql coding style: Request for deprecation of UPPERCASE typedefs

[Mats Kindahl]

Jay Pipes wrote:
> Tor Didriksen wrote:
>> On Wed, 24 Jun 2009 17:14:03 +0200, Michael Widenius
>> <monty@stripped> wrote:
>>> There is no 'of course' in that.
>>>
>>> If you try to do every include file self-contained, you need a LOT of
>>> more includes 'just in case' and dependents that just creates more
>>> code, more parsing without giving you anything.
>>>
>>> MySQL was design with the idea that you in most cases only have to
>>> include one (but in practice a few) include files in each source file.
>>
>> #include mysql_priv which pulls in just about everything, yes.
>> This practice makes it impossible to do unit testing.
>>
>> 'include or declare what you use' is a very simple rule,
>> and makes the code much more maintainable and testable.
> 
> This is one of the first things we tackled in Drizzle.  We found that
> there was a spiderweb of #includes that made it:
> 
> * Nearly impossible to easily state which files were being included in
> the current source compilation, and more importantly *which order* files
> were being included (#ifdef MYSQL_SERVER anyone?!)
> * Difficult to determine *where* key structures and classes were defined
> (sql_class.h, sql_base.h, structs.h, definitions.h, unireg.h,
> mysql_priv.h, etc etc etc...)
> * SLOWER compilation speeds since large numbers of class and struct
> definitions needed to be "pulled in" to a source compilation for no
> reason whatsoever -- Drizzle's compilation speed has dramatically
> improved since we tackled the #include mess.
> 
> One thing I *still* haven't been able to "unplug" is the mess in
> sql_lex.h which partially compiles the parser with this wonderful block
> of ugly:
> 
> /*
>   The following hack is needed because mysql_yacc.cc does not define
>   YYSTYPE before including this file
> */
> 
> #ifdef DRIZZLE_SERVER
> # include <drizzled/set_var.h>
> # include <drizzled/item/func.h>
> # ifdef DRIZZLE_YACC
> #  define LEX_YYSTYPE void *
> # else
> #  if defined(DRIZZLE_LEX)
> #   include <drizzled/lex_symbol.h>
> #   include <drizzled/sql_yacc.h>
> #   define LEX_YYSTYPE YYSTYPE *
> #  else
> #   define LEX_YYSTYPE void *
> #  endif /* defined(DRIZZLE_LEX) */
> # endif /* DRIZZLE_YACC */
> #endif /* DRIZZLE_SERVER */
> 
> I believe this is the very last place that DRIZZLE_SERVER (MYSQL_SERVER)
> is used in the Drizzle source code.  Every time I've tried to break this
> monster up, I've gone down a rathole...but I know it's possible to do
> it.  Maybe Mats will figure it out and I can buy him a beer or two :)

Never tempt me with beer... ;)

Bison/Yacc is a mess to get right. I've done it and redone it more times than I
can count; not with MySQL though...

Best wishes,
Mats Kindahl
-- 
Mats Kindahl
Senior Software Engineer
Database Technology Group
Sun Microsystems