FreeTDS Development Group

["Lowden, James K" <LowdenJK AT bernstein.com>]

> From: ZIGLIO Frediano [mailto:Frediano.Ziglio AT vodafoneomnitel.it]
> Sent: February 13, 2003 9:26 AM
> 
> I'm merging some patch.
> There are many replaces of #ifdef with #if in such way:
> From
>   #ifdef DMALLOC
> to
>   #if DMALLOC
> What's the right (or better) method ?

Consistency is more important than the choice itself, IMO.  

Some data:

$ grep -r --no-file \#if include src |grep -v 'if 0' |perl -ne'
chop; 
($if, @macro)=split; 
$macro = join " ", @macro; 
if(/ifn*def/){ 
        $ifdef{$macro}++; 
} else { 
        $if{$macro}++; 
} 
$macro{$macro}++; 
END{ 
        printf "9999\tif\tifdef\n"; 
        foreach $m (sort keys %macro){ 
                printf "%d\t%d\t%d\t$m$/", 
                        ($if{$m}+$ifdef{$m}), 
                        $if{$m}, $ifdef{$m};
        } 
}' |sort -rn |head -25
9999    if      ifdef
121     121     0       HAVE_CONFIG_H
99      98      1       HAVE_STRING_H
82      81      1       HAVE_STDLIB_H
42      0       42      __cplusplus
28      4       24      WORDS_BIGENDIAN
27      0       27      DMALLOC
19      18      1       HAVE_UNISTD_H
18      18      0       (ODBCVER >= 0x0300)
11      11      0       TIME_WITH_SYS_TIME
10      10      0       HAVE_ICONV
7       7       0       HAVE_NETINET_IN_H
7       1       6       MSDBLIB
6       0       6       ENABLE_DEVELOPING
6       6       0       HAVE_ERRNO_H
6       6       0       HAVE_SYS_SOCKET_H
6       0       6       UNIXODBC
6       0       6       _REENTRANT
5       5       0       HAVE_ARPA_INET_H
5       5       0       HAVE_SYS_TYPES_H
4       0       4       MICROSOFT_DBLIB
4       3       1       TDS42
4       0       4       WIN32
3       3       0       (ODBCVER >= 0x300)
3       0       3       COMMON_h

It looks like "HAVE_" macros are clearly in the "if" camp, while DMALLOC is
consistently used with "ifdef".  I tend to use #ifdef mostly to prevent
duplicate #includes.  Probably a C++ habit. 

In the particular case of DMALLOC, I suspect Brian made a careful choice.
DMALLOC replaces malloc(), and you can't have two kinds of heap allocation
in a single program (unless you're *extremely* careful with free()).  You
might conceivably want to defeat DMALLOC's behavior in a particular file,
but you wouldn't want to mix allocation schemes.  

--jkl


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