From: Paul Eggert > [...] > It's maintainability. For example, if a typo had > been inadvertently put into the old 32-bit code > (a misspelled identifier, say, due to someone typing > a character by mistake), it would not have been caught > by someone compiling on the 64-bit platform. But with > the new code, compiling on one platform verifies the > syntax on all platforms. This is an inherent advantage > of "if (...)" over "#if ...", and it's an advantage we've > come to appreciate over time.
This argument would be more compelling if "is syntactically correct" and "works properly" were equivalent. Sadly, they're not, so I tend to believe that any environment-specific code really needs to be tested in the specific environment where it isn't all optimized into oblivion. > In this particular example, there's another maintainability > advantage to the new code: it has one copy of the > magic hexadecimal constants, not two. So testing on a > 64-bit platform also helps to test that these constants are > right on a 32-bit platform. The old code didn't have this > property. And it's impossible/impractical to arrange this commonality using #define (et al.)? > > I've used a bundled C compiler on HP-UX, > > which has been (intentionally) crippled to the extent of disabling the > > "-O" option(s). > > As have I, but that's doesn't trump maintainability. > For us, maintainability is more important than minor > performance issues on obsolete or crippled systems. I remain unconvinced of these claimed advantages. (But it's not my code.) ------------------------------------------------------------------------ Steven M. Schweda sms@antinode-info 382 South Warwick Street (+1) 651-699-9818 Saint Paul MN 55105-2547
