[Gambas-user] if-else vs try who are best faster inmachine time?

[PICCORO McKAY Lenz]

From: Tobias Boege <taboege at ...626...>
> Yeah, may I throw in some related thought?
>
> I know you asked for the most efficient way to do it but your program
> should
> also be safe from race conditions, right? When you do
>
> ' Check for existance
> If Exist(sPath) Then Kill sPath
>
> or even
>
> ' Check for existance and write access using short-circuit
> If Exist(sPath) And If Stat(sPath).Auth Like "?w*" Then Kill sPath
well the safe for race conditions at this point dont care to much, but
u'r response are very interesting

> Let's also consider what most probably happens at least under Linux when
> you
> have Try Kill sPath in Gambas (note that I didn't consult the real sources
> here, just guessing how it would be done): the interpreter will call the
> unlink() syscall which deletes the file or delivers an error. The error is
> propagated but suppressed by Try.
>
> With Exist(sPath) Then Kill sPath, the interpreter likely executes
> something
> like access() which can equivalently well fail or succeed. If it succeeds
> you still have to do the same unlink() operation.
>
> So, the best case you can get is that Exist() is false. Then the running
> time is roughly access() vs. unlink(). In all other cases, the Try Kill
> approach seems to be faster and safer, too.
>
> You have to decide now: Do you expect sPath non-existing most of the time?
> Do you want to ignore race conditions in favour of performance? Then use
> the
> If Exist(...) Then Kill ... method.
i like the way u defeat the try-cach.. umm but mi questio are due
try-cach internals rutines have more code to compute the race
conditions, rather than if-else, so due if-else do not compute the
race contidions obviously are more faste, of course also more
insegure!

that's all.. i currently use if-else, due write disk i already check
at start time and each day
but as u done, recomended its to use try-catch

>
> Regards,
> Tobi
>
> --

-- 
Lenz McKAY Gerardo (PICCORO)
http://qgqlochekone.blogspot.com