[DB-SIG] Optional DB API Extensions

Federico Di Gregorio fog@debian.org
24 Oct 2001 15:56:47 +0200

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On Wed, 2001-10-24 at 15:41, Magnus Lyck=E5 wrote:
> Just as a little annoying suggestion: If you do want your
> generic high performance code inside this big loop, you
> could instead of
> ---
> while biiiig loooop:
>     ret =3D might.work()
>     if ret =3D=3D -1:
>        ret =3D SomeOtherWayOfFindingOut()
>     use(ret)
> ---
> do it like this
> ---
> itWorks =3D 1
> while biiiig loooop:
>    if itWorks:
>      try:
>        ret =3D might.work()
>      except NotImplemented:
>        itWorks =3D 0
>        ret =3D SomeOtherWayOfFindingOut()
>    else:
>      ret =3D SomeOtherWayOfFindingOut()
>    use(ret)
> ---
> You will only get one exception. You don't call might.work()
> more than one time if it fails. You also get as many ifs in
> both cases. This should be as fast if might.works() is in
> order, and faster if it isn't.

exceptions are there for exceptional circumstances (have you ever tried
timing ifs and excepts? ifs are at least 30x faster in python [1.5.x,
when i did the experiment]).

anyway, while talking about coding styles (a little OT, i know) i think
it is better to cleany separate the feature-peeking part from the rest
of the code. i.e.,

if might.work() =3D=3D None: feature_x_present =3D 0
else: feature_x_present =3D 1
while biiig looop:
    if feature_x_present:

but all that is personal taste, off curse.=20

have fun,

Federico Di Gregorio
Debian GNU/Linux Developer & Italian Press Contact        fog@debian.org
INIT.D Developer                                           fog@initd.org
             A short story: I want you. I love you. I'll miss you. -- Me

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