That looks right to me! On Dec 19, 2013 1:23 AM, "Marcus Ottosson" <[email protected]> wrote:
> What do you think my usage of flags within this "policy" for a > os.listdir-type object? > > class ExcludePolicy(object): > > # Flags > ExcludeHidden = 1 << 0 > ExcludeInvisible = 1 << 1 > ExcludeRegex = 1 << 2 > ExcludeFiles = 1 << 3 > > def __init__(self): > self.__flags = self.ExcludeHidden | self.ExcludeInvisible | > self.ExcludeFiles > self.__regex = '' > > @property > def regex(self): > return self.__regex > > @regex.setter > def regex(self, regex): > self.__regex = regex > > @property > def flags(self): > return self.__flags > > @flags.setter > def flags(self, flags): > self.__flags = flags > > > class ListDir(object): > def __init__(self): > self.__excludePolicy = None > > def dir(self): > if not self.__excludePolicy: > return > > pol = self.__excludePolicy > if pol.flags & pol.ExcludeHidden: > print "Excluding hidden" > > if pol.flags & pol.ExcludeInvisible: > print "Excluding invisible" > > if pol.flags & pol.ExcludeRegex: > print 'Excluding regex: "%s"' % pol.regex > > if pol.flags & pol.ExcludeFiles: > print "Excluding files" > > @property > def excludePolicy(self): > return self.__excludePolicy > > @excludePolicy.setter > def excludePolicy(self, policy): > self.__excludePolicy = policy > > > if __name__ == '__main__': > pol = ExcludePolicy() > > # pol.regex = r'^*.$' > # pol.flags = pol.ExcludeRegex > > ld = ListDir() > ld.excludePolicy = pol > ld.dir() > > > > On 18 December 2013 10:29, Marcus Ottosson <[email protected]> wrote: > >> Brilliant, that makes sense. >> >> I also came across this thread, the accepted answer is especially helpful. >> http://stackoverflow.com/questions/276706/what-are-bitwise-operators >> >> Thanks, Justin >> >> >> >> On 18 December 2013 10:11, Justin Israel <[email protected]> wrote: >> >>> They are bitwise flags. Each value in a given enum is incremented by >>> shifting bits. Then you are able to use bitwise operators to combine >>> multiple values and test their membership: >>> https://wiki.python.org/moin/BitwiseOperators >>> >>> A = 1 << 0 >>> B = 1 << 1 >>> C = 1 << 2 >>> D = 1 << 3 >>> print A,B,C,D >>> # 1 2 4 8 >>> print A | B >>> # 3 >>> print A | B | B | B >>> # 3 >>> flag = A|B >>> if flag & A: print True >>> # True >>> if flag & B: print True >>> # True >>> if flag & C: print True >>> # >>> flag ^ B # toggle off B >>> # 5 >>> flag ^ B ^ B # toggle off and on B >>> # 7 >>> flag & ~B # subtract B >>> # 5 >>> flag & ~B & ~B # maintains the subtraction (not toggle) >>> # 5 >>> flag &= ~B # unary subtraction; assignment >>> # 5 >>> >>> Basically, once you define a set of flags, you have AND, OR, XOR, NOT >>> operators to test and modify the flags. It lets you represent a number of >>> states in a single value. >>> >>> >>> >>> >>> >>> On Wed, Dec 18, 2013 at 9:00 PM, Marcus Ottosson <[email protected] >>> > wrote: >>> >>>> Hi all, >>>> >>>> What's a Pythonic way of parsing a set of flags, similar to how Qt does >>>> it. >>>> >>>> E.g. layout.setAlignment(Qt.AlignTop | Qt.AlignLeft) >>>> >>>> Both AlignTop and AlignLeft seem to be hex numbers (docs >>>> here<http://qt-project.org/doc/qt-5.1/qtcore/qt.html>) >>>> that seem to get combined into a third number via the | operator. Where's >>>> the logic behind that and how can I derive such logic myself? >>>> >>>> Thanks, >>>> Marcus >>>> >>>> -- >>>> *Marcus Ottosson* >>>> [email protected] >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "Python Programming for Autodesk Maya" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to [email protected]. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/python_inside_maya/CAFRtmOBUGHyG9vrny_BqWcdvcD3ezM-VHM_jNJYA70Rv4DTNug%40mail.gmail.com >>>> . >>>> For more options, visit https://groups.google.com/groups/opt_out. >>>> >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "Python Programming for Autodesk Maya" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/python_inside_maya/CAPGFgA1sQCWRnfP5LVZRNFpRM1uPMmNZYEikOLSFRZ%3DUGE16ig%40mail.gmail.com >>> . >>> For more options, visit https://groups.google.com/groups/opt_out. >>> >> >> >> >> -- >> *Marcus Ottosson* >> [email protected] >> > > > > -- > *Marcus Ottosson* > [email protected] > > -- > You received this message because you are subscribed to the Google Groups > "Python Programming for Autodesk Maya" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/python_inside_maya/CAFRtmODL40VrgCeZ-P%2Bc%3DwpB9feVZFd0KnC79BNtbw5xrxANeA%40mail.gmail.com > . > For more options, visit https://groups.google.com/groups/opt_out. > -- You received this message because you are subscribed to the Google Groups "Python Programming for Autodesk Maya" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/python_inside_maya/CAPGFgA26JyquVL3KKD6GtCkcuA2F%3DT9fPEr3%2BtccvJOh7c2chA%40mail.gmail.com. For more options, visit https://groups.google.com/groups/opt_out.
