On Tue, 06 Dec 2005 22:51:03 -0000, Grant Edwards <[EMAIL PROTECTED]> wrote:
>On 2005-12-06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > >> The only way to get the flags is as a float, either through an >> ascii string or a true float. > >That's perverse. > >Really. > >Somebody needs to be slapped. > >> The value of the float, however, is representable as 24 bits >> of normal binary. > >OK, that should preserve a 1:1 mapping between strings/floats >and flag bit patterns. It's still sick, though. > >> So for example, the value returned is +4.608400E+04 which is >> really an int, 46084, which is more easily convertible to >> binary. > >You really don't need to convert it to "binary". Just convert >it to an integer object. > >> So the question becomes how to convert an int to binary, which >> I found here >> >> http://groups.google.com/group/comp.lang.python/browse_frm/thread/300e220394e2d841/33bc9b0d8174b038?lnk=st&q=python+int+to+binary&rnum=1#33bc9b0d8174b038 > >I doubt you actually want to do that. Just leave it as an >integer, and test for the bits you care about: > >def bit(n): > return 1<<n > >flags = int(half_assed_float_representing_the_flag_values) > >if flags & bit(0): > print "underrange" >if flags & bit(1): > print "overrange" >if flags & bit(19): > print "bit 19 is set but nobody can hear me scream" >if flags & bit(23): > callThePolice() > >or whatever. > You could also make a "whatever" like >>> class Bitview(long): ... def __new__(cls, v, width=32): ... inst = long.__new__(cls, v) ... inst.width = width ... return inst ... def __getitem__(self, i): ... if isinstance(i, slice): return list(self)[i] ... if i>=self.width or i+self.width<0: ... raise IndexError, '%r has only %r bits' %(long(self), self.width) ... if i<0: i = i + self.width ... bit = 1<<i ... return self&bit and 1 or 0 ... def __repr__(self): return "Bitview(int('%s', 2))"% str(self) ... def __str__(self): return ''.join(map(str, self))[::-1] ... >>> bv11 = Bitview(11, 8) >>> bv11 Bitview(int('00001011', 2)) >>> bv11[8] Traceback (most recent call last): File "<stdin>", line 1, in ? File "<stdin>", line 9, in __getitem__ IndexError: 11L has only 8 bits >>> list(bv11) [1, 1, 0, 1, 0, 0, 0, 0] >>> bv11[::-1] [0, 0, 0, 0, 1, 0, 1, 1] >>> bv11[-1] 0 >>> bv11[-5] 1 >>> bv11[-6] 0 >>> bv11[:4] [1, 1, 0, 1] >>> str(bv11) '00001011' >>> repr(bv11) "Bitview(int('00001011', 2))" >>> eval(repr(bv11)) == bv11 True >>> import sys >>> Bitview(sys.maxint) Bitview(int('01111111111111111111111111111111', 2)) Add niceties to taste ;-) Regards, Bengt Richter -- http://mail.python.org/mailman/listinfo/python-list
