adapted to new overloading scheme
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Guido van Rossum
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74233b34e1
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@ -16,7 +16,7 @@
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# Date objects support one visible method, date.weekday(). This returns
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# the day of the week the date falls on, as a string.
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#
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# Date objects also have 4 (conceptually) read-only data attributes:
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# Date objects also have 4 read-only data attributes:
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# .month in 1..12
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# .day in 1..31
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# .year int or long int
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@ -33,6 +33,11 @@
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# Tim Peters tim@ksr.com
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# not speaking for Kendall Square Research Corp
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# Adapted to Python 1.1 (where some hacks to overcome coercion are unnecessary)
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# by Guido van Rossum
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# vi:set tabsize=8:
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_MONTH_NAMES = [ 'January', 'February', 'March', 'April', 'May',
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'June', 'July', 'August', 'September', 'October',
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'November', 'December' ]
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@ -81,6 +86,7 @@ def _num2date( n ): # return date with ordinal n
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raise TypeError, 'argument must be integer: ' + `type(n)`
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ans = Date(1,1,1) # arguments irrelevant; just getting a Date obj
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del ans.ord, ans.month, ans.day, ans.year # un-initialize it
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ans.ord = n
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n400 = (n-1)/_DI400Y # # of 400-year blocks preceding
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@ -93,7 +99,7 @@ def _num2date( n ): # return date with ordinal n
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year, n = year + more, int(n - dby)
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try: year = int(year) # chop to int, if it fits
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except ValueError: pass
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except (ValueError, OverflowError): pass
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month = min( n/29 + 1, 12 )
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dbm = _days_before_month( month, year )
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@ -118,6 +124,12 @@ class Date:
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self.month, self.day, self.year = month, day, year
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self.ord = _date2num( self )
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# don't allow setting existing attributes
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def __setattr__( self, name, value ):
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if self.__dict__.has_key(name):
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raise AttributeError, 'read-only attribute ' + name
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self.__dict__[name] = value
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def __cmp__( self, other ):
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return cmp( self.ord, other.ord )
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@ -132,52 +144,27 @@ class Date:
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self.day,
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_MONTH_NAMES[self.month-1] ) + `self.year`
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# automatic coercion is a pain for date arithmetic, since e.g.
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# date-date and date-int mean different things. So, in order to
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# sneak integers past Python's coercion rules without losing the info
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# that they're really integers (& not dates!), integers are disguised
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# as instances of the derived class _DisguisedInt. That this works
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# relies on undocumented behavior of Python's coercion rules.
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def __coerce__( self, other ):
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if type(other) in _INT_TYPES:
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return self, _DisguisedInt(other)
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# if another Date, fine
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if type(other) is type(self) and other.__class__ is Date:
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return self, other
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# Python coerces int+date, but not date+int; in the former case,
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# _DisguisedInt.__add__ handles it, so we only need to do
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# date+int here
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# Python 1.1 coerces neither int+date nor date+int
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def __add__( self, n ):
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if type(n) not in _INT_TYPES:
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raise TypeError, 'can\'t add ' + `type(n)` + ' to date'
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return _num2date( self.ord + n )
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__radd__ = __add__ # handle int+date
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# Python coerces all of int-date, date-int and date-date; the first
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# case winds up in _DisguisedInt.__sub__, leaving the latter two
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# for us
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# Python 1.1 coerces neither date-int nor date-date
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def __sub__( self, other ):
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if other.__class__ is _DisguisedInt: # date-int
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return _num2date( self.ord - other.ord )
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if type(other) in _INT_TYPES: # date-int
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return _num2date( self.ord - other )
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else:
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return self.ord - other.ord # date-date
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# complain about int-date
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def __rsub__( self, other ):
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raise TypeError, 'Can\'t subtract date from integer'
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def weekday( self ):
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return _num2day( self.ord )
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# see comments before Date.__add__
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class _DisguisedInt( Date ):
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def __init__( self, n ):
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self.ord = n
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# handle int+date
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def __add__( self, other ):
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return other.__add__( self.ord )
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# complain about int-date
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def __sub__( self, other ):
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raise TypeError, 'Can\'t subtract date from integer'
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def today():
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import time
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local = time.localtime(time.time())
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@ -189,9 +176,7 @@ def test( firstyear, lastyear ):
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b = Date(9,30,1914)
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if `a` != 'Tue 30 Sep 1913':
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raise DateTestError, '__repr__ failure'
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if (not a < b) or a == b or a > b or b != b or \
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a != 698982 or 698982 != a or \
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(not a > 5) or (not 5 < a):
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if (not a < b) or a == b or a > b or b != b:
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raise DateTestError, '__cmp__ failure'
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if a+365 != b or 365+a != b:
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raise DateTestError, '__add__ failure'
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@ -1,7 +1,10 @@
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# Rational numbers
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from types import *
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def rat(num, den):
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if type(num) == FloatType or type(den) == FloatType:
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return num/den
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return Rat(num, den)
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@ -16,12 +19,21 @@ class Rat:
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def __init__(self, num, den):
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if den == 0:
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raise ZeroDivisionError, 'rat(x, 0)'
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g = gcd(num, den)
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if type(den) == FloatType or type(num) == FloatType:
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g = float(den)
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else:
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g = gcd(num, den)
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self.num = num/g
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self.den = den/g
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def __repr__(self):
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return 'rat' + `self.num, self.den`
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return 'Rat(%s, %s)' % (self.num, self.den)
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def __str__(self):
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if self.den == 1:
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return str(self.num)
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else:
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return '%s/%s' % (self.num, self.den)
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def __cmp__(a, b):
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c = a-b
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@ -42,29 +54,23 @@ class Rat:
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def __coerce__(a, b):
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t = type(b)
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if t == type(0):
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return a, rat(b, 1)
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if t == type(0L):
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return a, rat(b, 1L)
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if t == type(0.0):
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return a.__float__(), b
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if t == type(a) and a.__class__ == b.__class__:
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if t == IntType:
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return a, Rat(b, 1)
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if t == LongType:
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return a, Rat(b, 1L)
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if t == FloatType:
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return a, Rat(b, 1.0)
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if t == InstanceType and a.__class__ == b.__class__:
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return a, b
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raise TypeError, 'Rat.__coerce__: bad other arg'
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def __add__(a, b):
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if type(b) <> type(a):
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a, b = a.__coerce__(b)
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return a + b
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return rat(a.num*b.den + b.num*a.den, a.den*b.den)
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def __sub__(a, b):
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return rat(a.num*b.den - b.num*a.den, a.den*b.den)
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def __mul__(a, b):
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if type(b) <> type(a):
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a, b = a.__coerce__(b)
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return a * b
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return rat(a.num*b.num, a.den*b.den)
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def __div__(a, b):
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@ -75,21 +81,21 @@ class Rat:
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def test():
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print rat(-1L, 1)
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print rat(1, -1)
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a = rat(1, 10)
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print Rat(-1L, 1)
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print Rat(1, -1)
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a = Rat(1, 10)
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print int(a), long(a), float(a)
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b = rat(2, 5)
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b = Rat(2, 5)
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l = [a+b, a-b, a*b, a/b]
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print l
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l.sort()
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print l
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print rat(0, 1)
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print Rat(0, 1)
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print a+1
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print a+1L
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print a+1.0
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try:
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print rat(1, 0)
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print Rat(1, 0)
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raise SystemError, 'should have been ZeroDivisionError'
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except ZeroDivisionError:
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print 'OK'
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