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Add coercions

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This commit is contained in:
Guido van Rossum 1993-10-27 09:28:23 +00:00
parent b6957e434f
commit f1bbf9c308
1 changed files with 12 additions and 2 deletions
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14
Demo/classes/Rat.py
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@ -52,12 +52,18 @@ class Rat:
raise TypeError, 'Rat.__coerce__: bad other arg' raise TypeError, 'Rat.__coerce__: bad other arg'
def __add__(a, b): def __add__(a, b):
if type(b) <> type(a):
a, b = a.__coerce__(b)
return a + b
return rat(a.num*b.den + b.num*a.den, a.den*b.den) return rat(a.num*b.den + b.num*a.den, a.den*b.den)
def __sub__(a, b): def __sub__(a, b):
return rat(a.num*b.den - b.num*a.den, a.den*b.den) return rat(a.num*b.den - b.num*a.den, a.den*b.den)
def __mul__(a, b): def __mul__(a, b):
if type(b) <> type(a):
a, b = a.__coerce__(b)
return a * b
return rat(a.num*b.num, a.den*b.den) return rat(a.num*b.num, a.den*b.den)
def __div__(a, b): def __div__(a, b):
@ -78,9 +84,13 @@ def test():
l.sort() l.sort()
print l print l
print rat(0, 1) print rat(0, 1)
print rat(1, 0)
print a+1 print a+1
print a+1L print a+1L
print a+1.0 print a+1.0
try:
print rat(1, 0)
raise SystemError, 'should have been ZeroDivisionError'
except ZeroDivisionError:
print 'OK'
test() #test()