<<DEITEL - Python How to Program 2002>>Special attributes of an object of a class.0.0.0.3

Attribute Description
__class__ A reference to the class from which the object was instantiated.
__dict__ A dictionary that corresponds to the object’s namespace. Each keyvalue pair represents an identifier and its value in the namespace.

代码

# Fig. 7.1: Time1.py
# Simple definition of class Time.

class Time:
"""Time abstract data type (ADT) definition"""

def __init__( self ):
"""Initializes hour, minute and second to zero"""

self.hour = 0     # 0-23
self.minute = 0   # 0-59
self.second = 0   # 0-59

def printMilitary( self ):
"""Prints object of class Time in military format"""

print "%.2d:%.2d:%.2d"  % ( self.hour, self.minute, self.second )

def printStandard( self ):
"""Prints object of class Time in standard format"""

standardTime = ""

if self.hour == 0 or self.hour == 12:
standardTime += "12:"
else:
standardTime += "%d:" % ( self.hour % 12 )

standardTime += "%.2d:%.2d" % ( self.minute, self.second )

if self.hour < 12:
standardTime += " AM"
else:
standardTime += " PM"

print standardTime,

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# (C) Copyright 2002 by Deitel & Associates, Inc. and Prentice Hall.     #
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##########################################################################

Time1.Time
>>> print time1.__dict__
{'second': 0, 'minute': 0, 'hour': 0}
>>> print time1.doc
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: Time instance has no attribute 'doc'
>>> print time1.__doc__
Time abstract data type (ADT) definition
>>> print time1.__module__
Time1
>>>