dictionary lab | Python Fiddle

"""
  Dictionary class, and two implementations

>>> d = Dictionary()
>>> d.put('Dave', 4973)
>>> d.put('J.D.', 4993)
>>> d.put('CS lab', 1202)
>>> d.lookup('Dave')
4973

>>> d.put('Dave', 1202)  # when Dave is working in the lab
>>> d.lookup('Dave')
1202
>>> d.lookup('CS lab')
1202

>>> d.lookup('Steven')
'No entry'

>>> d2 = d.withEntry('Steven', 1203)
>>> d.lookup('Steven')
'No entry'

>>> d2.lookup('Steven')
1203

# Add some tests of "merge" here

"""
# make Python look in the right place for logic.py, or complain if it doesn't
try:
    import sys
    sys.path.append('/home/courses/python')
    from logic import *
except:
    print "Can't find logic.py; if this happens in the CS teaching lab, tell your instructor"
    print "   If you are using a different computer, add logic.py to your project"
    print "   (You can download logic.py from http://www.cs.haverford.edu/resources/software/logic.py)"
    sys.exit(1)

class Dictionary1:
    """
        A dictionary represented with a Python list.
        Each list element is a tuple of two parts, the key and the value
    """
    def __init__(self):
        precondition(True)
        self.__listOfPairs = []

# "extending" constructor method: 'with'
    #  d.withEntry(k, v) has all the key/value pairs of d, together with a new entry
    def withEntry(self, key, value):
        precondition(True)
        result = Dictionary1()
        result.__listOfPairs = [ (key, value) ] + self.__listOfPairs
        return result

# axioms:
    #  Dictionary().lookup(x) === "No entry"
    #  d.withEntry(k, v).lookup(x) === v, if k==x
    #                          or d.lookup(x), otherwise
    def lookup(self, key):
        precondition(True)
        for pair in self.__listOfPairs:
            if pair[0] == key:
                return pair[1]
        return "No entry"

# axioms:
    #  d.put(k, v) --> new d is d.withEntry(k, v)
    def put(self, key, value):
        precondition(True)
        self.__listOfPairs = [ (key, value) ] + self.__listOfPairs

def __eq__(self,otherDictionary):
        precondition( isinstance(otherDictionary,Dictionary1) )
        if len(self.rep) != len(otherDictionary.rep):
            return False
        for x in self.rep, y in otherDictionary.rep:
            if x != y or self.rep[x] != otherDictionary.rep[y]:
                return False
        return True
    
    def __eq__(self,otherDictionary):
      precondition( isinstance(otherDictionary,Dictionary1) )  
        if self.__repr__() != otherDictionary.__repr__():
            return False
        return True

# axioms:
    #  fill these in
    def merge(self, otherDictionary):
        precondition( isinstance(otherDictionary,Dictionary1) )
                dict = {}
        for x in self.rep:
			dict[(x[0])] = x[1]
        for y in otherDictionary.rep:
            dict[(y[0])] = y[1]
        return dict
  
    def merge(self, otherDictionary):
        precondition( isinstance(otherDictionary,Dictionary1) )
		return self.rep + otherDictionary.rep
   
    
    def __repr__(self):
        precondition(???)
		return str(self.rep)

def __repr__(self):
        precondition(???)
        dict = {}
        for x in self.rep:
			dict[(x[0])] = x[1]
        return dict

# by default, use the first representation, but this is changed in DocTest below
Dictionary = Dictionary1

# mostly copied from  http://docs.python.org/lib/module-doctest.html
def _test():
    import doctest
    global Dictionary
    whatever_dictionary_was = Dictionary

print "=========================== Running doctest tests for Dictionary1 ===========================\n"
    Dictionary = Dictionary1
    result = doctest.testmod()
    if result[0] == 0:
        print "Wahoo! Passed all", result[1], __file__.split('/')[-1],  "tests!"
    else:
        print "Rats!"

print "\n\n\n\n"
    print "=========================== Running doctest tests for Dictionary2 ===========================\n"
    Dictionary = Dictionary2
    result = doctest.testmod()
    if result[0] == 0:
        print "Wahoo! Passed all", result[1], __file__.split('/')[-1],  "tests!"
    else:
        print "Rats!"
    Dictionary = whatever_dictionary_was

if __name__ == "__main__":
    _test()

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