<filename>recipes/Python/106469_Yet_another_Set_class_for_Python/recipe-106469.py
class Set:
    """The set class. It can contain mutable objects."""

    def __init__(self, seq = None):
        """The constructor. It can take any object giving an iterator as an optional
        argument to populate the new set."""
        self.elems = []
        if seq:
            for elem in seq:
                if elem not in self.elems:
                    self.elems.append(elem)

    def __str__(self):
        return "{%s}" % ", ".join(map(str, self.elems))


    def copy(self):
        """Shallow copy of a set object."""
        return Set(self.elems)

    def __contains__(self, elem):
        return elem in self.elems

    def __len__(self):
        return len(self.elems)

    def items(self):
        """Returns a list of the elements in the set."""
        return self.elems

    def add(self, elem):
        """Add one element to the set."""
        if elem not in self.elems:
            self.elems.append(elem)

    def remove(self, elem):
        """Remove an element from the set. Return an error if elem is not in the set."""
        try:
            self.elems.remove(elem)
        except ValueError:
            raise LookupError, "Object %s is not a member of the set." % str(elem)

    def discard(self, elem):
        """Remove an element from the set. Do nothing if elem is not in the set."""
        try:
            self.elems.remove(elem)
        except ValueError:
            pass

    #Define an iterator for a set.
    def __iter__(self):
        return iter(self.elems)

    #The basic binary operations with sets.
    def __or__(self, other):
        """Union of two sets."""
        ret = self.copy()
        for elem in other.elems:
            if elem not in ret:
                ret.elems.append(elem)
        return ret

    def __sub__(self, other):
        """Difference of two sets."""
        ret = self.copy()
        for elem in other.elems:
            ret.discard(elem)
        return ret

    def __and__(self, other):
        """Intersection of two sets."""
        ret = Set()
        for elem in self.elems:
            if elem in other.elems:
                ret.elems.append(elem)
        return ret

    def __add__(self, other):
        """Symmetric difference of two sets."""
        ret = Set()
        temp = other.copy()
        for elem in self.elems:
            if elem in temp.elems:
                temp.elems.remove(elem)
            else:
                ret.elems.append(elem)
        #Add remaining elements.
        for elem in temp.elems:
                ret.elems.append(elem)
        return ret

    def __mul__(self, other):
        """Cartesian product of two sets."""
        ret = Set()
        for elemself in self.elems:
            ret.elems.extend([(elemself, elemother) for elemother in other.elems])
        return ret

    #Some of the binary comparisons.
    def __lt__(self, other):
        """Returns 1 if the lhs set is contained but not equal to the rhs set."""
        if len(self.elems) < len(other.elems):
            temp = other.copy()
            for elem in self.elems:
                if elem in temp.elems:
                    temp.remove(elem)
                else:
                    return 0
            return len(temp.elems) == 0
        else:
            return 0

    def __le__(self, other):
        """Returns 1 if the lhs set is contained in the rhs set."""
        if len(self.elems) <= len(other.elems):
            ret = 1
            for elem in self.elems:
                if elem not in other.elems:
                    ret = 0
                    break
            return ret
        else:
            return 0

    def __eq__(self, other):
        """Returns 1 if the sets are equal."""
        if len(self.elems) != len(other.elems):
            return 0
        else:
            return len(self - other) == 0

<filename>recipes/Python/106469_Yet_another_Set_class_for_Python/recipe-106469.py
class Set:
    """The set class. It can contain mutable objects."""

    def __init__(self, seq = None):
        """The constructor. It can take any object giving an iterator as an optional
        argument to populate the new set."""
        self.elems = []
        if seq:
            for elem in seq:
                if elem not in self.elems:
                    self.elems.append(elem)

    def __str__(self):
        return "{%s}" % ", ".join(map(str, self.elems))


    def copy(self):
        """Shallow copy of a set object."""
        return Set(self.elems)

    def __contains__(self, elem):
        return elem in self.elems

    def __len__(self):
        return len(self.elems)

    def items(self):
        """Returns a list of the elements in the set."""
        return self.elems

    def add(self, elem):
        """Add one element to the set."""
        if elem not in self.elems:
            self.elems.append(elem)

    def remove(self, elem):
        """Remove an element from the set. Return an error if elem is not in the set."""
        try:
            self.elems.remove(elem)
        except ValueError:
            raise LookupError, "Object %s is not a member of the set." % str(elem)

    def discard(self, elem):
        """Remove an element from the set. Do nothing if elem is not in the set."""
        try:
            self.elems.remove(elem)
        except ValueError:
            pass

    #Define an iterator for a set.
    def __iter__(self):
        return iter(self.elems)

    #The basic binary operations with sets.
    def __or__(self, other):
        """Union of two sets."""
        ret = self.copy()
        for elem in other.elems:
            if elem not in ret:
                ret.elems.append(elem)
        return ret

    def __sub__(self, other):
        """Difference of two sets."""
        ret = self.copy()
        for elem in other.elems:
            ret.discard(elem)
        return ret

    def __and__(self, other):
        """Intersection of two sets."""
        ret = Set()
        for elem in self.elems:
            if elem in other.elems:
                ret.elems.append(elem)
        return ret

    def __add__(self, other):
        """Symmetric difference of two sets."""
        ret = Set()
        temp = other.copy()
        for elem in self.elems:
            if elem in temp.elems:
                temp.elems.remove(elem)
            else:
                ret.elems.append(elem)
        #Add remaining elements.
        for elem in temp.elems:
                ret.elems.append(elem)
        return ret

    def __mul__(self, other):
        """Cartesian product of two sets."""
        ret = Set()
        for elemself in self.elems:
            ret.elems.extend([(elemself, elemother) for elemother in other.elems])
        return ret

    #Some of the binary comparisons.
    def __lt__(self, other):
        """Returns 1 if the lhs set is contained but not equal to the rhs set."""
        if len(self.elems) < len(other.elems):
            temp = other.copy()
            for elem in self.elems:
                if elem in temp.elems:
                    temp.remove(elem)
                else:
                    return 0
            return len(temp.elems) == 0
        else:
            return 0

    def __le__(self, other):
        """Returns 1 if the lhs set is contained in the rhs set."""
        if len(self.elems) <= len(other.elems):
            ret = 1
            for elem in self.elems:
                if elem not in other.elems:
                    ret = 0
                    break
            return ret
        else:
            return 0

    def __eq__(self, other):
        """Returns 1 if the sets are equal."""
        if len(self.elems) != len(other.elems):
            return 0
        else:
            return len(self - other) == 0

The set class. It can contain mutable objects. The constructor. It can take any object giving an iterator as an optional         argument to populate the new set. Shallow copy of a set object. Returns a list of the elements in the set. Add one element to the set. Remove an element from the set. Return an error if elem is not in the set. Remove an element from the set. Do nothing if elem is not in the set. #Define an iterator for a set. #The basic binary operations with sets. Union of two sets. Difference of two sets. Intersection of two sets. Symmetric difference of two sets. #Add remaining elements. Cartesian product of two sets. #Some of the binary comparisons. Returns 1 if the lhs set is contained but not equal to the rhs set. Returns 1 if the lhs set is contained in the rhs set. Returns 1 if the sets are equal.