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bf(C++)'s syntax allows for hi(assignment: sequential) sequential
assignments, with the assignment operator associating from right to left. In
statements like:
verb( a = b = c;)
the expression tt(b = c) is evaluated first, and its result in turn is
assigned to tt(a).
The implementation of the overloaded assignment operator we've encountered
thus far does not permit such constructions, as it returns tt(void).
This imperfection can easily be remedied using the tt(this) pointer. The
overloaded assignment operator expects a reference to an object of its
class. It can also em(return) a reference to an object of its class. This
reference can then be used as an argument in sequential assignments.
The overloaded assignment operator commonly returns a reference to the
current object (i.e., tt(*this)). The next version of the overloaded
assignment operator for the class tt(Person) thus becomes:
verb( Person &Person::operator=(Person const &other)
{
delete[] d_address;
delete[] d_name;
delete[] d_phone;
d_address = strdupnew(other.d_address);
d_name = strdupnew(other.d_name);
d_phone = strdupnew(other.d_phone);
// return current object as a reference
return *this;
})
Overloaded operators may themselves be overloaded. Consider the tt(string)
class, having overloaded assignment operators tt(operator=(std::string const
&rhs), operator=(char const *rhs)), and several more overloaded
versions. These additional overloaded versions are there to handle different
situations which are, as usual, recognized by their argument types. These
overloaded versions all follow the same mold: when necessary dynamically
allocated memory controlled by the object is deleted; new values are assigned
using the overloaded operator's parameter values and tt(*this) is returned.
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