Version 5.0 The LEDA User Manual

(c) If y is the copy of a value x of type T, then compare(x,y) == 0 must hold.
10. (Requirements for hashed types) In addition to the Requirements for type parameters
a hashed type must implement
a hash function
an equality operator
int Hash(const T&)
bool operator == (const T&, const T&)
Here, for the function Hash() the following must hold:
(a) It must be put in the namespace leda.
(b) For all objects x and y of type T: If x == y holds, then so does
Hash(x) == Hash(y).
For the equality operator operator==() the following must hold:
(a) It defines an equivalence relation on T.
(b) If y is a copy of a value x of type T, then x == y must hold.
11. (Requests for numerical types) In addition to the Requirements for type parameters
a numerical type must offer the arithmetical operators operator+(),
operator-(), and operator*(), as well as the comparison operators operator=(), operator==(), and operator!=().
B.2 Code examples for the LEDA rules
1. string s("Jumping Jack Flash");
string t(s); // definition with initialization by copying
string u = s; // definition with initialization by copying
stack S;
// ... fill S with some elements
stack T(S); // definition with initialization by copying
2. (a) list_item it1, it2;
// ...
it2 = it1; // it2 now references the same container as it1
(b) array A, B;
// ...fill A with some elements...
B = A;
Now B contains the same number of integers as A, in the same order, with the
same values.
However, A and B do not contain the same objects:
int* p = A[0];
int* q = B[0];
p == q; // false