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Defining Operator '<' for Strict Weak Ordering on Tuples
For an n-tuple to satisfy strict weak ordering, it must fulfill the following criteria:
While boost library offers a pre-defined tuple class with operator '<' adhering to strict weak ordering, you may wish to define your own operator for a specific context.
Here's how you can implement operator '<' manually:
struct S { ThingA a; ThingB b; }; bool operator<(S const& lhs, S const& rhs) { return std::make_tuple(lhs.a, lhs.b) < std::make_tuple(rhs.a, rhs.b); }
In this example, we leverage the std::make_tuple function to create a tuple from the individual elements of S without copying them. Then, we compare the tuples using the generic tuple comparison operator.
For operator '==', you can follow a similar approach:
bool operator==(S const& lhs, S const& rhs) { return std::make_tuple(lhs.a, lhs.b) == std::make_tuple(rhs.a, rhs.b); }
Remember that these implementations assume that ThingA and ThingB have their own operator '<' and operator '==' defined for strict weak ordering.
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