(Note: tuple
and tie
can be taken from Boost or C++11.)
When writing small structs with only two elements, I sometimes tend to choose a std::pair
, as all important stuff is already done for that datatype, like operator<
for strict-weak-ordering.
The downsides though are the pretty much useless variable names. Even if I myself created that typedef
, I won't remember 2 days later what first
and what second
exactly was, especially if they are both of the same type. This gets even worse for more than two members, as nesting pair
s pretty much sucks.
The other option for that is a tuple
, either from Boost or C++11, but that doesn't really look any nicer and clearer. So I go back to writing the structs myself, including any needed comparision operators.
Since especially the operator<
can be quite cumbersome, I thought of circumventing this whole mess by just relying on the operations defined for tuple
:
Example of operator<
, e.g. for strict-weak-ordering:
bool operator<(MyStruct const& lhs, MyStruct const& rhs){
return std::tie(lhs.one_member, lhs.another, lhs.yet_more) <
std::tie(rhs.one_member, rhs.another, rhs.yet_more);
}
(tie
makes a tuple
of T&
references from the passed arguments.)
Edit: The suggestion from @DeadMG to privately inherit from tuple
isn't a bad one, but it got quite some drawbacks:
operator=
specifically) can be easily bypassedtie
solution, I can leave out certain members if they don't matter for the orderingAre there any drawbacks in this implementation that I need to consider?
This is certainly going to make it easier to write a correct operator than rolling it yourself. I'd say only consider a different approach if profiling shows the comparison operation to be a time-consuming part of your application. Otherwise the ease of maintaining this should outweigh any possible performance concerns.