Boost C++ Libraries: Ticket #9223: Alllow find(key) with key's type different from the contained value type.

attachment set

mjklaim@… — Thu, 10 Oct 2013 12:04:29 GMT

attachment → anyvalueset.hpp

Example of real-world code that would be simplified by the feature.

attachment set

mjklaim@… — Thu, 10 Oct 2013 12:05:06 GMT

attachment → anyvalueset.cpp

Test of the real world example.

mjklaim@… — Thu, 10 Oct 2013 12:09:28 GMT

As you will see in the example attached (tests uses Google Test) the call to find allow different types of keys than the underlying value type, as expressed in the "unique_key_values" test.

Unfortunately I had to write a custom "find" function in the AnyValueSet::SetOf class, so that the key is used to compare directly with the value, both types being preserved.

Fortunately, flat_set being basically a vector, it's not really a problem on performance to write the search this way.

Anyway, I wanted to give my use case. The find function could be simplified by just providing the key to flat_set instead of having to do the search manually.

Ion Gaztañaga — Sun, 13 Oct 2013 19:07:10 GMT

C++14 will include new find functions for associative containers:

template <class K> iterator find(const K& x); template <class K> const_iterator find(const K& x) const;

"returns an iterator pointing to an element with key r such that !c(r, ke) && !c(ke, r), or a_tran.end() if such an element is not found"

The original proposal was: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3657.htm

In the future, Boost.Container will try to implement C++14 features so I'll left this issue open until this feature is implemented.

status changed; resolution set

Ion Gaztañaga — Tue, 01 May 2018 13:23:29 GMT

status new → closed
resolution → fixed

Better late than never. Commit:

https://github.com/boostorg/container/commit/48c21e3187cd95b42803efe297842b52c896090e

Many thanks for the report.

mjklaim@… — Sun, 06 May 2018 20:58:15 GMT

Thanks for your work!