C++ std::map equivalent? (An in-order iterable associative container)

[Dicebot via Digitalmars-d-learn]

On Sunday, 4 May 2014 at 21:40:04 UTC, bearophile wrote:
> Mark Isaacson:
>
>> 2) Create a wrapper struct that contains key and value and 
>> whose comparison operator is defined only on the key. This 
>> would essentially be doing what the C++ implementation does.
>
> Until we have a tree-based associative map, use a tuple for the 
> key-value and define a "less" template argument like q{a.key < 
> b.key} or q{a[0] < b[0]}.
>
> Bye,
> bearophile

What benefits this gives over definining distinct struct? Sounds 
like unnecessary complication for me.