Thread: add subscription operator if the value provide it.

[mjklaim@…]

I would like to be able to do

    typedef boost::synchronized_value< boost::container::flat_map<int, int> > ValueIndex;
    
    ValueIndex index;
    index[0] = 1;

and would expect that last line to be equivalent to

    auto locked_index = index.synchronize();
    (*locked_index)[0] = 1;

I'm not totally sure it's possible to do but it would help.

[viboes]

The statement

index[0] = 1;

concerns two operations, the operator[] which returns a reference and the assignment operator.

In order to make this work we will need to use expression templates

operator[] would return a proxy reference, let call it at_type, that must store a reference to the synchronized_value instance and the index.

We would need to overload the assignment operator on at_type so that it can do what you want as an atomic operation.

I have not too much time to implement this kind of cosmetic features, but a patch would be welcome. Do you think that you can do it?

[mjklaim@…]

I started to consider how to do it at the time I wrote this but right now I'm overloaded with work. I'll try a patch asap but not immediately.