mercredi 19 avril 2017

Using default template argument

This question is best asked by example. Say I want to declare a std::priority_queue with a comparator function. I could do:

auto cmp_fn = [](const std::string& left, const std::string& right) {
    return right < left;
};

std::priority_queue<std::string, std::vector<std::string>, decltype(cmp_fn)> queue(cmp_fn);

Is there any way to avoid specifying the middle template parameter so that the default is used? Something like

auto cmp_fn = [](const std::string& left, const std::string& right) {
    return right < left;
};

std::priority_queue<std::string, /* use default */, decltype(cmp_fn)> queue(cmp_fn);

Note: This is a simplified example of something more complicated I'm doing. Please don't answer with suggestion of the form: "just use std::greater". My question is about the template arguments.

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