CODEWITHSUNDEEP
c++c++11stltuples
gsamaras
gsamaras

Reputation: 73366

Can't initialize std::tuple as std::pair?

From my previous question about std::pair, I thought I would be able to do something like the following, but it won't compile.

typedef Point::FT float; 
std::vector<std::tuple<Point::FT, int, int> > branch{ (int)(max_leaf_check * mul_factor),
  { std::numeric_limits<Point::FT>::max(), -1 , -1} };

Error:

error: converting to ‘const value_type {aka const std::tuple<float, int, int>}’ from initializer list would use explicit constructor ‘std::tuple< <template-parameter-1-1> >::tuple(_UElements&& ...) [with _UElements = {float, int, int}, <template-parameter-2-2> = void, _Elements = {float, int, int}]’

How do I fix it? If it can't be fixed, is there any other way to do the initialization in one line?

As a follow up, I can't even make it work with push_back().

Point::FT new_dist;
size_t other_child_i, tree_i;
branch.push_back({new_dist, other_child_i, tree_i});

Similar error.

Upvotes: 2

Views: 300

Answers (1)

Mike Seymour
Mike Seymour

Reputation: 254431

How do I fix it?

You can't; the explicit constructor prevents implicit brace-initialisation.

If it can't be fixed, is there any other way to do the initialization in one line?

std::make_tuple(std::numeric_limits<Point::FT>::max(), -1 , -1)

As a follow up, I can't even make it work with push_back().

branch.emplace_back(new_dist, other_child_i, tree_i);

Upvotes: 4

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