Convert for loop to std::transform

Question

I have the following code:

for (auto it = _collection.cbegin(); it != _collection.cend(); ++it)
{
_values.emplace((*it)->Validate());
}

where:

std::vector<std::unique_ptr<MyObject>>  _collection;
std::unordered_map<std::string, MyOtherObject> _values;

and

CMyObject has a method:

virtual std::pair<std::string, MyOtherObject> Validate() = 0;

My question is: how can I use std::transform instead of for ? I can use lambda too, no pb.

Answer 1

I think that transform is not appropriate, but you can use for_each:

std::for_each( _collection.cbegin( ), _collection.cend( ), 
   [&]( const auto& obj ) { _values.emplace( obj->Validate( ) ); } );

or a for-each loop:

for( const auto& obj : _collection ) _values.emplace( obj->Validate( ) );

Answer 2

If you really want std::transform, I think this would work (not tested):

std::transform(_collection.cbegin(), _collection.cend(), std::inserter(_values, _values.end()),
  [](const std::unique_ptr<MyObject>& ptr) { return ptr->Validate(); });