db::protocols::Mutator Struct Reference

A DataBox mutator. More...

#include <Mutator.hpp>

Classes
struct	test

Detailed Description

A DataBox mutator.

A class conforming to this protocol can be used as the template argument for a call to db::mutate_apply(const gsl::not_null<DataBox<BoxTags>*> box, Args&&... args). The conforming class must provide the following:

• return_tags: A type list of tags corresponding to mutable items in the DataBox passed to db::mutate_apply that may be modified.
• argument_tags: A type list of tags corresponding to items in the DataBox passed to db::mutate_apply that may not be modified.

• apply: A static function whose return value is returned by db::mutate_apply, and that takes as arguments:

  • A const gsl::not_null<Tag::type*> for each Tag in return_tags
  • A const db::const_item_type<Tag, BoxTags> for each Tag in argument_tags
  • The additional arguments passed to db::mutate_apply

  Note: use the explicit type whenever possible, not the type aliases. db::const_item_type will usually be Tag::type unless that is a std::unique_ptr<T>, in which case it will be T

Here is an example for a class conforming to this protocol:

struct ExampleMutator : tt::ConformsTo<db::protocols::Mutator> {
  using return_tags = tmpl::list<ExampleSimpleTag0, ExampleSimpleTag1>;
  using argument_tags = tmpl::list<ExampleSimpleTag2>;
 
  static void apply(const gsl::not_null<double*> item_0,
                    const gsl::not_null<int*> item_1, const double item_2,
                    const int additional_arg) {
    *item_0 = 2.0 * item_2;
    *item_1 = 2 * additional_arg;
  }
};

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The documentation for this struct was generated from the following file:

• src/DataStructures/DataBox/Protocols/Mutator.hpp