Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is an older version of Boost and was released in 2023. The current version is 1.89.0.

Struct empty_env

Struct empty_env

boost::proto::empty_env — The type of an object that represents a transform environment with no key/value pairs in it.

Synopsis

// In header: <boost/proto/transform/env.hpp>


struct empty_env {

  // public member functions
  proto::key_not_found operator[](unspecified) const;
};

Description

`empty_env` public member functions

```
proto::key_not_found operator[](unspecified) const;
```
The type of the argument to this function has a user-defined implicit conversion from any type.