Issue #64: Remove explicit bind/unbind interface.

* Remove bind() and unbind() functions and the associated wording.

Author: Gordon

affinity/cpp-20/d0796r3.md

@@ -303,10 +303,6 @@ If a particular policy or algorithm requires to access placement information, th
 
 The `execution_resource` which underlies the current thread of execution can be queried through `this_thread::get_resource`.
 
-### Binding to execution
-
-A *thread of execution* can be requested to bind to a particular `execution_resource` for a particular *execution agent* by calling `this_thread::bind` if that `execution_resource` is able to place agents. If the current *thread of execution* is successfully bound to the specified `execution_resource` it will return `true` otherwise it will return `false`. If the *thread of execution* is successfully bound to the specified `execution_resource` then `execution_resource` returned by `this_thread::get_resource` must be equal to the `execution_resource` provided to `this_thread::bind`. Subsequently a *thread of execution* can be unbound by calling `this_thread::unbind`.
-
 > [*Note:* Binding *threads of execution* can provide performance benefits when used in a way which compliments the application, however incorrect usage can lead to denial of service and therefore can cause loss of performance. *--end note*]
 
 ## Header `<execution>` synopsis
@@ -410,9 +406,6 @@ A *thread of execution* can be requested to bind to a particular `execution_reso
 
     namespace this_thread {
       std::experimental::execution::execution_resource get_resource() noexcept;
-
-      bool bind(execution_resource eR) noexcept;
-      bool unbind(execution_resource eR) noexcept;
     }
 
     }  // experimental
@@ -601,26 +594,6 @@ The free function `this_system::get_resources` is provided for retrieving the `e
 
 > [*Note:* Returning a `std::vector` allows users to potentially manipulate the container of `execution_resource`s after it is returned. We may want to replace this at a later date with an alternative type which is more restrictive, such as a range or span. *--end note*]
 
-### `this_thread::bind` & `this_thread::unbind`
-
-The free functions `this_thread::bind` and `this_thread::unbind` are provided for binding / unbinding the current *thread of execution* to / from a particular `execution_resource`.
-
-    bool bind(execution_resource eR) noexcept;
-
-*Returns:* `true` if the requested binding was successful, otherwise `false`.
-
-*Requires:* `eR.can_place_agents() == true`.
-
-*Effects:* If successful, binds the current *thread of execution* to the specified `execution_resource`.
-
-    bool unbind(execution_resource eR) noexcept;
-
-*Returns:* `true` if the requested unbinding was successful, otherwise `false`.
-
-*Requires:* `eR.can_place_agents() == true`.
-
-*Effects:* If successful, unbinds the current *thread of execution* from the specified `execution_resource`.
-
 ### `this_thread::get_resource`
 
 The free function `this_thread::get_resource` is provided for retrieving the `execution_resource` underlying the current thread of execution.