Behaviors

Basics

Behaviors are a a way to define shared behavior. To indicate that an implementation does a certain behavior the does keyword is used. Implementations can do one or more behaviors.

If an implementation does a behavior then all the functions in the behavior must be implemented or there will be a compiler error. If an implementation does multiple behaviors with conflicting function names then there will be a compiler error. If a behavior and an impl have conflicting function names there will be a compiler error. These errors can be fixed by prefixing with BehaviorName:: to remove ambiguity. See example below.

As Types

Behaviors can be used as types for parameters to define a function that can take many types that all share that behavior.

Behaviors can be combined into new behviors via type intersections.

Type intersections can only be used with behaviors.

Conflicts

If two behaviors have conflicting symbols then the name of the bahavior must be used.

Default Implementations

Behaviors can have overridable default function implementations.

Printable Struct

To print a struct type use the fmt::Printable behavior.