The Language Reference & Guide
- Welcome to Emojicode
- The Basics
- Variables and Assignment
- Control Flow
- Classes & Value Types
- Inheritance and Overriding
- Types and Namespaces
- Types as Values
- Safe and Unsafe Code
- Memory Management
- Appendix: The Emojicode Compiler
Protocols define methods for special functionality. Protocols only describe the methods a type must offer to support this functionality. Types can conform to protocols by implementing all methods and declaring the conformation.
Defining a protocol defines a type. All types that agree to that protocol are compatible to this type.
The syntax to define a protocol is simliar to the way of defining a class:
protocol ⟶ 🐊 type-identifier [generic-parameters] 🍇 protocol-body 🍉 protocol-body ⟶ protocol-method | protocol-method protocol-body protocol-method ⟶ [documentation-comment] [⚠️] mood emoji-id arguments return-type
🐊 💿 🍇 ❗️🎶 🍉
Here we declared a protocol named 💿. All classes that conform to this protocol will have to implement the method 🎶. This protocol doesn’t tell us anything about the actual type but we do know that all types that conform to 💿 are capable of playing music and therefore must provide the 🎶 method.
You can use the ❗️ to require instance methods inside the 🐊 body. At present it is not possible to require initializers or type methods.
To make a class conform to a protocol you must declare that it conforms to the protocol using the conformance syntax:
protocol-conformance ⟶ 🐊 type
Let us declare a class that conforms to 💿.
🐇 📱 🍇 🐊 💿 🆕 🍇🍉 ❗️ 🎶 🍇 😀 🔤Lalalala🔤❗️ 🍉 🍉
The actual statement to achieve this is
🐊 protocolName, where protocolName must be the type name of the protocol, and can occur everywhere in the class body.
Promises also apply when implementing protocol methods. An extension can also make a class conform to a protocol.
Calling Methods on Values of Protocol Type
Methods on protocol values are called like any other methods:
🖍🆕 cd_like 💿 🆕📱❗️ ➡️ 🖍 cd_like 🎶 cd_like❗️
It might happen that you’ll need to deal with values of types that implement several protocols. For instance, you might want to provide a method which requires an argument that can be accessed with 🐽️ and can be compared as defined by the 💿 protocol. This is where multiprotocols are of service.
You can use a multiprotocol type like so:
🍱 🐽️🐚🔡🍆 💿 🍱
For instance, when declaring the arguments to a method:
❗️ 🌈 a 🍱 🐽️🐚🔡🍆 💿 🍱 🍇 💭 ... 🍉
a can now be used both as an instance of a type conforming to 🐽️🐚🔡🍆 and as an insatnce of a type conforming to 💿.