Enums in Solidity are user-defined types that represent a set of named values. They provide a way to define a limited number of options or states that a variable can take. 🌈 Each option is assigned an implicit ordinal value, starting from zero for the first option and incrementing by one for each subsequent option. Enums are useful when you want to represent a finite set of choices or track the state of an object with a limited number of possible values.
To declare an enum in Solidity, you use the enum keyword followed by the name of the enum and a list of its possible values enclosed in curly braces. Let’s take a look at an example: 🖋️
enum Status {Pending, Shipped, Accepted, Rejected, Canceled }
In this example, we have defined an enum called Status with five possible values: Pending, Shipped, Accepted, Rejected, and Canceled. 📋 By default, the first value listed in the enum definition (Pending in this case) is assigned the ordinal value of zero. Subsequent values are assigned ordinal values in increasing order.
Enums can be used as data types for variables and function parameters in Solidity contracts. Let’s create a contract called Enum to demonstrate how enums can be utilized: 🏗️
contract Enum {
enum Status {
Pending,
Shipped,
Accepted,
Rejected,
Canceled
}
Status public status;
function get() public view returns (Status) {
return status;
}
function set(Status _status) public {
status = _status;
}
function cancel() public {
status = Status.Canceled;
}
function reset() public {
delete status;
}
}
Now, let’s analyze and discuss the different parts of the Enum contract and how enums are utilized:
1️⃣ Enum Declaration:
The Status enum represents the shipping status of an item and has five possible values: Pending, Shipped, Accepted, Rejected, and Canceled. 📦
2️⃣ Status Variable:
The status variable of type Status is declared as public, allowing external access. This variable holds the current shipping status of an item. 📮
3️⃣ Getter Function (get):
The get function is a public view function that returns the current value of the status variable. It allows external entities to read the shipping status without modifying it. 🔍
4️⃣ Setter Function (set):