builder-macro

import BuilderMacro

@Builder
struct Person {
    let id: UUID
    let name: String
    let bday: Date
}

// Expanded

struct Person {
    let firstName: String, let lastName: String, let middleName: String
    let birthday: Date
    let city: String

    struct PersonBuilder {
        var firstName: String?
        var lastName: String?
        var middleName: String?
        var birthday: Date?
        var city: String?

        func firstName(_ firstName: String) -> Self {
            var copy = self
            copy.firstName = firstName
            return copy
        }

        func lastName(_ lastName: String) -> Self {
            var copy = self
            copy.lastName = lastName
            return copy
        }

        func middleName(_ middleName: String) -> Self {
            var copy = self
            copy.middleName = middleName
            return copy
        }

        func birthday(_ birthday: Date) -> Self {
            var copy = self
            copy.birthday = birthday
            return copy
        }

        func city(_ city: String) -> Self {
            var copy = self
            copy.city = city
            return copy
        }

        enum BuildError: Swift.Error {
            case missingRequiredField(description: String)
        }

        func build() throws -> Person {
            guard let firstName = firstName else {
                throw BuildError.missingRequiredField(description: "firstName")
            }

            guard let lastName = lastName else {
                throw BuildError.missingRequiredField(description: "lastName")
            }

            guard let middleName = middleName else {
                throw BuildError.missingRequiredField(description: "middleName")
            }

            guard let birthday = birthday else {
                throw BuildError.missingRequiredField(description: "birthday")
            }

            guard let city = city else {
                throw BuildError.missingRequiredField(description: "city")
            }

            return Person(
                firstName: firstName,
                lastName: lastName,
                middleName: middleName,
                birthday: birthday,
                city: city
            )
        }
    }
}

import BuilderMacro

@Builder(addGuards: true)
struct Person {
    let id: UUID
    let name: String
    let bday: Date
}

dependencies: [
    .package(url: "https://github.com/space-code/builder-macro.git", .upToNextMajor(from: "1.0.0"))
]