tutorial10

Generics in GO

Key Concepts

Generics

Generics is a concept in programming where a function or a data type can be written in a way that it can handle different data types. In Go, generics are defined using square brackets [] followed by a type parameter list.

Generic Functions

In this program, we have three generic functions: sumSlice, isEmpty, and LoadJSON.

func sumSlice[T int | float32 | float64](slice []T) T{
    var sum T
    for _, v := range slice{
        sum += v
    }
    return sum
}

func isEmpty[T any](slice []T) bool{
    return len(slice) == 0
}

func LoadJSON[T contactInfo | purchaseInfo] (filePath string) []T{
    data, _ := ioutil.ReadFile(filePath)    
    var loaded = []T{}  
    json.Unmarshal(data, &loaded)

    return  loaded
}

sumSlice takes a slice of type T where T can be int, float32, or float64. It returns the sum of all elements in the slice.

isEmpty takes a slice of any type T and returns a boolean indicating whether the slice is empty.

LoadJSON takes a file path as input and returns a slice of type T where T can be contactInfo or purchaseInfo. It reads the JSON file from the given file path and unmarshals the data into a slice of the appropriate type.

Generic Structs

In this program, we have two struct types: contactInfo and purchaseInfo.

type contactInfo struct{
    Name string 
    Email string    
}
    
type purchaseInfo struct{   
    Name string
    Price float32
    Amount int
}

These structs are used as type parameters in the LoadJSON function to load JSON data of different types.

Usage

In the main function, we demonstrate the usage of these generic functions.

func main(){
    var intSlice = []int{1,2,3}
    fmt.Println(sumSlice[int](intSlice))

    var float32Slice = []float32{1,2,3}
    fmt.Println(sumSlice[float32](float32Slice))

    var sliceint = []int{}
    fmt.Println(isEmpty[int](sliceint))
    fmt.Println(isEmpty[int](intSlice))

    var contacts []contactInfo = LoadJSON[contactInfo]("./files/contactInfo.json")
    fmt.Printf("\n%+v", contacts)

    var purchases []purchaseInfo = LoadJSON [purchaseInfo]("./files/PurchaseInfo.json")
    fmt.Printf("\n%+v", purchases)
}

We create slices of int and float32 and use sumSlice to calculate their sums. We also check if a slice is empty using isEmpty. Finally, we use LoadJSON to load JSON data into slices of contactInfo and purchaseInfo.

Checkout the code

• main.go