go / intermediate
Snippet
Custom Function Types for Strategy Pattern
Functions in Go are first-class citizens. You can define custom function types, which is useful for implementing patterns like Strategy or Middleware, allowing behavior to be passed as arguments.
snippet.go
go
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package mainimport "fmt"type Validator func(string) boolfunc IsEmail(s string) bool {return len(s) > 3 // Simplified logic}func ValidateInput(input string, v Validator) {if v(input) {fmt.Println("Input is valid")} else {fmt.Println("Input is invalid")}}func main() {ValidateInput("", func(s string) bool {return len(s) > 0})}
Breakdown
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type Validator func(string) bool
Defines a new type 'Validator' that represents any function taking a string and returning a bool.
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func ValidateInput(input string, v Validator)
A function that accepts a Validator type as a parameter.
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func(s string) bool { ... }
Passes an anonymous function (closure) that matches the Validator signature.