6. Closures
Closures are a powerful feature in Magnolia Groovy Script, and they can be used in various ways. Let's go through some important use cases with examples:
Basic Closure
A closure is a block of code that can be assigned to a variable and executed later. Here's a basic example of a closure in Magnolia Groovy Script:
def sayHello = {
println("Hello, Magnolia!")
}
// Execute the closure
sayHello()Closure with Parameters
Closures can take parameters just like regular functions:
def greet = { name ->
println("Hello, $name!")
}
// Execute the closure with a parameter
greet("Magnolia")
[Tip: Use the -> symbol to specify parameters in the closure.]
Closures as Arguments
You can pass closures as arguments to other functions. For example, you can use the each method on a list:
def numbers = [1, 2, 3, 4, 5]
numbers.each { num ->
println("Number: $num")
}[Tip: Closures are often used for concise and expressive code when working with collections.]
Returning Closures
Closures can also be returned from functions. Here's an example where a function returns a closure:
def createMultiplier = { factor ->
return { value ->
value * factor
}
}
def doubleInput = createMultiplier(2)
println(doubleInput(5)) // Output: 10[Tip: Returning closures can be useful for creating specialized functions on the fly.]
Closures with External Variables
Closures can capture external variables. This is called closure scoping:
def createCounter = {
def count = 0
return {
count++
}
}
def counter = createCounter()
println(counter()) // Output: 0
println(counter()) // Output: 1[Tip: Closures can access variables from their enclosing scope even after the enclosing function has completed.]
Closure Composition
You can compose closures to create more complex behavior:
def add = { x, y -> x + y }
def multiply = { x, y -> x * y }
def calculate = { operation, x, y ->
operation(x, y)
}
println(calculate(add, 3, 2)) // Output: 5
println(calculate(multiply, 3, 2)) // Output: 6[Tip: Closure composition allows for flexible and reusable code.]
Contact the author
