Typed Parameters

In OSL, you can specify the expected type of a function parameter to improve code clarity and enable better error checking. This feature allows you to declare what type of data a function expects, making your code more robust and self-documenting.

Syntax

def functionName(type paramName) (
  // function body
)

Supported Types

You can use any of the following types for parameter type annotations:

• string - Text values

• number - Numeric values (integers and decimals)

• boolean - Logical values (true/false)

• array - JSON arrays

• object - JSON objects

• function - Function objects

• any - Any type (default if no type is specified)

Examples

Basic Type Annotations

// Function with a number parameter
def double(number val) (
  return val * 2
)

// Function with a string parameter
def greet(string name) (
  return "Hello, " ++ name ++ "!"
)

// Function with multiple typed parameters
def createPerson(string name, number age) (
  return {
    name: name,
    age: age
  }
)

Using Type Annotations for Validation

When you specify a type for a parameter, OSL will automatically validate that the provided argument matches the expected type. If an incorrect type is provided, an error will be thrown.

def double(number val) (
  return val * 2
)

log double(10)    // Works correctly, outputs: 20
log double("10")  // Error: Expected number but got string

Complex Type Annotations

You can also use type annotations with more complex function signatures:

// Function that takes a callback function
def processData(array data, function processor) (
  result = []
  for i data.len (
    result = result.append(processor(data[i]))
  )
  return result
)

// Using the function
numbers = [1, 2, 3, 4, 5]
log processData(numbers, double)  // Outputs: [2, 4, 6, 8, 10]

Benefits of Typed Parameters

1. Self-documenting code - Type annotations make it clear what kind of data a function expects

2. Early error detection - Type mismatches are caught when the function is called

3. Better IDE support - Enables better code completion and hints

4. Improved maintainability - Makes code easier to understand and modify

Notes

• Type annotations are optional - you can mix typed and untyped parameters

• If no type is specified, the parameter accepts any type

• Type checking happens at runtime when the function is called

• Type annotations do not affect the function's return value