dart_scope_functions

dart_scope_functions is a Dart utility library that implements Kotlin-inspired scope functions. These functions provide a convenient way to execute a block of code within the context of an object, making the code more readable and expressive.

Features

• Execute blocks of code within the context of an object.
• Chain multiple operations on an object in a readable manner.
• Conditional operations on objects, including nullable types.

Installation

Add dart_scope_functions to your pubspec.yaml file:

dependencies:
  dart_scope_functions: latest

Then, run pub get to install the package.

Usage

Import the library:

import 'package:dart_scope_functions/dart_scope_functions.dart';

Example

void main() {
  var result = 'Hello'.also((it) {
    print(it); // Prints 'Hello'
  }).let((it) {
    return it.length;
  });

  print(result); // Prints 5

  var nullableString = null;
  var defaultString = nullableString.withDefault('Default Value');
  print(defaultString); // Prints 'Default Value'

  var conditionResult = 42.takeIf((it) => it > 40);
  print(conditionResult); // Prints 42

  var runResult = run(() {
    return 'Running a block';
  });
  print(runResult); // Prints 'Running a block'
}

API

Extensions on Any Type [T]

T also(void Function(T it) block)

Calls the specified function block with this value as its argument and returns this value.

• block: A function to execute with the value.
• Returns: The original value.

R let<R>(R Function(T it) block)

Calls the specified function block with this value as its argument and returns its result.

• block: A function to execute with the value.
• Returns: The result of block.

T? takeIf(bool Function(T it) predicament)

Returns this value if it satisfies the given predicament or null if it doesn't.

• predicament: A condition to evaluate.
• Returns: The value if it satisfies the condition, otherwise null.

T? takeUnless(bool Function(T it) predicament)

Returns this value if it does not satisfy the given predicament or null if it does.

• predicament: A condition to evaluate.
• Returns: The value if it does not satisfy the condition, otherwise null.

Extensions on Nullable Type [T?]

R letWithElse<R>(R Function(T it) block, {required R orElse})

Calls the specified function block with this value as its argument and returns its result. If this is null, it returns the provided orElse value.

• block: A function to execute with the value if it's not null.
• orElse: A default value to return if this is null.
• Returns: The result of block or orElse.

T withDefault(T defaultValue)

Returns this value if it's not null, otherwise returns the provided defaultValue.

• defaultValue: A default value to return if this is null.
• Returns: The value or the default value.

Global Functions

R run<R>(R Function() block)

Calls the specified function block and returns its result.

• block: A function to execute.
• Returns: The result of block.