Examples how to use closures

100%

Examples how to use closures

✓ Published0🌍 Public

Last edited Apr 22, 2018

Created on Apr 22, 2018

This example shows two ways to define and call functions that accept closures in Swift. The first passes an inline closure that takes an integer and returns a string, producing a computed result. The second uses an escaping closure that returns a `UIViewController`, demonstrating how to instantiate a view controller lazily. The code relies on Swift’s closure syntax and the UIKit `UIViewController` class, with the second closure marked `@escaping` to allow storage beyond the function call.

AI-generated description

Similar vizzes

Loading thumbnail…

Swift protocol and extensions for adding support to closures in UIKit classes. Extension support for UIButton, UIGestureRecognizer, UIBarButtonItem etc. Swift 3.0.

This example demonstrates a Swift protocol that adds closure-based event handling to UIKit classes, replacing traditional target-action patterns. Code extensions for UIButton, UIPageControl, UIGestureRecognizer, and UIBarButtonItem use the Closurable protocol to wrap callbacks in a ClosureContainer object, stored via objc_setAssociatedObject. The container exposes an @objc selector that invokes the stored closure, allowing UIKit to call the handler dynamically. The code pairs each UI component’s standard addTarget or initializer with custom convenience methods, keeping the call site concise. No external libraries are required; the implementation relies solely on Swift 3.0 and the Objective-C runtime.

MMoximillian

65% match

Loading thumbnail…

Example of a closure function in Power Query

This example shows a closure function in Power Query, where a nested function returns another function that captures and returns a value. The code defines a `ring` function that, when called, produces another function; invoking the first call returns the inner function, and the second call retrieves the `Answer` record. It demonstrates the mechanics of closure and deferred execution, using Power Query’s `let` and `in` syntax. The data source is a hardcoded record, and the rendering is not applicable, as the output is a text result.

HHugoberry

56% match

Loading thumbnail…

[Power Query] [m] Closures

This example visualizes the inner workings of a TypeScript-based function-closure mechanism, showing how parameter lists are programmatically overwritten and restricted. It demonstrates the step-by-step process of copying a function (`fnCopy`) and applying `setParameters` to limit its arguments to a specific range, then wrapping that operation with another `setParameters` call to further constrain the allowed parameter indices to 1–9. The code uses TypeScript’s type system and higher-order functions (like `setParameters`) to manipulate closures at runtime. The rendering approach is textual, highlighting the sequential logic through code snippets, with no graphical or data-driven output beyond the functional transformation.

HHugoberry

52% match

Loading thumbnail…

[Power Query] Closures, partial application and cascading parameters

This example demonstrates how Power Query’s M language implements closures and partial application through nested functions. The code defines `addTo` as a function that returns another function, capturing the outer variable `x`. By calling `addTo(5)`, it creates `addToFive`, a closure that retains the value 5 in its scope. When `addToFive(3)` is invoked, the closure evaluates to 8, showing how cascading parameters flow through each layer. The rendering is purely textual, with no external libraries or data sources; the logic itself is the visualization.

HHugoberry

51% match

Loading thumbnail…

Example of how init/func behaves in protocols and protocol extensions

This example demonstrates how Swift handles `init` and `func` declarations in protocols versus protocol extensions. It defines two similar protocol pairs—one where `P1` declares both members, and another where `P2` is empty and relies entirely on its extension—to show that a struct’s own implementations always take precedence over those in the extension. The code creates instances of `S1` and `S2` and calls their methods, printing "S1 init"/"S1 func" and "S2 init"/"S2 func" respectively, proving that the extension’s fallback implementations are never invoked when the struct provides its own.

MMoximillian

51% match

Loading thumbnail…

[Power Query] Closures, partial application and cascading parameters

This example shows how Power Query applies functional techniques to build a cascading parameter system, where a selection in one step narrows the choices in the next. It demonstrates closures and partial application by defining a function `fn.ts` that takes an initial parameter `x` and returns a second function awaiting `y`, ultimately computing their product. The visualization uses this pattern to drive linked dropdowns or sliders, where the output of one control feeds directly into the next. The code relies on Power Query’s native M language functions for data shaping, with no external libraries, and the rendering approach is not specified in the provided snippet.

HHugoberry

49% match

Loading thumbnail…

An eventing mechanism for Swift

This example demonstrates an eventing mechanism for Swift, showing how to create type-safe events with multiple handlers and automatic cleanup. It defines an `Event<T>` class that manages a collection of handler wrappers, allowing observers to subscribe and unsubscribe dynamically. The implementation uses the `Disposable` protocol for tear-down logic and the `Invocable` private protocol to abstract handler invocation, with `EventHandlerWrapper` holding a weak reference to the target to prevent retain cycles. The code highlights Swift’s protocol-oriented and generics features, as well as curried instance methods, to build a reusable notification system without relying on external libraries.

CColinEberhardt

49% match

Loading thumbnail…

Journey into PAT-land

This example shows a programmer’s repeated attempts to create a unified interface for dequeuing reusable cells across UITableView and UICollectionView in Swift, using protocols with associated types and generics. The code illustrates the progression from a simple protocol that fails to preserve type information, through generic and PAT-based approaches, to a final multiprotocol solution incorporating a parent protocol and Self-typed static methods. It highlights the Swift compiler’s constraints, such as lack of parametrized extensions and existential casting limitations, while referencing ProtoKit, UITableView, UICollectionView, and IndexPath.

MMoximillian

48% match