I think we can make analogies with real world cases. PassthroughSubject = A doorbell push button When someone rings the door, you are notified only if you are at home (you are the subscriber) PassthroughSubject doesn’t have a state, it emits whatever it receives to its subscribers. CurrentValueSubject = A light switch Someone turns on … Read more
Your example of declarative programming above is not an actual program, so it’s not a good example. The main difference is between imperative and declarative. Functional is a particular kind of declarative. C, C++, Java, Javascript, BASIC, Python, Ruby, and most other programming languages are imperative. As a rule, if it has explicit loops (for, … Read more
Qt is developing QML, which looks a lot like XAML except in JSON. It’s available as a preview built against the current version, and is available in snapshots of the next version. Here’s a little snippet from http://doc.qt.nokia.com/4.7-snapshot/declarative-ui-components-progressbar.html import Qt 4.7 import “content” Rectangle { id: main width: 600; height: 405 color: “#edecec” Flickable { … Read more
Imperative There are several sub-paradigms of the imperative programming paradigm, such as the procedural or the object-oriented programming paradigms. In the imperative programming paradigm, you describe the algorithm step-by-step, at various degrees of abstraction. Examples of programming languages which support the procedural paradigm: C (and most other legacy languages) PHP, mostly In some sense, all … Read more
A great C# example of declarative vs. imperative programming is LINQ. With imperative programming, you tell the compiler what you want to happen, step by step. For example, let’s start with this collection, and choose the odd numbers: List<int> collection = new List<int> { 1, 2, 3, 4, 5 }; With imperative programming, we’d step … Read more