The short answer is that my marks a variable as private in a lexical scope, and local marks a variable as private in a dynamic scope. It’s easier to understand my, since that creates a local variable in the usual sense. There is a new variable created and it’s accessible only within the enclosing lexical … Read more
It all depends on context. :: is primarily necessary if there are namespace collisions, functions from different packages with the same name. When I load the dplyr package, it provides a function filter, which collides with (and masks) the filter function loaded by default in the stats package. So if I want to use the … Read more
As you probably have looked up the help page by now usage of :: helps to access the exact function from that specific package. When you load dplyr you probably got a message as follows.. The following objects are masked from ‘package:base’: intersect, setdiff, setequal, union So, for instance, if you would like to use … Read more
I realize there may be beginners looking to organize their code. This is 2022, and if you’re considering a modular JS app, you should get started with npm and Webpack right now. Here are a few simple steps to get started: In your project root, run npm init -y to initialize an npm project Download … Read more
<<- is most useful in conjunction with closures to maintain state. Here’s a section from a recent paper of mine: A closure is a function written by another function. Closures are so-called because they enclose the environment of the parent function, and can access all variables and parameters in that function. This is useful because … Read more
I understand them through examples. 🙂 First, lexical scope (also called static scope), in C-like syntax: void fun() { int x = 5; void fun2() { printf(“%d”, x); } } Every inner level can access its outer levels. There is another way, called dynamic scope used by the first implementation of Lisp, again in a … Read more
Function hoisting means that functions are moved to the top of their scope. That is, function b() { a = 10; return; function a() {} } will be rewritten by the interpeter to this function b() { function a() {} a = 10; return; } Weird, eh? Also, in this instance, function a() {} behaved … Read more