Lexical closures are functions, often anonymous, that capture, or close over, their lexical environment. Lexical closures are used extensively in functional programming techniques that involve higher-order functions.
Questions tagged [lexical-closures]
53 questions
106
votes
9 answers
Scope of lambda functions and their parameters?
I need a callback function that is almost exactly the same for a series of gui events. The function will behave slightly differently depending on which event has called it. Seems like a simple case to me, but I cannot figure out this weird behavior…
agartland
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- 2
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63
votes
7 answers
Do we have closures in C++?
I was reading about closures on the net. I was wondering if C++ has a built-in facility for closures or if there is any way we can implement closures in C++?
Parvinder Singh
- 1,737
- 2
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26
votes
1 answer
Getting arguments passed to an ES6 arrow function using arguments variable
I understand how arrow functions work in ES6, and the lexical this, but I was wondering if anyone knows of a way to get the arguments passed to an arrow function?
In ES5, you can simply do:
function foo( bar, baz ){
console.log('Args:',…
Justin
- 1,959
- 5
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- 40
15
votes
2 answers
Accessing VUE JS's data from Axios
I have a Vue JS (Vuetify) App that makes an ajax request that I would like to populate a div's content with the response, however I am having difficulties accessing the instance's data. All examples I have seen use this to point to the data object,…
Haddad
- 369
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- 9
8
votes
4 answers
javascript currying
I'm trying to create curry function that can be applied to any function and return another, with 1 of the arguments applied.
Properties that I want to have:
If function has only one argument curry function should return value:
f(a); curry(f,x) =…
qnikst
- 302
- 1
- 9
8
votes
2 answers
Prevent JavaScript closure from inheriting scope
I am looking for a fancy way to prevent a closure from inheriting surrounding scrope. For example:
let foo = function(t){
let x = 'y';
t.bar = function(){
console.log(x); // => 'y'
});
};
there are only two ways I know of preventing…
Alexander Mills
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- 817
8
votes
4 answers
Lexical scope/closures in javaScript
I understand functions in 'js' have lexical scope (i.e. functions create their environment (scope) when they are defined not when they are executed.)
function f1() {
var a = 1;
f2();
}
function f2() {
return a;
}
f1(); // a is not…
Antonio Pavicevac-Ortiz
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7
votes
1 answer
Using NSUndoManager, how to register undos using Swift closures
I am trying to grok how to use NSLayoutManager using Swift closures. I can successfully register an undo as follows:
doThing();
undoManager?.registerUndoWithTarget(self, handler: { _ in
undoThing();
}
undoManager?.setActionName("do thing")
Of…
wcochran
- 10,089
- 6
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7
votes
4 answers
Emacs lisp: why does this sexp cause an invalid-function error?
The sexp in question is
(((lambda (b)
(lambda (a)
(+ b a))) 3) 5)
which, to me, looks like it should evaluate to 8, and in other lisps (e.g. Racket) it does, but in elisp it instead throws this error:
Debugger entered--Lisp error:…
James Porter
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6
votes
2 answers
Recursive closure in JavaScript
function buildList( list ) {
var i = 0;
var first = function () {
console.log( "in" )
console.log( i );
}
var Second = function () {
console.log( "out" )
first();
}
return Second;
}
var a = buildList( [1, 2, 3]…
Parshuram Kalvikatte
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- 4
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- 40
6
votes
1 answer
What does "lexical" mean in the statement "C# implements lexical closure"?
I'm reading about C# and closure, various articles, Jon Skeet's awesome "C# in Depth" and I see statements like "C# and ruby implement lexical closure".
Why do the authors include the word "lexical"? Why not just say they "implement closure"?
What…
richard
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5
votes
1 answer
Lexical closures over macrolet?
Is there a way to do something like lexical closures using macrolet? What I want to do is make the following macro a local recursive helper that calls a function on each combination instead of generating a list as it does now calling the macro in…
asm
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5
votes
2 answers
Clojure closure efficiency?
Quite often, I swap! an atom value using an anonymous function that uses one or more external values in calculating the new value. There are two ways to do this, one with what I understand is a closure and one not, and my question is which is the…
Chris Tennant
- 190
- 8
4
votes
4 answers
How does the JS scope of these blocks work?
Can anyone explain why the following produces 1,2 and the other produces 5? Should they not both produce 5?
//produces 1,2
(function () {
var a = [5];
function bar() {
if (!a) {
var a = [1, 2];
}
…
Harvester316
- 381
- 1
- 8
- 17
4
votes
1 answer
Closures get parent function name
Bash is “kind of function programming language” it dose not have classes. I
managed to use encapsulation with Closures, but I want also to do some
introspection to find also docker_ parent/super/base function (If you know add
comments to define this…
Andrei.Danciuc
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- 10
- 24