You are basically creating a closure. In computer science, a closure is a first-class function with free variables that are bound in the lexical environment. Such a function is said to be “closed over” its free variables. Related reading: Closures: why are they so useful? A closure is simply a more convenient way to give … Read more
Compare this, without using nonlocal: x = 0 def outer(): x = 1 def inner(): x = 2 print(“inner:”, x) inner() print(“outer:”, x) outer() print(“global:”, x) # inner: 2 # outer: 1 # global: 0 To this, using nonlocal, where inner()‘s x is now also outer()‘s x: x = 0 def outer(): x = 1 … Read more
Nested functions really don’t do anything that you can’t do with non-nested ones (which is why neither C nor C++ provide them). You say you are not interested in other compilers – well this may be atrue at this moment, but who knows what the future will bring? I would avoid them, along with all … Read more
>>> def sum(x, y): … def do_it(): … return x + y … return do_it … >>> a = sum(1, 3) >>> a <function do_it at 0xb772b304> >>> a() 4 Is this what you were looking for? It’s called a closure.
You are understanding it correctly. You cannot use x to assign to in a nested scope in Python 2. In Python 3, you can still use it as a binding occurrence by marking the variable as nonlocal; this is a keyword introduced for just this usecase: def f(x): def g(n): nonlocal x if n < … Read more
GCC uses something called a trampoline. Information: http://gcc.gnu.org/onlinedocs/gccint/Trampolines.html A trampoline is a piece of code that GCC creates in the stack to use when you need a pointer to a nested function. In your code, the trampoline is necessary because you pass g as a parameter to a function call. A trampoline initializes some registers … Read more
Normally you do it to make closures: def make_adder(x): def add(y): return x + y return add plus5 = make_adder(5) print(plus5(12)) # prints 17 Inner functions can access variables from the enclosing scope (in this case, the local variable x). If you’re not accessing any variables from the enclosing scope, they’re really just ordinary functions … Read more
If you are using PHP 5.3 you can get more JavaScript-like behaviour with an anonymous function: <?php function outer() { $inner=function() { echo “test\n”; }; $inner(); } outer(); outer(); inner(); //PHP Fatal error: Call to undefined function inner() $inner(); //PHP Fatal error: Function name must be a string ?> Output: test test
function initValidation() { // irrelevant code here function validate(_block){ console.log( “test”, _block ); } initValidation.validate = validate; } initValidation(); initValidation.validate( “hello” ); //test hello
Functions are another type of variable in JavaScript (with some nuances of course). Creating a function within another function changes the scope of the function in the same way it would change the scope of a variable. This is especially important for use with closures to reduce total global namespace pollution. The functions defined within … Read more