anonymous-function

问题 I'm looking at section 13 or the ECMAScript specification (v. 5). An anonymous function expression is initialized as follows: Return the result of creating a new Function object as specified in 13.2 with parameters specified by FormalParameterListopt and body specified by FunctionBody. Pass in the LexicalEnvironment of the running execution context as the Scope. Pass in true as the Strict flag if the FunctionExpression is contained in strict code or if its FunctionBody is strict code. this

问题 Is there any kind of performance or other difference between following two cases of accessing a global variable in a closure: Case 1: $closure = function() use ($global_variable) { // Use $global_variable to do something. } Case 2: $closure = function() { global $global_variable; // Use $global_variable to do something. } 回答1: There is an important difference between your two examples: $global_variable = 1; $closure = function() use ($global_variable) { return $global_variable; }; $closure2 =

问题 I have a follow-up question to the one discussed here: Laravel core method confusion I am in the same situation as driechel (author of question above) has been before, currently getting used to Laravel 4 FW and examining the core. Although a precise answer has been given I still don't understand the logic and what is happening under the hood. So I would very much appreciate a further explanation. I know this might be a duplicate but since I cannot post comments yet I'll give it a shot with a

问题 I am trying to use the function signal(int,void(*)(int)) from <csignal> to handle the floating point exception SIGFPE. I'd like to be able to print some useful diagnostics besides just a message saying "Floating point exception" or something to that effect. This means the function I pass as the handler to signal needs access to some of the data in my code. Therein lies the rub. The function must return void and accept only 1 parameter of type int . I cannot make the handler a member function

问题 I'm trying to use array_walk with an anonymous function, but I always get the error // Parse error: syntax error, unexpected T_FUNCTION in ... on line X if(!empty($myArray)) { array_walk($myArray, function(&$value, $key){ // Line X $value = '"'.$value.'"'; // Add quotes }); } The surrounding file syntax is correct. Any thoughts? 回答1: Yes, true anonymous functions (closures) are only available from PHP 5.3, however you can still create an anonymous function in earlier versions of PHP using the

问题 The question is based on a design pattern solution easily doable in other languages but difficult to implement in C. The narrowed down code is below. Building on this answer, I'm trying to find a solution for the dynamically generated values in an anonymous function. Excerpt from the answer: int (*max)(int, int) = ({ int __fn__ (int x, int y) { return x > y ? x : y; } __fn__; }); Static Library Code struct Super{ } void add(struct Super *(*superRef)()) { // cache the reference (in some linked

问题 I'm trying to dump elements of an object's private property through an anonymous function - of course I could achieve this in any number of other ways, but this highlights a PHP conundrum I can't solve off the top of my head, short of $foo = $this and using $foo - but THAT won't give me the private stuff, so... suggestions ? Sample code: class MyClass { private $payload = Array( 'a' => 'A element', 'b' => 'B element'); static $csvOrder = Array('b','a'); public function toCSV(){ $values =

问题 For some reason, the event listener is firing twice for each element when passing arguments into an anonymous function. I.e., the click event on element el will register once and, thus, fire once. el.addEventListener("click", handle, false); el.addEventListener("click", handle, false); But if I want to pass my own arguments to it, it will register and fire twice. el.addEventListener("click", function() { handle(event, myArgument); }, false); el.addEventListener("click", function() { handle

问题 This has got me very confused and I can't seem to find an answer to this question. A clear and simple clarification would be nice. 回答1: A closure is a function that is evaluated in its own environment, which has one or more bound variables that can be accessed when the function is called. They come from the functional programming world, where there are a number of concepts in play. Closures are like lambda functions, but smarter in the sense that they have the ability to interact with

问题 I was pretty excited to read about anonymous functions in php, which let you declare a variable that is function easier than you could do with create_function. Now I am wondering if I have a function that is passed a variable, how can I check it to determine if it is a function? There is no is_function() function yet, and when I do a var_dump of a variable that is a function:: $func = function(){ echo 'asdf'; }; var_dump($func); I get this: object(Closure)#8 (0) { } Any thoughts on how to