I use anonymous functions for three reasons: If no name is needed because the function is only ever called in one place, then why add a name to whatever namespace you’re in. Anonymous functions are declared inline and inline functions have advantages in that they can access variables in the parent scopes. Yes, you can … Read more
When the keyword function is met in a statement position (as the first token in a statement), the function declaration is expressed as a function statement. Function statements are hoisted to the top of the scope, cannot be immediately invoked and must have a name. When the keyword is met in an expression position (i.e. … Read more
Use a = sorted(a, key=lambda x: x.modified, reverse=True) # ^^^^ On Python 2.x, the sorted function takes its arguments in this order: sorted(iterable, cmp=None, key=None, reverse=False) so without the key=, the function you pass in will be considered a cmp function which takes 2 arguments.
Simple rules to determine the scope of underscore: If the underscore is an argument to a method, then the scope will be outside that method, otherwise respective the rules below; If the underscore is inside an expression delimited by () or {}, the innermost such delimiter that contains the underscore will be used; All other … Read more
Pre Java 8: The closest Java has to delegates are single method interfaces. You could use an anonymous inner class. interface StringFunc { String func(String s); } void doSomething(StringFunc funk) { System.out.println(funk.func(“whatever”)); } doSomething(new StringFunc() { public String func(String s) { return s + “asd”; } }); doSomething(new StringFunc() { public String func(String s) { … Read more
Inside of your anonymous function this is the global object. Inside of test, this is the instance of MyObject on which the method was invoked. Whenever you call a function like this: someFunction(); // called function invocation this is always the global object, or undefined in strict mode (unless someFunction was created with bind** — … Read more
You can use the use keyword to inherit variables from the parent scope. In your example, you could do the following: $callback = function($val) use ($avg) { return $val < $avg; }; For more information, see the manual page on anonymous functions. If you’re running PHP 7.4 or later, arrow functions can be used. Arrow … Read more
Anonymous functions are useful when using functions that require a callback function like array_filter or array_map do: $arr = range(0, 10); $arr_even = array_filter($arr, function($val) { return $val % 2 == 0; }); $arr_square = array_map(function($val) { return $val * $val; }, $arr); Otherwise you would need to define a function that you possibly only … Read more
In PHP, methods and properties are in a separate namespace (you can have a method and a property with the same name), and whether you are accessing a property or a method depends of the syntax you are using to do so. $expr->something() is a method call, so PHP will search something in the class’ … Read more