If a class member is always initialized with the same initial value, then you should make the initializer inline, so as to avoid duplication. If the initial value depends on the constructor, then put it in the constructor initializer list. (And never use assignment in the way you did.) Example: class Foo { bool done … Read more
You can’t create compile-time constants of object references. The only valid compile-time constant you can use is null, so change your code to this: public void DoSomething(int index, ushort[] array = null, bool thirdParam = true) And inside your method do this: array = array ?? new ushort[0]; (from comments) From C# 8 onwards you … Read more
Your post is correct. Unfortunately, if you need to use an optional parameter at the very end of the parameter list, you have to specify everything up until that last parameter. Generally if you want to mix-and-match, you give them default values of ” or null, and don’t use them inside the function if they … Read more
In the Python spirit of “ask for forgiveness, not permission”, here’s one way: try: b = a[4] except IndexError: b = ‘sss’
You can do it for a const reference, but not for a non-const one. This is because C++ does not allow a temporary (the default value in this case) to be bound to non-const reference. One way round this would be to use an actual instance as the default: static int AVAL = 1; void … Read more
A function can have multiple signatures if the signatures differ in arity. You can use that to supply default values. (defn string->integer ([s] (string->integer s 10)) ([s base] (Integer/parseInt s base))) Note that assuming false and nil are both considered non-values, (if (nil? base) 10 base) could be shortened to (if base base 10), or … Read more
You can work around this very easily by changing your signature. void Foo(TimeSpan? span = null) { if (span == null) { span = TimeSpan.FromSeconds(2); } … } I should elaborate – the reason those expressions in your example are not compile-time constants is because at compile time, the compiler can’t simply execute TimeSpan.FromSeconds(2.0) and … Read more
Use the =? flag for the property in the scope block of the directive. angular.module(‘myApp’,[]) .directive(‘myDirective’, function(){ return { template: ‘hello {{name}}’, scope: { // use the =? to denote the property as optional name: ‘=?’ }, controller: function($scope){ // check if it was defined. If not – set a default $scope.name = angular.isDefined($scope.name) ? … Read more
Mutable default arguments don’t generally do what you want. Instead, try this: class Node: def __init__(self, wordList=None, adjacencyList=None): if wordList is None: self.wordList = [] else: self.wordList = wordList if adjacencyList is None: self.adjacencyList = [] else: self.adjacencyList = adjacencyList
PHP 5.3 has a shorthand ?: operator: $foo = $bar ?: $baz; Which assigns $bar if it’s not an empty value (I don’t know how this would be different in PHP from Perl), otherwise $baz, and is the same as this in Perl and older versions of PHP: $foo = $bar ? $bar : $baz; … Read more