Typically, I’ve seen people use the class literal like this: Class<Foo> cls = Foo.class; But what if the type is generic, e.g. List? This works fine, but has a warning since List should be parameterized: Class<List> cls = List.class So why not add a <?>? Well, this causes a type mismatch error: Class<List<?>> cls = … Read more
I’m playing around with Java’s reflection API and trying to handle some fields. Now I’m stuck with identifying the type of my fields. Strings are easy, just do myField.getType().equals(String.class). The same applies for other non-derived classes. But how do I check derived classes? E.g. LinkedList as subclass of List. I can’t find any isSubclassOf(…) or … Read more
Consider this class: class foo(object): pass The default string representation looks something like this: >>> str(foo) “<class ‘__main__.foo’>” How can I make this display a custom string? 5 Answers 5
I need to have a class constructor in PHP call its parent’s parent’s (grandparent?) constructor without calling the parent constructor. // main class that everything inherits class Grandpa { public function __construct() { } } class Papa extends Grandpa { public function __construct() { // call Grandpa’s constructor parent::__construct(); } } class Kiddo extends Papa … Read more
In Swift you can check the class type of an object using ‘is’. How can I incorporate this into a ‘switch’ block? I think it’s not possible, so I’m wondering what is the best way around this. 4 Answers 4
In the following blog: http://weblogs.asp.net/scottgu/archive/2010/07/16/code-first-development-with-entity-framework-4.aspx The blog contains the following code sample: public class Dinner { public int DinnerID { get; set; } public string Title { get; set; } public DateTime EventDate { get; set; } public string Address { get; set; } public string HostedBy { get; set; } public virtual ICollection<RSVP> RSVPs … Read more
I have realized that it is possible to create widgets using plain functions instead of subclassing StatelessWidget. An example would be this: Widget function({ String title, VoidCallback callback }) { return GestureDetector( onTap: callback, child: // some widget ); } This is interesting because it requires far less code than a full-blown class. Example: class … Read more
Can someone define what exactly ‘POCO’ means? I am encountering the term more and more often, and I’m wondering if it is only about plain classes or it means something more? 11 Answers 11
In Java, you can define multiple top level classes in a single file, providing that at most one of these is public (see JLS §7.6). See below for example. Is there a tidy name for this technique (analogous to inner, nested, anonymous)? The JLS says the system may enforce the restriction that these secondary classes … Read more
Is there any difference at all between these classes besides the name? class WithClass (): def __init__(self): self.value = “Bob” def my_func(self): print(self.value) class WithoutClass (): value = “Bob” def my_func(self): print(self.value) Does it make any difference if I use or don’t use the __init__ method for declaring the variable value? My main worry is … Read more
