There is one important, and useful, distinction between the two. Because .ForEach uses a for loop to iterate the collection, this is valid (edit: prior to .net 4.5 – the implementation changed and they both throw): someList.ForEach(x => { if(x.RemoveMe) someList.Remove(x); }); whereas foreach uses an enumerator, so this is not valid: foreach(var item in … Read more
You can write extension methods for enum types: enum Stuff { Thing1, Thing2 } static class StuffMethods { public static String GetString(this Stuff s1) { switch (s1) { case Stuff.Thing1: return “Yeah!”; case Stuff.Thing2: return “Okay!”; default: return “What?!”; } } } class Program { static void Main(string[] args) { Stuff thing = Stuff.Thing1; String … Read more
As of Xcode 7 beta 5 (Swift version 2) you can now print type names and enum cases by default using print(_:), or convert to String using String‘s init(_:) initializer or string interpolation syntax. So for your example: enum City: Int { case Melbourne = 1, Chelyabinsk, Bursa } let city = City.Melbourne print(city) // … Read more
One big difference is that Enumerations come with support for instantiating them from some name String. For example: object Currency extends Enumeration { val GBP = Value(“GBP”) val EUR = Value(“EUR”) //etc. } Then you can do: val ccy = Currency.withName(“EUR”) This is useful when wishing to persist enumerations (for example, to a database) or … Read more
The map method takes an enumerable object and a block, and runs the block for each element, outputting each returned value from the block (the original object is unchanged unless you use map!): [1, 2, 3].map { |n| n * n } #=> [1, 4, 9] Array and Range are enumerable types. map with a … Read more
for (NSString* key in xyz) { id value = xyz[key]; // do stuff } This works for every class that conforms to the NSFastEnumeration protocol (available on 10.5+ and iOS), though NSDictionary is one of the few collections which lets you enumerate keys instead of values. I suggest you read about fast enumeration in the … Read more
The generally-preferred code for 10.5+/iOS. for (id object in array) { // do something with object } This construct is used to enumerate objects in a collection which conforms to the NSFastEnumeration protocol. This approach has a speed advantage because it stores pointers to several objects (obtained via a single method call) in a buffer … Read more
break will exit the loop completely, continue will just skip the current iteration. For example: for (int i = 0; i < 10; i++) { if (i == 0) { break; } DoSomeThingWith(i); } The break will cause the loop to exit on the first iteration – DoSomeThingWith will never be executed. This here: for … Read more
Yes. As of Swift 3.0, if you need the index for each element along with its value, you can use the enumerated() method to iterate over the array. It returns a sequence of pairs composed of the index and the value for each item in the array. For example: for (index, element) in list.enumerated() { … Read more
Depending upon use case, I would normally use something simple like the following: abstract class DaysOfWeek { const Sunday = 0; const Monday = 1; // etc. } $today = DaysOfWeek::Sunday; However, other use cases may require more validation of constants and values. Based on the comments below about reflection, and a few other notes, … Read more