enumeration

While there are many questions on S/O regarding difficulties with Scala Enumeration, I haven't found a question that addresses my problem. Specifically, I am trying to translate the Planet example from the Oracle Java enum docs into the Scala Enumeration idiom so as to better understand the workings and pro's & con's of the Scala form. My ported code so far appears below and, suffice to say, it does not compile as might be expected from the principle of least surprise. Apart from type casting with .asInstanceOf, is there a better or accepted solution? Thanks, Justin object Planet extends

I want to automatically convert/coerce strings into Scala Enumeration Values, but without knowing beforehand what Enumeration subclass (subobject?) the declaration is from. So, given: object MyEnumeration extends Enumeration { type MyEnumeration = Value val FirstValue, SecondValue = Value } and class MyThing { import MyEnumeration._ var whichOne: MyEnumeration = FirstValue } how would I implement the following? val myThing = new MyThing() setByReflection(myThing, "whichOne", "SecondValue") What I'm finding is that when I get the class of MyThing.whichOne (via java.lang.Field), the return is

Is it possible to use fast enumeration with an NSArray that contains an NSDictionary? I'm running through some Objective C tutorials, and the following code kicks the console into GDB mode NSMutableArray *myObjects = [NSMutableArray array]; NSArray *theObjects = [NSArray arrayWithObjects:@"easy as 1",@"easy as two", @"Easy as Three"]; NSArray *theKeys = [NSArray arrayWithObjects:@"A",@"B",@"C"]; NSDictionary *theDict = [NSDictionary dictionaryWithObjects:theObjects forKeys:theKeys]; [myObjects addObject:theDict]; for(id item in myObjects) { NSLog(@"Found an Item: %@",item); } If I replace the

At Vulkan specs 1.0.9 (pg. 180), we have the following: typedef struct VkMemoryHeap { VkDeviceSize size; VkMemoryHeapFlags flags; } VkMemoryHeap; and this description: • size is the total memory size in bytes in the heap. • flags is a bitmask of attribute flags for the heap. The bits specified in flags are: typedef enum VkMemoryHeapFlagBits { VK_MEMORY_HEAP_DEVICE_LOCAL_BIT = 0x00000001, } VkMemoryHeapFlagBits; But when I query VkPhysicalDeviceMemoryProperties I've got flags with zero values. My code matches the output from Vulkan SDK vkjson_info.exe tool, which output a JSON file with

Basic Question: I have a k dimensional box. I have a vector of upper bounds and lower bounds. What is the most efficient way to enumerate the coordinates of the vertices? Background: As an example, say I have a 3 dimensional box. What is the most efficient algorithm / code to obtain: vertex[0] = ( 0, 0, 0 ) -> ( L_0, L_1, L_2 ) vertex[1] = ( 0, 0, 1 ) -> ( L_0, L_1, U_2 ) vertex[2] = ( 0, 1, 0 ) -> ( L_0, U_1, L_2 ) vertex[3] = ( 0, 1, 1 ) -> ( L_0, U_1, U_2 ) vertex[4] = ( 1, 0, 0 ) -> ( U_0, L_1, L_2 ) vertex[5] = ( 1, 0, 1 ) -> ( U_0, L_1, U_2 ) vertex[6] = ( 1, 1, 0 ) -> ( U_0, U_1, L_2 )

I read an answer on SO where someone said that scala enumerations are useless , and you should just use java enumerations instead if you really need too. Although I have used java enumerations before, I can't say I fully understand them as I don't code in java during my day job. Can someone explain the differences between scala and java enumerations, and where exactly the shortcomings in scala enums are? The main advantage of Scala's Enumeration is the regularity of the syntax. If you want to add behavior to elements of your enum, just extend its Val class. Odersky likes them for their

Does Scheme/Racket have an enumeration notation equivalent to the [a..b] notation in Haskell? In Haskell, [1..5] evaluates to a list [1,2,3,4,5]. (for/list ([i (in-range 1 6)]) i) (sequence->list (in-range 1 6)) (require srfi/1) (iota 5 1) (for/list ([i 5]) (+ 1 i)) (build-list 5 add1) Also, (in-range 1 6) (which is a sequence ) by itself is useful in many contexts. 来源： https://stackoverflow.com/questions/7144248/does-scheme-racket-have-an-enumeration-operation

I'm trying to log the contents of the HttpServletRequest attributes collection. I need to do this when the servlet first starts, and again right before the servlet is finished. I'm doing this in an attempt to understand a crufty and ill-maintained servlet. Because I need to have as little impact as possible, servlet filters are not an option. So here's the problem. When the servlet starts, I'll iterate through the enumeration returned by HttpServletRequest.getAttributeNames(). However, when I want to iterate through it again, getAttributeNames().hasMoreElements() returns "false"! I can't find

I have enum say ErrorCodes that public enum ErrorCodes { INVALID_LOGIN(100), INVALID_PASSWORD(101), SESSION_EXPIRED(102) ...; private int errorCode; private ErrorCodes(int error){ this.errorCode = error; } //setter and getter and other codes } now I check my exception error codes with this error codes. I don't want to write if this do this, if this do this. How I can solve this problem (writing 10+ if blocks) Is there any design patter to that situation ? Thanks As pointed out by Spoike, using polymorphism to pick the right error handling method is an option. This approach basically defers the