glossary

What is the purpose of annotations in Java? I have this fuzzy idea of them as somewhere in between a comment and actual code. Do they affect the program at run time? What are their typical usages? Are they unique to Java? Is there a C++ equivalent? Anders Sandvig Annotations are primarily used by code that is inspecting other code. They are often used for modifying (i.e. decorating or wrapping) existing classes at run-time to change their behavior. Frameworks such as JUnit and Hibernate use annotations to minimize the amount of code you need to write yourself to use the frameworks. Oracle has

Since debate without meaningful terms is meaningless , I figured I would point at the elephant in the room and ask: What exactly makes a language "object-oriented"? I'm not looking for a textbook answer here, but one based on your experiences with OO languages that work well in your domain, whatever it may be. A related question that might help to answer first is: What is the archetype of object-oriented languages and why? Definitions for Object-Orientation are of course a huge can of worms , but here are my 2 cents: To me, Object-Orientation is all about objects that collaborate by sending

Recently Jeff has posted regarding his trouble with database deadlocks related to reading. Multiversion Concurrency Control (MVCC) claims to solve this problem. What is it, and what databases support it? updated: these support it (which others?) oracle postgresql Oracle has had an excellent multi version control system in place since very long(at least since oracle 8.0) Following should help. User A starts a transaction and is updating 1000 rows with some value At Time T1 User B reads the same 1000 rows at time T2. User A updates row 543 with value Y (original value X) User B reaches row 543

Related to my CouchDB question. Can anyone explain MapReduce in terms a numbnuts could understand? Going all the way down to the basics for Map and Reduce. Map is a function which "transforms" items in some kind of list to another kind of item and put them back in the same kind of list. suppose I have a list of numbers: [1,2,3] and I want to double every number, in this case, the function to "double every number" is function x = x * 2. And without mappings, I could write a simple loop, say A = [1, 2, 3] foreach (item in A) A[item] = A[item] * 2 and I'd have A = [2, 4, 6] but instead of writing

I keep hearing this term tossed around in several different contexts. What is it? 1800 INFORMATION Declarative programming is when you write your code in such a way that it describes what you want to do, and not how you want to do it. It is left up to the compiler to figure out the how. Examples of declarative programming languages are SQL and Prolog. The other answers already do a fantastic job explaining what declarative programming is, so I'm just going to provide some examples of why that might be useful. Context Independence Declarative Programs are context-independent . Because they only

What does the word "literal" mean when used in context such as literal strings and literal values? What is the difference between a literal value and a value? A literal is "any notation for representing a value within source code" ( wikipedia ) (Contrast this with identifiers , which refer to a value in memory.) Examples: "hey" (a string) false (a boolean) 3.14 (a real number) [1,2,3] (a list of numbers) (x) => x*x (a function) /^1?$|^(11+?)\1+$/ (a regexp) Some things that are not literals: std::cout (an identifier) foo = 0; (a statement) 1+2 (an expression) A literal is a value that has been