7.27.2015

​The observer pattern is a software design pattern in which an object, called the subject, maintains a list of its dependents, called observers, and notifies them automatically of any state changes, usually by calling one of their methods. It is mainly used to implement distributed event handling systems. 

(source wikipedia)

StatusQuo is a new programming system for developing database applications using the Java language. It uses program analysis techniques to do two things:

Identify parts of the program that operate on database result sets and convert them into SQL. For example, our system converts a nested loop on a Java ResultSet into equivalent SQL to allow the database pick the best join algorithm.

Move blocks of code into the database as stored procedures, to reduce the number of network round trips and move code closer to data.

StatusQuo maintains the status quo, because it the programmer doesn't need to modify his or her code at all. Programmers write applications in Java as they always have, and StatusQuo optimizes the application during compile and execution time. There is no need to install any custom database or app server. 

(source: http://db.csail.mit.edu/statusquo/)

​In computer science, future, promise, and delay refer to constructs used for synchronization in some concurrent programming languages. They describe an object that acts as a proxy for a result that is initially unknown, usually because the computation of its value is yet incomplete. 

(source: wikipedia)

​A closure is a function, whose return value depends on the value of one or more variables declared outside this function. Consider the following piece of code with anonymous function 

(source: http://www.tutorialspoint.com/scala/scala_closures.htm

Scala: Anonymous Function Syntax 

Stateful means the computer or program keeps track of the state of interaction, usually by setting values in a storage field designated for that purpose. Stateless means there is no record of previous interactions and each interaction request has to be handled based entirely on information that comes with it. 

(source: http://whatis.techtarget.com/definition/stateless)

In compiler optimization, escape analysis is a method for determining the dynamic scope of pointers - where in the program a pointer can be accessed. It is related to pointer analysis and shape analysis.

When a variable (or an object) is allocated in a subroutine, a pointer to the variable can escape to other threads of execution, or to calling subroutines. 

If a subroutine allocates an object and returns a pointer to it, the object can be accessed from undetermined places in the program — the pointer has "escaped". Pointers can also escape if they are stored in global variables or other data structures that, in turn, escape the current procedure. 

(source: wikipedia)​

​subroutine is a sequence of program instructions that perform a specific task, packaged as a unit. This unit can then be used in programs wherever that particular task should be performed. 

(source: wikipedia)

function composition (not to be confused with object composition) is an act or mechanism to combine simple functions to build more complicated ones. Like the usual composition of functions in mathematics, the result of each function is passed as the argument of the next, and the result of the last one is the result of the whole.

Programmers frequently apply functions to results of other functions, and almost all programming languages allow it. In some cases, the composition of functions is interesting as a function in its own right, to be used later. 

The ability to easily compose functions encourages factoring (breaking apart) functions for maintainability and code reuse. More generally, big systems might be built by composing whole programs.​

(source: wikipedia)​