The directory location of the Paradox network control file PDOXUSRS.NET. The active NET DIR parameter is stored in the Paradox section of the BDE configuration file and has precedence over any other NET DIR parameters that may be stored in older 16-bit configuration files, or in the System Init section of the current configuration file, or in the Registry. These other NET DIR entries will have no effect. To access a Paradox table on a network drive, the active NET DIR parameter in the Paradox section of the BDE configuration file must point to a network drive and folder in common to all users.

A constant is just like a variable (it holds a value) but, unlike a variable, you cannot change the value of a constant.

In computer programming, an event handler is part of event driven programming where the events are created by the framework based on interpreting inputs. Each event allows you to add code to an application-level event generated by the underlying framework, typically GUI triggers such as a key press, mouse movement, action selection, and an expired timer. In addition, events can represent data changes, new data, etc. Specifically, an event handler is an asynchronous callback subroutine that handles inputs received in a program.

A custom event is a programmer created event. For example, you can contrast an event handler with a member event, an OOP concept where you add an event to a class.

Instead of calling a routine, you move the code from the routine itself and expand it in place of the call. In addition to manual inlining, some languages support automatic inlining where the compiler or some other pre-compiler decides when to inline a code routine. Also, some languages allow for developer defined inlining where the developer can suggest and/or force the inlining of a code routine. Inlining can optimize your code for speed by saving a call and return, and parameter management.

Types of overloading include method overloading and operator overloading.

Method Overloading is where different functions with the same name are invoked based on the data types of the parameters passed or the number of parameters. Method overloading is a type of polymorphism and is also known as Parametric Polymorphism.

Operater Overloading allows an operator to behave differently based on the types of values used. For example, in some languages the + operator is used both to add numbers and to concatenate strings. Custom operator overloading is sometimes referred to as ad-hoc polymorphism.

A pointer is a variable type that allows you to refer indirectly to another object. Instead of holding data, a pointer holds the address to data -- the address of another variable or object. You can change the address value a pointer points to thus changing the variable or object the pointer is pointing to.

A reference is a type of pointer that cannot change and it must always point to a valid storage (no nulls).

A value directly written into the source code of a computer program (as opposed to an identifier like a variable or constant). Literals cannot be changed. Common types of literals include string literals, floating point literals, integer literals, and hexidemal literals. Literal strings are usually either quoted (") or use an apostrophe (') which is often referred to as a single quote. Sometimes quotes are inaccurately referred to as double quotes.

An operation with only one operand (a single input). Common unary operators include + plus, - minus, and bitwise not. Some operators can function as both unary and binary operators. For example, + and - operators can serve as either.

An abstract class member is a member that is specified in a class but not implemented. Classes that inherit from the class will have to implement the abstract member. Abstract members are a technique for ensuring a common interface with descendant classes. An abstract class is a class you cannot instantiate. A pure abstract class is a class with only abstract members.

Aggregations indicate a whole-part relationship, and are known as "has-a" or "is part of" relationships. An Aggregation relationship is indicated by a line with a hollow diamond.

Constructors are called when you instantiate an object from a class. This is where you can initialize variables and put code you wish executed each time the class is created. When you initially set the member fields and properties of an object, you are initializing the state of the object. The state of an object is the values of all it's member fields and properties at a given time.

A special class method called when an object instance of a class is destroyed. With some languages they are called when the object instance goes out of scope, with some languages you specifically have to call the destructor in code to destroy the object, and others use a garbage collector to dispose of object instances at specific times.

Desctructors are commonly used to free the object instance but with languages that have a garbage collector object instances are disposed of when appropriate. Either way, destructors or their equivalent are commonly used to free up resources allocated in the class constructor.

A. In Dephi, class helpers allow you to extend a class without using inheritance. With a class helper, you do not have to create and use a new class descending from a class but instead you enhance the class directly and continue using it as you always have (even just with the DCU).

B. In general terms, developers sometimes use the term to refer to any class that helps out another class.

A.k.a. Class Contract and Design by Contracts.

A contract with a method that must be true upon calling (pre) or exiting (post). A pre-condition contract must be true when the method is called. A post-condition contract must be true when exiting. If either are not true, an error is raised. For example, you can use code contracts to check for the validity of input parameters, and results

An invariant is also a code contract which validates the state of the object required by the method.

The concept of a class makes it possible to define subclasses that share some or all of the main class characteristics. This is called inheritance. Inheritance also allows you to reuse code more efficiently. In a class tree, inheritance is used to design classes vertically. (You can use Interfaces to design classes horizontally within a class tree.) With inheritance, you are defining an "is-a" relationship (i.e. a chow is-a dog). Analysts using UML call this generalization where you generalize specific classes into general parent classes.

An element of coding where you define a common set of properties and methods for use with the design of two or more classes.

Both interfaces and abstract classes are types of abstraction. With interfaces, like abstract classes, you cannot provide any implementation. However, unlike abstract classes, interfaces are not based on inheritance. You can apply an Interface to any class in your class tree. In a real sense, interfaces are a technique for designing horizontally in a class hierarchy (as opposed to inheritance where you design vertically). Using interfaces in your class design allows your system to evolve without breaking existing code.

A custom event added by a programmer to a class. Custom created events need to be processed, usually by an event dispatcher within a framework.

Also known as a Class Field.

A class variable defined with a specific class visibility, usually private visibility. A member property is different than a member field. A member property uses a member field to store values through accessor methods (getters and setters). For example, it is common to use a private member field to store the current value of a property. The current values of all the class member fields is the current state of the object.

Also known as a Class Method.

A code routine that belongs to the class or an object instance (an instance of the class). Methods that belong to the class are called class methods or static methods. Methods that belong to an object instance are called instance methods, or simply methods.

When a method returns a value, it is a function method. When no value is returned (or void), it is a procedure method.

Methods frequently use method parameters to transfer data. When one object instance calls another object instance using a method with parameters, you call that messaging.

Where you define or implement a virtual method in a parent class and then replace it in a descendant class.

When you decide to declare a method as virtual, you are giving permission to derived classes to extend and override the method with their own implementation. You can have the extended method call the parent method's code too.

In most OO languages you can also choose to hide a parent method. When you introduce a new implementation of the same named method with the same signature without overriding, you are hiding the parent method.

A partial class, or partial type, is a class that can be split into two or more source code files and/or two or more locations within the same source file. Each partial class is known as a class part or just a part. Logically, partial classes do not make any difference to the compiler. The compiler puts the class together at compile time and treats the final class or type as a single entity exactly the same as if all the source code was in a single location.

A coding technique where the same named function, operator, or object behaves differently depending on outside input or influences. Usually implemented as parameter overloading where the same named function is overloaded with other versions that are called either with a different type or number of parameters. Polymorphism is a general coding technique and other specific implementations are common such as inheritance, operator overloading, and interfaces.

A static member is a member you can have access to without instantiating the class into an object. For example, you can read and write static properties and call static methods without ever creating the class. Static members are also called class members (class methods, class properties, etc.) since they belong to the class and not to a specific object. A static class is a class that contains only static members. In the UML, these classes are described as utility classes.

Microsoft's implementation of NetBIOS Name Service (NBNS), a name server and service for NetBIOS computer names. Just as DNS serves up domain names, WINS serves up NetBios names and is particularly useful within a Microsoft-based network when or without the NetBIOS protocol installed. Use of WINS will decrease broadcast traffic.

A checkpoint is NOT a task, but rather a milestone. A point in the project that marks significant progress. Although PSDP contains many standard checkpoints, the executive sponsor and project manager must agree on the checkpoints they wish to track. Once established, tasks can be associated with a checkpoint and you can easily view what tasks are completed per checkpoint and what checkpoints do NOT have tasks established yet.

Delphi Prism Self Keyword

Within the implementation of a method, the identifier Self references the object in which the method is called. The Self variable is an implicit parameter for each object method. A method can use this variable to refer to its owning class.

To refer to the current instance of a class or structure, use the Self keyword. It provides a way to refer to the specific instance in which the code is currently executing. It is particularly useful for passing information about the currently executing instance.

You cannot use it with static method functions because static methods do not belong to an object instance. If you try, you'll get an error.