Glossary
- argument
- An argument is a value which is given to a procedure (or
program) to operate on. For example, in the expression "say( a
)", "a" is the only argument to the "say"
procedure.
- array
- An array is a multi-dimensional list of values. In OADL,
arrays need not contain values of all the same type. For example,
the following is a valid OADL array:
{1,2,"Hi",myClass}*
- ASCII
- American Standard Code for Information Interchange - the
venerable 8-bit standard for the representation of characters. The
ASCII table gives a numeric value for each possible character in
the defined character set; for example, the letter 'a' has the
ASCII value 97.
- class
- A class is a group of data elements and procedures and/or
operators on those elements. Certain of the elements may be made
public so that other classes/objects/contexts may use them.
- constant
- A constant is a value in an OADL program which may not be
modified. Constants are found in many places in an OADL program,
from simple constants like the number "1" to a
complicated class declaration.
- expression
- An expression is a formula that mixes several operands with
operators, returning a result. A typical arithmetic formula is an
expression - for example,
pi*r*r is an
expression.
- floating point
- A floating point number can represent both fractional and
whole numbers. Floating point numbers have a specific magnitude
range and precision depending on their type. Single-precision
numbers have a range of about 1e-38 to 3e38 and a precision of
about 7 decimal digits. Double-precision numbers have a range of
about 2e-308 to 2e308 and a precision of about 16 decimal digits.
Half-precision numbers have a range of about 6e-5 to about 7e4 and
a precision of about 3 decimal digits.
- identifier
- An identifier is a token in a programming language used to
represent a variable, a named constant, named procedure, or other
named item. Typically, identifiers start with an alphabetic
character (as well as some characters such as "_" and
"$") and are followed by any number of alphabetic
characters and numbers
- inheritance
- Inheritance is the ability of classes and objects to be
derived from another parent class. The derived class or instanced
object inherits all of the attributes from its parent.
- integer
- An integer is a whole number whose range depends on the
number of binary digits in the number. There about about 9 digits
of precision for normal integers, about 3 digits of precision for
1-byte integers, about 5 digits of precision for 2-byte integers,
and about 19 digits of precision for 8-byte integers.
- method
- A method is a public procedure interface to a class. A method
is always called on an instance of that class, with the dot call
syntax
obj
.method().
During execution of the method, the self
pseudo-variable can be used to find the Object
instance of the class that the method was called with.
- public
- A public item in a class or object is one which is visible
outside the class/object context. In addition, in OADL, a
Public is a hash key index into an object which
may be declared independently of any class.
- multiple inheritance
- Multiple inheritance is the ability of a class to derive
attributes from more than one parent class. For example, a power
drill might derive attributes from both a cutting tool (number of
teeth, hardness, etc.) as well as from a power tool (spindle size,
motor HP, etc.)
- object
- An object is an instance of a class. Classes are always
non-modifiable; objects may be dynamic, with changes permitted to
various attributes of the object.
- operator
- An operator is one of several mathematical operations,
including
+, -, and so on.
Operators have one (monadic) or two (dyadic)
operands. Operators may be overloaded by OADL classes.
- procedure
- A procedure is a sequence of instructions which tell a
computer what to do. In addition, procedures typically have
arguments - values that are given to the procedure to operate on -
and a return value.
- scalar
- A scalar is a simple single-valued item. For example, the
number 3 is a scalar. In OADL, for the purposes of array-valued
expressions, everything that is not an array is a scalar.
- token
- A token is a sequence of characters which are grouped
together according to a fixed set of rules. An identifier is a
token, as is a string literal, and a floating point number.
- Unicode
- Unicode is the modern standard for encoding text in displayed
output. It handles glyphs from most of the world's languages. OADL
supports the UTF-8 encoding as well as direct 21-bit Unicode glyphs
in a 32-bit field.
- variable
- A variable can be considered a "box" or holding
cell which contains a value. In OADL, most variables have a dynamic
type that may be changed by assigning a new value to the variable.
Back to OADL Format Specifiers
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