'''object''' is perhaps the most overloaded word in computing, with the common
denominator being the idea that an object is a concrete [instance] of some
type of thing in the context of some larger system.



** Description **

At the machine level, a region of memory exposed to a program is called an
'''object''', and assembly programs express operations directly on these
regions.  At the next level up, languages like [C] express operations on values
and their locations in memory, but also express a type for each value such as
"character", "integer", "float", and "array", and constrain operations on the
basis of these types.  In [The C Programming Language Kernighan and
Ritchie%|%The C Programming Language], the first use of the term "object" is in
reference to these primitive types.  At this level, the concept of [class] also
begins to arise, with the various numeric types having a certain degree of
compatibility with each other.

In the context of compiling source code to machine code, [C], an object is an
instance of a compiled unit of source code.  From this meaning comes the term,
'''shared object''', also called a '''[dll%|%dynamic link library]''', which is
a compiled code object that can be linked into a program at runtime.

In [object orientation%|%object-oriented programming], which refers to a set of
[programming language] features which divide the state of a program up into
discrete units, where a particular set of '''[procedure%|%procedures]''' are
responsible for collaborating to manipulate a discrete unit of state, an
'''object''' represents the association of a unit of state with the set of
procedures responsible for managing it.  Each unit of state is composed of
'''data elements''' representing some '''structure''' or '''entity''', and the
procedures associated with it provide an '''[interface]''' for interoperating
with that those data elements.  Typically, each object is either instantiated
from [class%|%classes] or cloned from [Prototype Pattern in Tcl%|%prototypes].
Because of the close relationship between a functional task in a program and
the real-world objects that a program models, [object
orientation%|%object-oriented] programming features are often also used to
organize code according to model function.  Because the organization of code
units needed to implement the model does not necessarily conform the
organization of objects in the model, there an impedence mismatch may occur
when a programmer attempts to use object-oriented programming to align the
organization of program code units with the organization of model objects.

In Tcl, at the implementation level [Tcl_Obj] is a data structure that is used
to implement Tcl values.



** See Also **

   [Object Orientation]:   

   [http://en.wikipedia.org/wiki/Object_%28computer_science%29%|%Wikipedia]:   

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