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Introduction to Tix
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What is in
Variables
Each widget instance is associated with a set of variables. In the
example of an instance of the TixArrowButton class, we may use a
variable to store the direction to which the arrow is pointing
to. We may also use a variable to count how many times the user has
pressed the button.
Each variable can be public or private. Public variables may be
accessed by the application programmer (usually via
configure
or cget
methods
) and their names usually start with a dash
(
-
). They usually are used to represent some user-configurable
options of the widget instance. Private variables, on the other
hand, cannot be accessed by the application programmer. They are
usually used to store information about the widget instance that are
of interests only to the widget writer.
All the variables of an instance are stored in a global array that
has the same name as the instance. For example, the variables of the
instance
.up
are stored in the global array
.up:
. The
public variable
-direction
, which records the direction to
which the arrow is pointing to, is stored in
.up(-direction)
.
The private variable
count
, which counts how many times the
user has pressed the button, is stored in
.up(count)
. In
comparison, the same variables of the
.down
instance are
stored in
.down(-direction)
and
.down(count)
.
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http://tix.sourceforge.net
