10

Coding Fragment

Here is an example that illustrates the style of programming with the XView interface in Pascal. This program:

•Creates a vertical scrollbar with a view length of 100 pixels

•Changes the view length to 200 pixels

•Destroys the scrollbar

var bar, pi: Scrollbar;

begin

bar := xv_create ( 0, SCROLLBAR, 0 ); pi := xv_create_l ( 0, SCROLLBAR,

attr_create_list_4s ( SCROLLBAR_VIEW_LENGTH, 100, SCROLLBAR_DIRECTION, SCROLLBAR_VERTICAL));

set_SCROLLBAR_VIEW_LENGTH( bar, 200 ); xv_destroy ( bar );

In this example:

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bar is declared to be of type Scrollbar.

xv_create() and xv_create_l() are invoked as functions. set SCROLLBAR_VIEW_LENGTH () is invoked as a procedure. xv_destroy() is invoked as a procedure.

Conversion of C to Pascal

Here is an example of a problem that you may encounter when converting C to Pascal. It recommends some changes that you can make to work around the problem.

An Example

The Problem—Besides the six standard generic procedures, there are approximately 80 other procedures, plus hundreds of attributes. These are all documented in the XView Programming Manual. The problem is that all of the coding is in C.

The XView Toolkit

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