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38 <title>Ada95 Binding for ncurses</title>
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45 <h1>Ada95 Binding for ncurses</h1>
47 <p>by Jürgen Pfeifer.</p>
50 <h2>General Remarks</h2>
53 <li>This document describes Version 01.00 of the binding.</li>
55 <li>The functionality is modeled to be compatible with the
56 ncurses package, a clone of the SVr4 curses model.<br>
57 I did the development on an Intel box running the latest stable
58 release of <a href="http://www.linux.org">Linux</a>, ncurses
59 and the most recent released <a href="http://www.gnat.com">GNU
60 Ada Translator</a> gnat versions. For any older versions of
61 ncurses and gnat it is not guaranteed to work.</li>
63 <li>You must have the m4 macroprocessor to build this package.
64 If you don't have this program, you can get the FSF version
65 <a href="ftp://ftp.gnu.org/pub/gnu/">here</a>.</li>
67 <li>Ada programs are supposed to be readable. One of my
68 favorite methods to make code readable is to use expressive
69 names for the identifiers. You can find a list of a mapping of
70 the cryptic curses names to the Ada names in this <a href=
71 "ada/table.html">table</a>.</li>
73 <li>This is not a typical one-to-one interface mapping. It is
74 close to one-to-one on the functional level. Each (n)curses
75 function has it's counterpart with a more or less similar
76 formal parameter list in the binding. It is not one-to-one with
77 respect to the datatypes. I tried to make records out of the
78 flat chtype and similar structures, so you don't have to do bit
79 operations to mark an attributed character as bold. Just make
80 the boolean member <strong>bold</strong> of the record true.
81 The binding also hides the structures like WINDOW, PANEL, MENU,
82 FORM etc. ! It's a pure functional API.</li>
84 <li>I try to do as much error checking as possible and feasible
85 in the binding. I will raise an Ada exception when something
86 went wrong in the low-level curses. This has the effect that -
87 at least first time in my life - (n)curses programs have now a
88 very rigid error checking, but - thanks to Ada - you don't have
89 to code the orgiastic error checking style of C.</li>
91 <li>Support for wide characters is currently not in the
92 binding, as it is not really in ncurses at this point in
99 <li>I provide no SCREEN datatype and functions to set a new
100 screen. If you need this (mostly for debugging I guess), write
101 a small C routine doing all this and import it into your Ada
104 <li>I provide no functions to switch on/off curses tracing
105 options. Same suggestion as above.</li>
107 <li>Although Ada95 is an OO Language, this binding doesn't
108 provide an OO abstraction of the (n)curses functionality. As
109 mentioned above it's a thin binding for the (n)curses
110 functions. But without any doubt it would be nice to build on
111 top of this an OO abstraction of (n)curses functionality.<br>
112 The only exception is the method how fieldtypes are represented
113 in this Binding. We provide an abstract tagged type Field_Type
114 from which the various fieldtypes are derived.</li>
116 <li>I currently do not support the link_fieldtype functionality
117 of the forms subsystem.</li>
119 <li>The *_IO packages are currently output only.</li>
122 <h2>Hierarchy of packages</h2>
127 "ada/terminal_interface__ads.htm">Terminal_Interface</a>
132 "ada/terminal_interface-curses__ads.htm">Curses</a>
136 "ada/terminal_interface-curses-mouse__ads.htm">Mouse</a></li>
140 "ada/terminal_interface-curses-panels__ads.htm">Panels</a>
144 "ada/terminal_interface-curses-panels-user_data__ads.htm">
151 "ada/terminal_interface-curses-menus__ads.htm">Menus</a>
155 "ada/terminal_interface-curses-menus-menu_user_data__ads.htm">
156 Menu_User_Data</a></li>
159 "ada/terminal_interface-curses-menus-item_user_data__ads.htm">
160 Item_User_Data</a></li>
166 "ada/terminal_interface-curses-forms__ads.htm">Forms</a>
170 "ada/terminal_interface-curses-forms-form_user_data__ads.htm">
171 Form_User_Data</a></li>
174 "ada/terminal_interface-curses-forms-field_user_data__ads.htm">
175 Field_User_Data</a></li>
179 "ada/terminal_interface-curses-forms-field_types__ads.htm">
184 "ada/terminal_interface-curses-forms-field_types-alpha__ads.htm">
188 "ada/terminal_interface-curses-forms-field_types-alphanumeric__ads.htm">
189 AlphaNumeric</a></li>
192 "ada/terminal_interface-curses-forms-field_types-intfield__ads.htm">
196 "ada/terminal_interface-curses-forms-field_types-numeric__ads.htm">
200 "ada/terminal_interface-curses-forms-field_types-regexp__ads.htm">
204 "ada/terminal_interface-curses-forms-field_types-ipv4_address__ads.htm">
205 IPV4_Address</a></li>
209 "ada/terminal_interface-curses-forms-field_types-enumeration__ads.htm">
214 "ada/terminal_interface-curses-forms-field_types-enumeration-ada__ads.htm">
221 "ada/terminal_interface-curses-forms-field_types-user__ads.htm">
226 "ada/terminal_interface-curses-forms-field_types-user-choice__ads.htm">
237 "ada/terminal_interface-curses-text_io__ads.htm">Text_IO</a>
241 "ada/terminal_interface-curses-text_io-integer_io__ads.htm">
245 "ada/terminal_interface-curses-text_io-float_io__ads.htm">
249 "ada/terminal_interface-curses-text_io-fixed_io__ads.htm">
253 "ada/terminal_interface-curses-text_io-decimal_io__ads.htm">
257 "ada/terminal_interface-curses-text_io-modular_io__ads.htm">
261 "ada/terminal_interface-curses-text_io-enumeration_io__ads.htm">
262 Enumeration_IO</a></li>
265 "ada/terminal_interface-curses-text_io-complex_io__ads.htm">
275 <p>If you want to navigate through the html pages of the package
276 specs, click <a href="ada/index.htm">here</a>.</p>
278 <h2>Implementation Details</h2>
280 <h4>Behind the abstraction</h4>
282 <p>All the new types like <strong>Window</strong>,
283 <strong>Panel</strong>, <strong>Menu</strong>,
284 <strong>Form</strong> etc. are just opaque representations of the
285 pointers to the corresponding low level (n)curses structures like
286 <strong>WINDOW *</strong>, <strong>PANEL *</strong>, <strong>MENU
287 *</strong> or <strong>FORM *</strong>. So you can safely pass
288 them to C routines that expect a pointer to one of those
291 <h4>Extended ripoffline() usage</h4>
293 <p>The official documentation of (n)curses says, that the line
294 parameter determines only whether or not exactly
295 <strong>one</strong> line is stolen from the top or bottom of the
296 screen. So essentially only the sign of the parameter is
297 evaluated. ncurses has internally implemented it in a way, that
298 uses the line parameter also to control the amount of lines to
299 steal. This mechanism is used in the
300 <strong>Rip_Off_Lines</strong> routine of the binding.</p>
302 <h4><a name="userpointer" id="userpointer">How user defined field
307 <h4>Enumeration fields handling</h4>
309 <p>The (n)curses documentation says, that the String arrays to be
310 passed to an TYPE_ENUM fieldtype must not be automatic variables.
311 This is not true in this binding, because it is internally
312 arranged to safely copy these values.</p>
314 <h4><a name="compiler" id="compiler">Using other Ada
317 <p>This should basically not be a problem.</p>
319 <h4>Port to other curses implementations</h4>
321 <p>Basically it should not be too hard to make all this run on a
322 regular SVr4 implementation of curses. The problems are probably
326 <li>ncurses has some additional features which are presented in
327 this binding. You have two choices to deal with this:
330 <li>Emulate the feature in this binding</li>
332 <li>Raise an exception for non implemented features</li>
335 <p>Most likely you will follow a mixed approach. Some
336 features are easy to simulate, others will be hard if not
341 <p>I'm quite sure I forgot something.</p>