Update of /project/cells-gtk/cvsroot/public_html In directory common-lisp.net:/tmp/cvs-serv12344 Modified Files: cgtk-primer.html faq.html Log Message: a few more FAQ answers. Date: Sat Oct 1 21:03:16 2005 Author: pdenno Index: public_html/cgtk-primer.html diff -u public_html/cgtk-primer.html:1.3 public_html/cgtk-primer.html:1.4 --- public_html/cgtk-primer.html:1.3 Mon Mar 7 00:37:35 2005 +++ public_html/cgtk-primer.html Sat Oct 1 21:03:15 2005 @@ -147,7 +147,7 @@ propagation to formula-valued cell dependencies has to happen before any output SETF (and why Cells has a mechanism to defer SETFs of inputs). -<h1>Family: Referencing slots throughout the defmodel hierarchy.</h1> +<h1>Family: Referencing cells throughout the defmodel hierarchy.</h1> The <strong>defmodel</strong> macro defines a part-subpart relationship among components of the interface. The relationship is made by the @@ -160,7 +160,7 @@ <address><a href="mailto:peter.denno@nist.gov">Peter Denno</a></address> <!-- Created: Thu Mar 3 18:45:35 EST 2005 --> <!-- hhmts start --> -Last modified: Sun Mar 6 18:36:16 EST 2005 +Last modified: Sun Mar 6 18:43:09 EST 2005 <!-- hhmts end --> </div> </body> Index: public_html/faq.html diff -u public_html/faq.html:1.7 public_html/faq.html:1.8 --- public_html/faq.html:1.7 Mon Mar 7 00:38:22 2005 +++ public_html/faq.html Sat Oct 1 21:03:15 2005 @@ -36,18 +36,22 @@ <li><a href="#q6">What GTK Widgets are implemented in cells-gtk?</a></li> <li><a href="#q7">Do I have to use cells?</a></li> <li><a href="#q8">What is libcellsgtk.so about?</a></li> + <li><a href="#q8.5">What is the difference between using c-in and c? in a slot's :initform?</a></li> <li><a href="#q9">Why do I need :owner here? It looks like c? would bind self to the mk-whatever enclosing the c?</a></li> <li><a href="#q10">How do I do xyz?</a></li> - <li><a href="#q11">Q: What does this error mean? : "cellular slot FOO of #<BAR 21B555A4> cannot be setf - unless initialized as inputp.</a></li> - <li><a href="#q12">Q: Changing a cell value causes dependencies to fire, but what is considered a change?</li> + <li><a href="#q11">What does this error mean? : "cellular slot FOO of #<BAR 21B555A4> cannot be setf + unless initialized as inputp."</a></li> + <li><a href="#q12">Changing a cell value causes dependencies to fire, but what is considered a change?</li> + <li><a href="#q13">Can I keep a window around for redisplay after using the window border + 'delete' button to delete it?</a></li> + </ul> <p/> <strong id="q1">Q: What is Cells-GTK?</strong><p/> -<strong>A:</strong> Cells-GTK is a GTK binding to lisp written by Vasilis Margioulas. It uses the +<strong>A:</strong> Cells-GTK is a lisp binding of GTK written by Vasilis Margioulas. It uses the Cells system, a sort of constraint propagation system written by kenny tilton. (see "What is Cells?"). As of this writing Cells-GTK runs under Allegro, Lispworks and CMUCL. A separate distribution (not quite up to date with the former) runs @@ -56,7 +60,39 @@ <strong id="q2">Q: What is Cells?</strong><p/> <strong>A:</strong> From the Cells website: "Cells is a mature, stable extension to CLOS that allows you to create classes, the instances of which have slots whose values are determined by - a formula." + a formula." +<p/> Here is an explanation from the viewpoint of a Cells-GTK programmer: + Cells provides Cells-GTK with two essential features: (1) a part-subpart relationship, + as is typically found in GUIs -- it allows the user to express that, e.g., this window contains these + buttons and subwindows etc.; (2) the expression of a program's state machine, as viewed from the + context of the user's interaction through the GUI. This last point is especially noteworthy, and + needs more explanation. If you are at all familiar with developing moderately complex software + that is operated through a GUI, then you have probably learned this: Keeping what is presented through + the GUI in-sync with what the user is allowed to do, and in-sync with the computational state of + the program is often tedious, complicated work. Specifically, there are the issues of what menu items + ought to be made sensitive when, what items should be presented in list, what text should appear in + entries, etc. Cells-GTK helps with these tasks by providing an abstraction over the details; each + of the tasks just listed can be controlled by (a) rules that specify the value of attributes of graphic + features in the part-subpart declaration (that declaration is called 'defpart' in cells-gtk); + and, (b) rules that specify the value of CLOS slots. [Footnote, In the details of the implementation, + (a) is just a usage of (b). But it helps to think of the ability to set a GUI feature with a + rule as something different than setting the value of slot with a rule.]. An example of (a) + is setting the :sensitive feature of a GTK menu item. For this, I might use the rule (c? (user-file *my-gui*)). + Here user-file is the accessor of some object *my-gui*. :sensitive is a boolean, so whenever there + is a non-nil value in the slot user-file, the menu item is sensitive. That doesn't look a whole lot + different than giving :sensitive whatever value (user-file *my-gui*) evaluates to. + The difference is that in Cells-GTK, the Cells codes watches over 'instrumented' slots such as user-file + and automatically updates those attributes of a Cell-GTK object (such as a menu item's :sensitive feature) + that are governed by a Cells rule. Thus, I don't have to explicitly update the value of + :sensitive -- it happens automatically. + <p/> + So what is this talk about 'expression of a program's state machine?' Well, the idea is that + in a GUI operated by Cells-GTK, transition into a state is governed by cells-rules on + GUI features and cells-instrumented slots. E.g. when the user loads a file, (c? (user-file *my-gui*)) + becomes true and the program enters the state where some menu item that wasn't sensitive now is + -- the cells rules are rules on the arcs out of states. Is that stretching it too much? + I don't know, it makes sense to me. + <p/> See also: <ul> <li><a href="http://common-lisp.net/project/cells/"> @@ -68,6 +104,7 @@ </ul> <p/> + <strong id="q3">Q: Why is the Clisp distribution separate?</strong><p/> <strong>A:</strong> Because as of this writing, UFFI, which Cells-GTK uses, doesn't support CLISP. <p/> @@ -82,7 +119,22 @@ <p/> <strong id="q6">Q: What GTK Widgets are implemented in cells-gtk?</strong><p/> <strong>A:</strong> [hmm, Better to ask what isn't. Most of the useful widgets are implemented, but - among those, many non-essential methods are not.] + among those, many non-essential methods are not.] A quick look at the +<a href="http://developer.gnome.org/doc/API/2.0/gtk/ch02.html">widget gallery</a>. These +are not implemented: +<ul> + <li>GtkColorButton</li> + <li>GtkFileChooserButton </li> + <li>GtkFontButton </li> + <li>GtkIconView</li> + <li>GtkStatusBar</li> + <li>GtkFontSelectionDialog</li> + <li>GtkColorSelectionDialog</li> +</ul> +<p/>There are quite a few other widgets not listed in the Gallery that aren't implmented. +But BTW, it isn't difficult to implement most of these. If you need one, implemented +it and drop us a note! + <p/> <strong id="q7">Q: Do I have to use cells?</strong><p/> <strong>A:</strong> Probably not. But the demo uses them, so it might still be (despite the lack of @@ -143,6 +195,14 @@ the libgtk.so you are using. <p/> + +<p/> +<strong id="q8.5">Q: What is the difference between using c-in and c? in a slot's :initform ?</strong><p/> +<strong>A:</strong> The usual semantics of :initform do not apply when :initform is given a c? rule. +Instead of just setting the value at initialization, when c? is used, the value of the slot is +checked and updated using the rule throughout program execution. +<p/> + <strong id="q9">Q: Why do I need :owner here? It looks like c? would bind self to the mk-whatever enclosing the c?</strong><p/> <tt> @@ -179,7 +239,7 @@ </pre> </tt> <p/> -<strong>A:</strong> If you macroexpand callback, you will see that ith binds self again, this time to the +<strong>A:</strong> If you macroexpand callback, you will see that it binds self again, this time to the menu-item. <br/><tt>(owner self)</tt> gets you into the :kids hierarchy. <p/> <strong id="q10">Q: How do I do xyz?</strong><p/> @@ -200,6 +260,25 @@ dependencies to fire again (in order to save substantial useless recalculations). So how is "equivalence" defined? EQL is used unless overridden by providing a function of two arguments to :unchanged-if in the slot definition of the defmodel. + + +<p/> +<strong id="q13">Q: Can I keep a window around for redisplay after using the window border + 'delete' button to delete it?</strong><p/> + <strong>A:</strong>Yes. Do something like this: + +<tt> +<pre> +(defmodel pseudo-dialog (window) + () + (:default-initargs + :on-delete-event (callback (w e d) (gtk-widget-hide-on-delete w)))) +</pre> +</tt> +<p/> +... and, of course, store the widget somewhere so you can later display it with + (gtk-widget-show-all (widget-id my-pseudo-dialog)). + <hr/> <address><a href="mailto:peter.denno@nist.gov">Peter Denno</a></address>