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How to learn wxWidgets programming
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<P>

The following is a response by Edward Ream to a common question,
"What's the best way to learn wxWidgets [and C++]?".<P>

Date: Sun, 04 Jun 2000 14:37:06 -0500<BR>
From: "Edward K. Ream" <edream@tds.net> <BR>
To: wx-users@wxwidgets.org<BR>
Subject: Re: [wx-users] How to learn using wx-windows <BR>
Reply-To: wx-users@wxwidgets.org<P>

&gt; Reading the Linux Journal article on wxpython, and having used wxclips<BR>
&gt; I got interested in wxwidgets as a development interface. However, the<BR>
&gt; programming experience I got is old, and from a former generation (For-<BR>
&gt; tran). I'd like to refresh my experience and start in C++.  Will<BR>
&gt; wx-windows be a very high step to take?<P>

I'm new to wxWidgets myself, but I'd like to answer this question
anyway. In the past two years I've learned two similar frameworks
(Apple's Yellow Box, aka NextStep/OpenStep and Borland's C++
Builder/Delphi) and last year I became a C++ enthusiast after 20 years
of using C.<P>

<B>About C++.</B><P>

The major Aha for me was that the complexity of C++ doesn't matter in
practice.  What _does_ matter is that C++ allows you to do simple things
simply, more simply than C.  With a system like wxWidgets you will be
creating objects and then using those objects to call methods.  So don't
be afraid of C++: you'll only be using the easy tip of the
iceberg.<P>

Besides the C++ Programming Language, by Bjarne Stroustrup, the
"official" guide to C++, I highly recommend Inside the C++ Object Model,
by Stanley B. Lippman.  (Lippman was one of the C++ honchos at Bell
Labs.)  This book will tell you what _not_ to do, as well as why
everything in C++ is as it is.  If you are confused by anything in C++,
Lippman's book is the cure.<P>

<B>About applications frameworks.</B><P>

Application frameworks such as wxWidgets are organized around a set of
cooperating classes.  Take a look at the main application class, wxApp,
some frame and panel classes, graphics classes, menu classes, control
classes, etc.  In general, to do anything in a framework involves
creating an object of the specified type, then doing something with that
object.<P>

For example, suppose you want to create a menu bar.  A menu bar is
composed of a single menu bar object of type(class) wxMenuBar that
contains menu objects of type wxMenu.  Each menu object contains menu
item objects of type wxMenuItem.  So you create the menu bar object,
then create all the menu objects (creating the menu item objects along
the way) and finally "attach" the menu objects to the menu bar object
using a call to the wxMenuBar::Append method.<P>

As an overview I would look at the "Alphabetical class reference"
section of the reference manual.  I find the HTML version to be the
easiest to use:  you can browse very quickly through it.  Here's how to
read this (very large) reference:<P>

<ol>
<li>Get an overview of the kinds of classes involved.  The class names
will tell you a lot about what each class does.  Open some of the
classes, in particular, wxApp (the main application object), wxFrame,
wxControl (the base class for all controls) and one or two controls,
like wxButton.

<li>When scanning a class for the first several times, read the
introductory remarks and quickly scan the list of methods of the class
to get a general idea about what kinds of operations can be done to
objects of the class.  You are not looking for detail at this stage,
just for the big picture.  In particular, what classes exist and how do
they work together.

<li>Pay particular attention to the classes from which a class is
derived.  For example, a button (an object of type wxButton) is derived
from the wxControl, wxWindow, wxEvtHandler and wxObject classes.  What
does this mean?  It means that a button _is_ a control, and a button
_is_ a window, and a button _is_ an event handler and a button _is_ an
object.  So you must understand the parent classes of an object to
understand the object itself.

For example, if b is a button you can invoke b.m for any of method m of
the wxControl, wxWindow, wxEvtHandler or wxObject classes.  You are not
limited to just the methods of wxButton!  This is one of the keys of
object oriented programming.
</ol>

Some other tips:<P>

Read some sample code.  You will find that almost none of the C++
language is actually being used; it's just endlessly creating objects
and then calling methods using those objects.<P>

Learn as much as you can about the String class; after using a good
String class you'll never want to use C's string functions again. 
wxWidgets contains other nifty utility classes as well.<P>

The application class, wxApp, contains the main event loop.  Learn about
event handling and event tables (reading sample code will help). Almost
everything in this kind of application framework happens as the result
of an event and your app is essentially doing nothing but responding to
events.  Having the event loop written for you is a major, major
benefit.<P>

I hope this helps. Perhaps we can work together in learning about
wxWidgets.  Please feel free to ask me any questions you might have.  If
I've made any blunders in this posting I hope the wxWidgets experts will
correct me gently.<P>

Edward<BR>
--------------------------------------------------------------------<BR>
Edward K. Ream   email:  edream@tds.net<BR>
Leo: Literate Editor with Outlines<BR>
Leo: http:&#47;&#47;personalpages.tds.net/~edream/front.html<BR>
--------------------------------------------------------------------<P>

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f6bcfd97 BP	1	<HTML>
	2
	3	<HEAD>
fc2171bd	4	<TITLE>How to learn wxWidgets programming</TITLE>
f6bcfd97 BP	5	</HEAD>
	6
	7	<BODY BGCOLOR=#FFFFFF TEXT=#000000 LINK=#FF0000 VLINK=#000000>
	8
	9	<font face="Arial, Lucida Sans, Helvetica">
	10
	11	<a name="top"></a>
	12
	13	<table align=center width=100% border=4 cellpadding=5 cellspacing=0>
	14	<tr>
	15	<td bgcolor="#660000" align=left colspan=2>
	16	<font size=+1 face="Arial, Lucida Sans, Helvetica" color="#FFFFFF">
fc2171bd	17	How to learn wxWidgets programming
f6bcfd97 BP	18	</font>
	19	</td>
	20	</tr>
	21	</table>
	22
	23	<P>
	24
	25	The following is a response by Edward Ream to a common question,
fc2171bd	26	"What's the best way to learn wxWidgets [and C++]?".<P>
f6bcfd97 BP	27
	28	Date: Sun, 04 Jun 2000 14:37:06 -0500<BR>
	29	From: "Edward K. Ream" <edream@tds.net> <BR>
77ffb593	30	To: wx-users@wxwidgets.org<BR>
f6bcfd97	31	Subject: Re: [wx-users] How to learn using wx-windows <BR>
77ffb593	32	Reply-To: wx-users@wxwidgets.org<P>
f6bcfd97	33
2edb0bde	34	> Reading the Linux Journal article on wxpython, and having used wxclips<BR>
77ffb593	35	> I got interested in wxwidgets as a development interface. However, the<BR>
2edb0bde VZ	36	> programming experience I got is old, and from a former generation (For-<BR>
	37	> tran). I'd like to refresh my experience and start in C++. Will<BR>
	38	> wx-windows be a very high step to take?<P>
f6bcfd97	39
fc2171bd	40	I'm new to wxWidgets myself, but I'd like to answer this question
f6bcfd97 BP	41	anyway. In the past two years I've learned two similar frameworks
	42	(Apple's Yellow Box, aka NextStep/OpenStep and Borland's C++
	43	Builder/Delphi) and last year I became a C++ enthusiast after 20 years
	44	of using C.<P>
	45
	46	<B>About C++.</B><P>
	47
	48	The major Aha for me was that the complexity of C++ doesn't matter in
	49	practice. What _does_ matter is that C++ allows you to do simple things
fc2171bd	50	simply, more simply than C. With a system like wxWidgets you will be
f6bcfd97 BP	51	creating objects and then using those objects to call methods. So don't
	52	be afraid of C++: you'll only be using the easy tip of the
	53	iceberg.<P>
	54
	55	Besides the C++ Programming Language, by Bjarne Stroustrup, the
	56	"official" guide to C++, I highly recommend Inside the C++ Object Model,
2edb0bde	57	by Stanley B. Lippman. (Lippman was one of the C++ honchos at Bell
f6bcfd97 BP	58	Labs.) This book will tell you what _not_ to do, as well as why
	59	everything in C++ is as it is. If you are confused by anything in C++,
	60	Lippman's book is the cure.<P>
	61
	62	<B>About applications frameworks.</B><P>
	63
fc2171bd	64	Application frameworks such as wxWidgets are organized around a set of
f6bcfd97 BP	65	cooperating classes. Take a look at the main application class, wxApp,
	66	some frame and panel classes, graphics classes, menu classes, control
	67	classes, etc. In general, to do anything in a framework involves
	68	creating an object of the specified type, then doing something with that
	69	object.<P>
	70
	71	For example, suppose you want to create a menu bar. A menu bar is
	72	composed of a single menu bar object of type(class) wxMenuBar that
	73	contains menu objects of type wxMenu. Each menu object contains menu
	74	item objects of type wxMenuItem. So you create the menu bar object,
	75	then create all the menu objects (creating the menu item objects along
	76	the way) and finally "attach" the menu objects to the menu bar object
	77	using a call to the wxMenuBar::Append method.<P>
	78
	79	As an overview I would look at the "Alphabetical class reference"
	80	section of the reference manual. I find the HTML version to be the
	81	easiest to use: you can browse very quickly through it. Here's how to
	82	read this (very large) reference:<P>
	83
	84	<ol>
	85	<li>Get an overview of the kinds of classes involved. The class names
	86	will tell you a lot about what each class does. Open some of the
	87	classes, in particular, wxApp (the main application object), wxFrame,
	88	wxControl (the base class for all controls) and one or two controls,
	89	like wxButton.
	90
	91	<li>When scanning a class for the first several times, read the
	92	introductory remarks and quickly scan the list of methods of the class
	93	to get a general idea about what kinds of operations can be done to
	94	objects of the class. You are not looking for detail at this stage,
	95	just for the big picture. In particular, what classes exist and how do
	96	they work together.
	97
	98	<li>Pay particular attention to the classes from which a class is
	99	derived. For example, a button (an object of type wxButton) is derived
	100	from the wxControl, wxWindow, wxEvtHandler and wxObject classes. What
	101	does this mean? It means that a button _is_ a control, and a button
	102	_is_ a window, and a button _is_ an event handler and a button _is_ an
	103	object. So you must understand the parent classes of an object to
	104	understand the object itself.
	105
	106	For example, if b is a button you can invoke b.m for any of method m of
	107	the wxControl, wxWindow, wxEvtHandler or wxObject classes. You are not
	108	limited to just the methods of wxButton! This is one of the keys of
	109	object oriented programming.
	110	</ol>
	111
	112	Some other tips:<P>
	113
	114	Read some sample code. You will find that almost none of the C++
	115	language is actually being used; it's just endlessly creating objects
	116	and then calling methods using those objects.<P>
	117
	118	Learn as much as you can about the String class; after using a good
	119	String class you'll never want to use C's string functions again.
fc2171bd	120	wxWidgets contains other nifty utility classes as well.<P>
f6bcfd97 BP	121
	122	The application class, wxApp, contains the main event loop. Learn about
	123	event handling and event tables (reading sample code will help). Almost
	124	everything in this kind of application framework happens as the result
	125	of an event and your app is essentially doing nothing but responding to
	126	events. Having the event loop written for you is a major, major
	127	benefit.<P>
	128
	129	I hope this helps. Perhaps we can work together in learning about
fc2171bd JS	130	wxWidgets. Please feel free to ask me any questions you might have. If
fc2171bd JS	131	I've made any blunders in this posting I hope the wxWidgets experts will
f6bcfd97 BP	132	correct me gently.<P>
	133
	134	Edward<BR>
	135	--------------------------------------------------------------------<BR>
	136	Edward K. Ream email: edream@tds.net<BR>
	137	Leo: Literate Editor with Outlines<BR>
	138	Leo: http://personalpages.tds.net/~edream/front.html<BR>
	139	--------------------------------------------------------------------<P>
	140
	141	</font>
	142
	143	</body>
	144	</html>