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  17 How to learn wxWidgets programming
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  24
  25 The following is a response by Edward Ream to a common question,
  26 "What's the best way to learn wxWidgets [and C++]?".<P>
  27
  28 Date: Sun, 04 Jun 2000 14:37:06 -0500<BR>
  29 From: "Edward K. Ream" <edream@tds.net> <BR>
  30 To: wx-users@wxwidgets.org<BR>
  31 Subject: Re: [wx-users] How to learn using wx-windows <BR>
  32 Reply-To: wx-users@wxwidgets.org<P>
  33
  34 &gt; Reading the Linux Journal article on wxpython, and having used wxclips<BR>
  35 &gt; I got interested in wxwidgets as a development interface. However, the<BR>
  36 &gt; programming experience I got is old, and from a former generation (For-<BR>
  37 &gt; tran). I'd like to refresh my experience and start in C++.  Will<BR>
  38 &gt; wx-windows be a very high step to take?<P>
  39
  40 I'm new to wxWidgets myself, but I'd like to answer this question
  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
  50 simply, more simply than C.  With a system like wxWidgets you will be
  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,
  57 by Stanley B. Lippman.  (Lippman was one of the C++ honchos at Bell
  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
  64 Application frameworks such as wxWidgets are organized around a set of
  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.
 120 wxWidgets contains other nifty utility classes as well.<P>
 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
 130 wxWidgets.  Please feel free to ask me any questions you might have.  If
 131 I've made any blunders in this posting I hope the wxWidgets experts will
 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:&#47;&#47;personalpages.tds.net/~edream/front.html<BR>
 139 --------------------------------------------------------------------<P>
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