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1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 2 "http://www.w3.org/TR/1999/REC-html401-19991224/loose.dtd"> 3<html lang="en"> 4<head> 5 <title>One Day of MacPython IDE Toying</title> 6 <link rel="SHORTCUT ICON" href="../pythonsmall.gif"> 7 <META NAME="AppleIcon" CONTENT="../pythonsmall.gif"> 8</head> 9<body bgcolor="#ffffff"> 10 <h1>One Day of MacPython IDE Toying</h1> 11 <table> 12 <tr> 13 <td> 14 <img src="IDE.gif" alt=""> 15 </td> 16 <td> 17 <p>This document gives a very basic introduction to the 18 MacPython <b>I</b>ntegrated <b>D</b>evelopment <b>E</b>nvironment (IDE) on Mac OS. It was 19 written specifically for MacPython 2.3 on Mac OS X, but most of 20 it is applicable to MacPython-OS9 too. It is based on 21 <a href="http://www-hkn.eecs.berkeley.edu/~dyoo/python/idle_intro/">"One 22 Day of IDLE Toying"</a> by Danny Yoo, which you should read if 23 you want to use the cross-platform IDLE Python development 24 environment.</p> 25 26 </td> 27 </tr> 28 </table> 29 <hr> 30 <br style="page-break-after: always"> 31 32<p>Ok, let's assume that we've already installed Python. (If not, we can 33visit: <a href="http://www.cwi.nl/~jack/macpython.html">http://www.cwi.nl/~jack/macpython.html</a> 34or <a href="http://python.org">http://python.org</a> 35and download the most recent Python interpreter. Get the Mac OSX binary 36installer.) The first thing we'd like to do is actually start running it! 37We can do this by opening up the IDE, which should be in Applications 38under the newly-created MacPython program folder: </p><p><img 39src="loading_ide.gif" border=1 alt="image of IDE icon"></p> 40 41<hr><br style="page-break-after: always"> 42 43<p>The IDE starts up and shows an interactive window: </p> 44<p><img src="new_ide_window.gif" alt="image of new window"></p> 45 46<p>If the window does not show up (because you have run the IDE before 47and closed it: it remembers that between runs) open it with the <tt>Windows->Python Interactive</tt> 48menu entry. </p> 49 50<p>This is the interactive window to the IDE, it allows us to enter 51commands directly into Python, and as soon as we enter a command, 52Python will execute it and spit its result back to us. We'll be 53using this interactive window a lot when we're exploring Python: it's 54very nice because we get back our results immediately. If it helps, 55we can think of it as a very powerful calculator.</p> 56 57<hr><br style="page-break-after: always"> 58 59<p>Let's try something now! As per tradition, let's get Python to say 60the immortal words, "Hello World". <img src="hello_world.gif" 61border=1 alt="image of hello world program"></p> <p>Those '<tt>>>></tt>' signs act as a prompt 62for us: Python is ready to read in a new command by giving us that 63visual cue. Also, we notice that as we enter commands, Python will 64give us its output immediately. 65</p> 66 67<hr><br style="page-break-after: always"> 68 69<p>Ok, this seems pretty simple enough. Let's try a few more 70commands. If we look below:</p> 71 72<p><img src="simple_commands.gif" border=1 alt="image of command window"></p> 73 74<p>we'll see the result of running a few more commands. Don't worry 75too much about knowing the exact rules for making programs yet: the 76idea is that we can experiment with Python by typing in commands. If 77things don't work, then we can correct the mistake, and try it 78again.</p> 79 80<p>If you got to this point, you now know enough to start playing 81around with Python! Crack open one of the tutorials from the <a 82href="http://python.org/doc/Newbies.html">Python For Beginners</a> web 83page, and start exploring with the interpreter. No time limit here. *grin*</p> 84 85<hr><br style="page-break-after: always"> 86 87<p>Now that we've paddled long enough, we might be asking: ok, this is 88neat, but if we close down Python and start it up again, how do we get 89the computer to remember what we typed?</p> 90 91<p>The solution is a little subtle: we can't directly save what's in 92the interpreter window, because it will include both our commands and 93the system's responses. What we'd like is to make a prepared file, 94with just our own commands, and to be able to save that file as a 95document. When we're in the mood, we can later open that file and 96"run" Python over it, saving us the time of retyping the whole 97thing over again.</p> 98 99<p>Let's try this. First, let's start with a clean slate by opening 100up a new window.</p> 101 102<p><img src="making_new_window.gif" border=1 alt="image of making new window"></p> 103 104<p>Here's the result of that menu command:</p> 105 106<p><img src="new_window_made.gif" border=1 alt="image of new window"></p> 107 108<p>We notice that there's nothing in this new window. What this means 109is that this file is purely for our commands: Python won't interject 110with its own responses as we enter the program, that is, not until we 111tell it to. This is called an edit window, and it is very similar 112to edit windows in other editors such as TextEdit or BBEdit.</p> 113 114<hr><br style="page-break-after: always"> 115 116<p>What we wanted to do before was save some of the stuff we had 117tried out on the interpreter window. Let's do that by typing (or 118copy/pasting) those commands into our edit window.</p> 119<p><img src="entering_in_new_window.gif" border=1 alt="image of entering commands"></p> 120 121<p>Ok, we're done with copying and pasting. 122One big thing to notice 123is that we're careful to get rid of the "<tt>>>></tt>" 124prompts because they're not really part of our program. The 125interpreter uses them just to tell us that we're in the interpreter, 126but now that we're editing in a separate file, we can remove the 127artifacts that the interpreter introduces. 128I have added 129an extra empty print statement so our output ends with a newline. 130</p> 131 132<hr><br style="page-break-after: always"> 133 134<p>Let's save the file now. The Save command is located under the <tt>File</tt> menu:</p> 135<p><img src="saving_edited_file.gif" border=1 alt="image of saving file"></p> 136 137 138<hr><br style="page-break-after: always"> 139 140<p>Now that we've saved the program, how do we run the program? Use the 141Run All button at the top of the editing window, or the equivalent 142menu command <tt>Python->Run Window</tt>. The output will appear in a new 143window called Output Window. </p> 144 145<p>By the way, one thing to notice is that I made a typo: I didn't 146quite copy exactly what I had entered in the interpreter window 147before. Does this affect things?</p> 148 149<p><img src="syntax_error.gif" border=1 alt="image of syntax error"></p> 150 151<p>Ooops. Here is an example of what Python calls a "syntax error". 152Python sees that we made a typo, and warns us to take a much closer 153look at our program. The designers of Python feel that having the 154system point out the error is better than trying to guess at what the 155programmer meant. Press the Edit button and you will be brought to 156the trouble spot. </p> 157 158<p>Python is often perceptive enough to direct us toward the problem, 159and in this case, it's telling us that we forgot to put something at 160the end of this line. In this case, we need to add a 161quotation mark at the end. Let's add that in now.</p> 162 163<p>Other errors, which usually occur later, when your program has 164already done something, result in a different dialog that allows you 165to look at variables and such in addition to showing you where 166the error occurred. </p> 167 168<hr><br style="page-break-after: always"> 169 170<p>Ok, let's say that we fixed that silly typo. Let's try to run the 171program again. This gives us a new window, the Output window, showing 172the output of our program:</p> 173<p><img src="output_window.gif" border=1 alt="image of output window"></p> 174 175<hr><br style="page-break-after: always"> 176 177<p>As we play with Python, we'll find ourselves "switching modes" 178between the Interpreter window and the edit window. However, 179if we try anything more complicated than two or three lines it 180is often a good idea to work in an edit window. Align 181your edit and output window such that you can see them at the same time.</p> 182 183<p>This is pretty much all we need to know about the MacPython IDE to actually do 184interesting things. There is a lot more to the IDE, here is a quick 185breakdown of things to see and explore:</p> 186 187<ul> 188 <li>All sorts of edit commands such as find and replace can be 189 used in the editor windows. See the <tt>Edit</tt> menu.</li> 190 191 <li>The bottom of the edit window has the scrollbar, but at the 192 left are two navigation devices: a line number box that you can type 193 numbers into to quickly go to a specific place, and a popup menu 194 that lists all classes, functions and methods in your file.</li> 195 196 <li>Above the vertical scrollbar you find another popup menu, this 197 influences how the Run command works. You should try the debugger 198 some time! If you do, and you wonder what the new small column on 199 the left of your script is: you can click in it to make Python stop 200 when it reaches this line so you can inspect things. The profiler 201 is also nifty: it shows you where your program is spending its time.</li> 202 203 <li>The module browser (<tt>Python->Module Browser</tt>) shows you all Python 204 modules currently loaded. You can look at the contents of the module with 205 Browse... and (for modules written in Python) at the source with Source...</li> 206 207 <li>The Package Manager (under the <tt>File</tt> menu, also available as a 208 separate application) allows you to easily install Python extension packages 209 for all sorts of things: scientific computation, image processing, 210 building user interfaces and more. </li> 211 212 <li>The <tt>Help</tt> menu gives you quick access to both the Python documentation, 213 if you have installed it with the Package Manager, and the Apple Developer 214 documentation. </li> 215 216 <li>The <tt>File->Save as Applet</tt> menu command saves your script as a MacOSX 217 application. This allows you to create a script that you can drop files on, 218 and much more. The IDE itself is such an applet, completely written in Python. </li> 219 220</ul> 221</body> 222</html>