From 024a387f89cd4c08b67ffca0d8df311a34cc8a49 Mon Sep 17 00:00:00 2001 From: Jack Jansen Date: Thu, 18 Jul 1996 16:07:05 +0000 Subject: - Added a file dialog example - Added pointers to library documentation --- Mac/Demo/example0.html | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) create mode 100644 Mac/Demo/example0.html (limited to 'Mac/Demo/example0.html') diff --git a/Mac/Demo/example0.html b/Mac/Demo/example0.html new file mode 100644 index 0000000000..c0336a56bf --- /dev/null +++ b/Mac/Demo/example0.html @@ -0,0 +1,75 @@ +Using python to create Macintosh applications, part zero + +

Using python to create Macintosh applications, part zero

+
+ +This document will show you how to create a simple mac-style +application using Python. We will glance at how to use file dialogs and +messages.

+ +Our example program checktext.py asks +the user for a text file and checks what style end-of-lines the file has. +This may need a little explanation: ASCII text files are almost identical +on different machines, with one exception: +

+ +Let us have a look at the program. The first interesting statement in the main +program is the call to macfs.PromptGetFile. This is one of the routines +that allow you to ask the user to specify a file. You pass it one required +argument, the prompt string. There are up to four optional MacOS file type arguments +you can pass, as 4-byte strings. Specifying no file +type will allow the user to select any file, specifying one or more types restricts +the user to files of this type. File types are explained in most books on the Mac.

+ +PromptGetFile returns two values: an FSSpec object and a +success indicator. The FSSpec object is the "official" MacOS way of specifying a +file, more on it later. The success indicator tells you whether the user clicked OK +or Cancel. In the event of Cancel we simply exit back to the finder.

+ +PromptGetFile has a number of friends that do similar things: +

+All routines return an FSSpec and a success indicator.

+ +There are many things you can do with FSSpec objects (see the +macfs section in the +Python Library Reference +for details), but passing them to open is not +one of them. For this, we first have to convert the FSSpec object to a pathname, with +the as_pathname method. This returns a standard MacOS-style pathname with +colon-separated components. This can then be passed to open. Note that +we call open with mode parameter 'rb': we want to read the file in binary +mode. Python, like C and C++, uses unix-style line endings internally and opening a +file in text mode ('r') would result in conversion of carriage-returns to +linefeeds upon reading. This is something that Mac and DOS programmers are usually aware +of but that never ceases to amaze unix buffs.

+ +After we open the file we attempt to read all data into memory. If this fails we use +EasyDialogs.Message to display a message in a standard dialog box and exit. +The EasyDialogs module has a few more useful simple dialog routines, more on that in +example 1.

+ +The rest of the code is pretty straightforward: we check that the file actually contains +data, count the number of linefeeds and returns and display a message with our guess of the +end-of-line convention used in the file.

+ +The example0 folder has three text files in Mac, Unix and DOS style +for you to try the program on. After that, you can continue with example 1 +or go back to the index to find another interesting topic.

+ +

+Jack Jansen, +jack@cwi.nl, 18-July-1996. + -- cgit v1.2.1