Living Code

I’ll be presenting on Renaissance, OS X, and Python at the VanX meeting at 6:30 p.m. on Thursday, December 16th. By then I should have a lot more programs and utilities to show.

Nicola Pera has done a great job building Renaissance, and has worked hard to document it well. The manual is clear and easy to follow, but is not complete yet. He invited me to help with the documentation, and I’ve found the source code easy enough to read that I might do that (Objective-C is actually quite Pythonic), but it’s been years since I’ve hacked LaTeX and I’d rather spend my time posting examples of working code. So for now I’ll just stick my notes here about the Renaissance elements which have not yet been documented in the manual.

<browser />

    titled="yes|no" (default: no)

    allowsBranchSelection="yes|no" (default: yes)

    allowsEmptySelection="yes|no" (default: no)

    allowsMultipleSelection="yes|no" (default: no)

    takesTitleFromPreviousColumn="yes|no" (default: yes)

    separatesColumns="yes|no" (default: yes)

    acceptsArrowKeys="yes|no" (default: yes)

    hasHorizontalScrollbars="yes|no" (default: no)

    doubleAction="[selector]"

    minColumnWidth="[number]"

    maxVisibleColumns="[number]"

    matrixClass="[subclass of NSMatrix]"

    cellClass="[subclass of NSCell]"

<colorwell/>

    color="[Color]" (See section 2.3.3.6 of the manual for info on Color attributes)

<form/>

    titleFont="[Font]" (See section 2.3.3.7 of the manual for info on Font attributes)

    titleAlignment="left|right|center"

<label/>

    color="[Color]"

    backgroundColor="[Color]"

    font="[Font]"

    align="left|right|center"

<matrix/> (contains matrixRow elements)

    doubleAction="[Selector]"

<matrixRow/> (contains matrixCell elements)

<matrixCell/>

    title="[String]"

    action="[Selector]"

    editable="yes|no"

    selectable="yes|no"

    tag="(???)" (I'm not sure how tags are used yet)

<outlineView/>

    outlineColumn="[Number]"

<popupButton/> (contains popupButtonItems)

    title="[String]"

    pullsDown="yes|no"

    autoenabledItems="yes|no" (default: yes)

<popupButtonItems/>

    tag="(???)"

    action="[Selector]"

    key="(???)"

    title="[String]"

<scrollView/>

    hasHorizontalScroller="yes|no"

    hasVerticalScroller="yes|no"

    borderType="none|line|bezel|groove"

<secureTextField/>

<splitView/>

    vertical="yes|no"

<tableColumn/>

    identifier="(???)"

    editable="yes|no"

    title="[String]"

    minWidth="[Number]"

    maxWidth="[Number]"

    width="[Number]"

    resizable="yes|no"

<tableView/> (contains tableColumns)

    dataSource="[Outlet]"

    delegate="[Outlet]"

    doubleAction="[Selector]"

    allowsColumnReordering="yes|no"

    allowsColumnResizing="yes|no"

    allowsMultipleSelection="yes|no"

    allowsEmptySelection="yes|no"

    backgroundColor="[Color]"

    drawsGrid="yes|no"

    gridColor="[Color]"

    autosaveName="[String]"

<textField/>

    editable="yes|no"

    selectable="yes|no"

    align="left|right|center"

<textView/> **(Note: Always put a textView inside a scrollView!)**

    editable="yes|no"

    selectable="yes|no"

    richText="yes|no"

    usesFontPanel="yes|no"

    allowsUndo="yes|no"

    usesRuler="yes|no"

    importGraphic="yes|no"

Well, that’s what I have so far. I will try to keep this updated as I learn more, or simply point to the manual as it becomes more complete.

Aaron Hillegass’ book, “Cocoa Programmig for Mac OS X” is a great way to learn Cocoa, Objective-C and Interface Builder, and I highly recommend you buy it to understand OS X programming (of course, you’ll be buying the new, improved Second Edition, and I’m working off the first edition here, so things may not completely match up). In order to demonstrate how compact, yet readable, Renaissance + Python can be, I’m going to convert the example programs from this book. Aaron’s company is called Big Nerd Ranch, and I was trying to find something to show which postings were examples from the book, so readers can follow along, but without implying in any way that Aaron has approved of these conversions in any way, so I’m going to call them the Small Nerd Examples (The small nerd being me).

Note that while you are developing, it is inconvenient to have to build the project every time you touch a file, so you can use python setup.py py2app –alias to build it once, then you can edit your files normally and the changes will be reflected when you run your application. Just remember to re-run this when you add a new file, and to re-run it without the alias flag when you’re building any version to be distributed.

Like the previous example, Hello World, this one contains four files. The setup.py file will look radically similar to the Hello World version. The program itself is simple: A window with two buttons, one which seeds the random number generator with the current time, and another which generates and displays a random number between 1 and 100 in a text field.

MainMenu.gsmarkup

<?xml version="1.0"?>

<!DOCTYPE gsmarkup>

<gsmarkup>

    <objects>

        <menu type="main">

            <menu title="ch02" type="apple">

                <menuItem title="About ch02" action="orderFrontStandardAboutPanel:"/>

                <menuSeparator/>

                <menu title="Services" type="services"/>

                <menuSeparator/>

                <menuItem title="Hide ch02" action="hide:" key="h"/>

                <menuItem title="Hide Others" action="hideOtherApplications:"/>

                <menuItem title="Show All" action="unhideAllApplications:"/>

                <menuSeparator/>

                <menuItem title="Quit ch02" action="terminate:" key="q"/>

            </menu>

            <menu title="Window" type="windows">

                <menuItem title="Minimize Window"

                    action="performMiniaturize:" key="m"/>

                <menuSeparator/>

                <menuItem title="Bring All to Front"

                    action="arrangeInFront:"/>

            </menu>

            </menu>

                <menu title="Help" type="help">

                <menuItem title="ch02 Help" keys="?"/>

        </menu>

    </objects>

</gsmarkup>

MainWindow.gsmarkup

<?xml version="1.0"?>

<!DOCTYPE gsmarkup>

<gsmarkup>

    <objects>

        <window delegate="#NSOwner" resizable="no">

            <vbox>

                <button target="#NSOwner" action="seed"

                    title="Seed random number generator with time"/>

                <button target="#NSOwner" action="generate"

                    title="Generate random number"/>

                <textField editable="no" id="text" align="center"/>

            </vbox>

        </window>

    </objects>

    <connectors>

        <outlet source="#NSOwner" target="text" key="outputNum"/>

    </connectors>

</gsmarkup>

ch02.py

'''

Hillegass Example, Ch. 02

'''

from Foundation import *

from AppKit import *

from Renaissance import *

import random

class AppDelegate(NSObject):

    outputNum = None

    def windowWillClose_(self, notification):

        NSApp().terminate_(self)

    def quit_(self, notification):

        NSApp().terminate_(self)

    def close_(self, notification):

        NSApp().terminate_(self)

    def applicationDidFinishLaunching_(self, notification):

        NSBundle.loadGSMarkupNamed_owner_('MainWindow', self)

    def seed(self):

        random.seed()

    def generate(self):

        self.outputNum.setStringValue_(str(random.randint(1,100)))

def main():

    app = NSApplication.sharedApplication()

    delegate = AppDelegate.alloc().init()

    app.setDelegate_(delegate)

    NSBundle.loadGSMarkupNamed_owner_('MainMenu', delegate)

    NSApp().run()

if __name__ == '__main__': main()

setup.py

'''

Run with:

% python setup.py py2app

or

% python setup.py py2app --alias # while developing

'''

from distutils.core import setup

import py2app

setup(

    data_files = ['MainMenu.gsmarkup', 'MainWindow.gsmarkup'],

    app = ['ch02.py'],

)

OK, this time out we’ve got about 52 lines of XML markup and 44 lines of Python. Of course, the program doesn’t really do much more than Hello World, but we’re getting somewhere. If anyone has questions about the code, or want more explanatory text around the Renaissance markup, please let me know in the comments or by email.

Yesterday I laid out the issues I have with using Interface Builder to create Cocoa applications (whether in Objective-C or Python), and my requirements for a replacement. To sum up, here are the requirements again:

• Declarative
• Simple and powerful
• Able to replace NIB files and Interface Builder
• Text-based, not binary
• Agile for rapid development, adapts to rapidly changing code
• Able to specify simple apps completely, in code, without resorting to pictures or talking the user through mouse gestures

As I hinted at previously, I think I’ve found the tool I was looking for in GNUstep Renaissance, and as an added bonus, it can be used to create applications for Linux, unix, and Windows using the GNUstep framework. So although I’m interested mainly in building applications for OS X, there is still a chance for cross-platform compatibility.

So what does Renaissance look like? It’s and XML format, similar to HTML and Mozilla XUL (but simpler than XUL). Today I will cover how to install Renaissance and set it up to use from PyObjC.

Prerequisites (this is my setup, others may work, but I haven’t tested them).

1. A Mac
2. OS X (10.3)
3. PyObjC (1.1), available from http://pyobjc.sourceforge.net/
4. py2app (0.1.4), available from http://pythonmac.org/wiki/py2app (we’ll use this to build our double-clickable applications)
5. Renaissance framework (0.8), available from http://www.gnustep.it/Renaissance/Download.html (this is the secret sauce)

Once you have the prerequisites installed, you need to make Renaissance available from Python. In your site-packages directory (on my machine this is /System/Library/Frameworks/Python.framework/Versions/2.3/lib/python2.3/site-packages) add a Renaissance directory containing the following file:

__init__.py

import objc, AppKit, Foundation

objc.loadBundle('Renaissance', globals(),

    bundle_path='/Library/Frameworks/Renaissance.framework')

del objc, AppKit, Foundation

Well, that was easy enough. Next up, a Hello World application.

In my last post I promised a Hello World program for PyObjC + Renaissance. If you haven’t got those installed, or aren’t sure, please check out the prerequisites.

We’ll be creating four files, each of which will be a template for upcoming examples. The menus will be defined in MainMenu.gsmarkup, the application window will be in MainWindow.gsmarkup, the application code will be in hello.py, and the py2app build script will be in setup.py. There is no reason that the menus and window have to be separated this way, but it will serve as an example for later, more complex applications, when you’ll want to load in code from multiple files.

MainMenu.gsmarkup

<?xml version="1.0"?>

<!DOCTYPE gsmarkup>

<gsmarkup>

    <objects>

        <menu type="main">

            <menu title="Hello World" type="apple">

                <menuItem title="About Hello World"

                action="orderFrontStandardAboutPanel:"/>

                <menuSeparator/>

                <menu title="Services" type="services"/>

                <menuSeparator/>

                <menuItem title="Hide Hello World" action="hide:" key="h"/>

                <menuItem title="Hide Others" action="hideOtherApplications:"/>

                <menuItem title="Show All" action="unhideAllApplications:"/>

                <menuSeparator/>

                <menuItem title="Quit Hello World" action="terminate:" key="q"/>

            </menu>

            <menu title="Edit">

                <menuItem title="Cut" action="cut:" key="x"/>

                <menuItem title="Copy" action="copy:" key="c"/>

                <menuItem title="Paste" action="paste:" key="v"/>

                <menuItem title="Delete" action="delete:"/>

                <menuItem title="Select All" action="selectAll:" key="a"/>

            </menu>

            <menu title="Window" type="windows">

                <menuItem title="Minimize Window" action="performMiniatureize:"

                key="m"/>

                <menuSeparator/>

                <menuItem title="Bring All to Front" action="arrangeInFront:"/>

            </menu>

        </menu>

    </objects>

</gsmarkup>

MainWindow.gsmarkup

<?xml version="1.0"?>

<!DOCTYPE gsmarkup>

<gsmarkup>

    <objects>

        <window title="Hello World" closable="NO" >

            <vbox>

                <label>Hello World!</label>

                <button title="Click this button to quit" action="terminate:"/>

            </vbox>

        </window>

    </objects>

</gsmarkup>

hello.py

from Foundation import *

from AppKit import *

from Renaissance import *

class MyApplicationDelegate(NSObject):

    def cut_(self, sender):

        pass

    def applicationDidFinishLaunching_(self, notification):

        NSBundle.loadGSMarkupNamed_owner_('MainWindow', self)

def main():

    app = NSApplication.sharedApplication()

    delegate = MyApplicationDelegate.alloc().init()

    app.setDelegate_(delegate)

    NSBundle.loadGSMarkupNamed_owner_('MainMenu', delegate)

    NSApp().run()

if __name__ == '__main__': main()

setup.py

'''

Minimal setup.py example, run with:

% python setup.py py2app

'''

from distutils.core import setup

import py2app

setup(

    data_files = ['MainMenu.gsmarkup', 'MainWindow.gsmarkup'],

    app = ['hello.py'],

)

Commentary

OK, so 80 lines of code may seem excessive for a Hello World program. We could certainly do it in less, perhaps 20 total lines of Python and Renaissance. But what we have here is a complete working Cocoa application which behaves properly to standard keyboard shortcuts, supports services, etc. And that’s not bad for 80 lines of code.