Python fruit basket program with no indentation
- From: Jamal Mazrui <empower@xxxxxxxxx>
- To: ProgrammingBlind@xxxxxxxxxxxxx
- Date: Tue, 7 Apr 2009 14:16:50 -0400 (EDT)
From the archive
http://EmpowermentZone.com/py_fruit.zip
This fruit basket program is written in Python 2.5, available at
http://python.org
with wrappers for WxWidgets 2.8, available at
http://wxPython.org
and an executable builder available at
http://py2exe.org
This updates the previous archive with an experimental approach that
completely avoids the Python indentation requirement. The source code is
in the file no_indent.py, which may be run in console mode with the Python
interpreter, using the batch file RunNo_Indent.bat. That code is also
used to build the stand-alone, Windows executable no_indent.exe, using the
batch file RunSetup.bat and script setup.py.
For convenient review by email, a copy of no_indent.py is also pasted
below.
Jamal
"""
Fruit basket program in Python with no indentation
Public domain by Jamal Mazrui
April 7, 2009
The indentation requirement of the Python programming language aids
its visual readability, but poses perhaps its biggest challenge to
blind users of speech output. The challenge is manageable, as
demonstrated by a number of successful blind programmers. Techniques
typically focus on ways of efficiently querying or adjusting
indentation with speech in order to follow the logical structure of
code.
This sample program instead uses techniques that avoid the need for
indentation, itself, by exploiting other features of the language.
The Python code is valid and functional, though not conventional in
style.
The first technique defines a function for executing a block of
statements in an in-line event handler -- also called an 'anonymous
delegate.' The multiple lines of code are enclosed in a triple
quoted string. At runtime, the custom execute function is called by
the built-in lambda function, which must be passed an expression
rather than statement(s).
Within event handling code, parts of a compound statement are put on
a single line. In the Add handler, the 'or' keyword is used to
combine sequential tasks that each return False. In the Delete
handler, a semicolon (;) is used, as well as an in-line 'if'
expression.
The resulting program implements the criteria of a fruit basket
program in Python without needing any indentation. Moreover, the
code is more scripting-like because all variables defined are
accessible globally, and no explicit class structures are needed.
The techniques are not necessarily recommended, but they hopefully
show additional possibilities for overcoming the indentation
requirement of a popular language.
"""
# Import wxWidgets package
import wx
# Define function that executes a block of statements
def execute(sCode): exec sCode
# Initialize program and dialog
app = wx.PySimpleApp()
dlg = wx.Dialog(parent=None, title='Fruit Basket')
# Handle Close event
dlg.Bind(wx.EVT_CLOSE, lambda event: execute("""
if wx.MessageBox('Exit program?', 'Confirm', wx.YES_NO) == wx.YES:
dlg.Destroy()
"""))
# Define first row of controls
lblFruit = wx.StaticText(parent=dlg, label='&Fruit:')
txtFruit = wx.TextCtrl(parent=dlg)
btnAdd = wx.Button(parent=dlg, label='&Add')
# Handle Add event
btnAdd.SetDefault()
btnAdd.Bind(wx.EVT_BUTTON, lambda event: execute("""
sFruit = txtFruit.GetValue()
if len(sFruit ) == 0: wx.MessageBox('No fruit to add!', 'Alert')
else: lstBasket.Insert(sFruit, 0) or lstBasket.SetSelection(0) or
txtFruit.Clear()
"""))
# Define second row of controls
lblBasket = wx.StaticText(parent=dlg, label='&Basket:')
lstBasket = wx.ListBox(parent=dlg)
btnDelete = wx.Button(parent=dlg, label='&Delete')
# Handle Delete event
btnDelete.Bind(wx.EVT_BUTTON, lambda event: execute("""
iIndex = lstBasket.GetSelection()
iCount = lstBasket.GetCount()
if iIndex == -1: wx.MessageBox('No fruit to delete!', 'Alert')
else: lstBasket.Delete(iIndex); lstBasket.SetSelection(min(iIndex,
iCount)) if iCount > 1 else None
"""))
# Define layout sizer
sizer = wx.FlexGridSizer(cols=3, hgap=6, vgap=8)
for widget in (lblFruit, txtFruit, btnAdd, lblBasket, lstBasket,
btnDelete): sizer.Add(widget)
dlg.SetSizerAndFit(sizer)
# Activate dialog and run program
dlg.Show()
app.MainLoop()
__________
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