Two Tkinter questions (long)

[Aaron Ginn]

I have two questions about Tkinter.  First, how do you supress a
command that is executed by a button when a widget is created?  I'm
trying to create a file browser with three buttons, an OK button which
applies the selection, a filter button which filters the current
directory for a matching pattern and a cancel button which does the
obvious.  The problem is that when I create the file browser in a
toplevel widget, the command that my buttons are supposed to execute
are executed immediately.  For instance, here's a portion of code:

class FileBrowser:

    def __init__(self, obj, dir):

	self.list_of_files = []
	self.list_of_dirs  = []

	# Set the default directory to dir.
	self.filter_directory = StringVar()
	self.filter_directory.set(dir)

	# Set defualt filter value to all files in dir.
	self.filter_pattern = StringVar()
	self.filter_pattern.set('*')

	self.selection_value = StringVar()
	self.selection_value.set('None')

	self.top = Toplevel()

< SNIP a lot of wigdets for brevity >

	self.Filter = Button(self.button_frame, text = 'Filter', \
		      command = self.do_filter())
	self.Filter.pack(side = LEFT, padx = 10)


The filter button is bound to a method called do_filter which is as
follows:


    def do_filter(self):
	"""
	Method that generates a list of files and a list of
	directories in a directory given a filter pattern,
	and add them to a listbox for each.
	"""

	filter_path = '%s/%s' %(self.filter_directory.get(), self.filter_pattern.get())
	files_matching_pattern = glob.glob(filter_path)

	# Clear the listboxes
	self.filelist.delete(0,END)
	self.dirlist.delete(0,END)

	# Add . and .. to list of directories.
	self.dirlist.insert(END, '.')
	self.dirlist.insert(END, '..')

	# Fill the listboxes
	for file in files_matching_pattern:
	    [head, tail] = os.path.split(file)
	    if os.path.isfile(file):
		self.filelist.insert(END, tail)
		self.list_of_files.append(tail)
	    elif os.path.isdir(file):
		self.dirlist.insert(END, tail)
		self.list_of_dirs.append(tail)


This works fine, but the command is executed as soon as the widget is
created, and then I can't execute it again.  It is as if the script
has been executed and terminated but the GUI still exists.  Why is the
command that button is bound to executing before I invoke the
button?

This leads to my second question.  I put the command in a lambda
statement to supress it's execution.  When I do this the filter
function works great, and I can execute it multiple times.  However,
when I try to bind the method do_filter to an Event, the event fails
with the following error:


coronado <189> semiDRC.gui -gui
Exception in Tkinter callback
Traceback (innermost last):
  File "/home/ginn/python_tk/lib/python1.5/lib-tk/Tkinter.py", line 764, in __call__
    return apply(self.func, args)
  File "/home/ginn/bin/semiDRC.gui", line 450, in <lambda>
    self.filter_entry.bind('<Return>', lambda s=self: s.do_filter())
AttributeError: do_filter


The bind statement is


self.filter_entry.bind('<Return>', lambda s=self: s.do_filter())


Is there a problem with binding an event to a lambda function?  How do
you do this?  I'm very confused right now!

Aaron

-- 
Aaron J. Ginn                     Motorola SPS
Phone: (480) 814-4463             SemiCustom Solutions
Fax:   (480) 814-4058             1300 N. Alma School Rd.
mailto:aaron.ginn at motorola.com    Chandler, AZ 85226