[pygtk] help with script

[Jody Steele]

Hi Christopher,

One way, and a fairly simple solution, would be to call convert_to_celcius  
immediately after initializing your object (self.convert_to_celcius(adj1)  
in __init__ after setting up the scroll bar).  That should do what you  
need.  It's been a while since I've used Python, but that should work.

Cheers,

Jody Steele

On Mon, 26 Jun 2006 13:10:04 -0400, Christopher Spears  
<cspears2002 at yahoo.com> wrote:

> Here is a script that I wrote:
>
> #!/usr/bin/python
>
> import pygtk
> pygtk.require('2.0')
> import gtk
>
> def scale_set_default_values(scale):
> 	scale.set_update_policy(gtk.UPDATE_CONTINUOUS)
> 	scale.set_digits(1)
> 	scale.set_value_pos(gtk.POS_LEFT)
> 	scale.set_draw_value(True)
> 	scale.set_sensitive(True)
> 	
> class Conversion_GUI:
> 	
> 	def convert_to_celsius(self, adj):
> 		self.degC = (adj.value - 32)/1.8
> 		return self.degC
> 		
> 	
> 	def print_celsius(self, widget):
> 		print "Degrees Celsius: %.2f" % self.degC
> 		
> 		
> 	def __init__(self):
> 		self.window = gtk.Window(gtk.WINDOW_TOPLEVEL)
> 		self.window.connect("destroy", lambda w:
> gtk.main_quit())
> 		self.window.set_title("Convert to Celsius")
> 		self.window.set_default_size(200,240)
> 		
> 		box1 = gtk.VBox(False, 0)
> 		self.window.add(box1)
> 		
> 		box2 = gtk.HBox(False, 10)
> 		box2.set_border_width(10)
> 		box1.pack_end(box2, True, True, 0)
> 		
> 		box3 = gtk.HBox(False, 10)
> 		box3.set_border_width(10)
> 		box1.pack_end(box3, True, True, 0)
> 		
> 		adj1 = gtk.Adjustment(32.0, 32.0, 213.0, 0.1, 1.0,
> 1.0)
> 		self.vscale = gtk.VScale(adj1)
> 		self.vscale.set_size_request(20, 300)
> 		scale_set_default_values(self.vscale)
> 		box1.pack_start(self.vscale, True, True, 0)
> 		
> 	
> adj1.connect("value_changed",self.convert_to_celsius)
> 		
> 		quit_button = gtk.Button("Quit")
> 		quit_button.connect("clicked", lambda
> w:gtk.main_quit())
> 		convert_button = gtk.Button("Convert")
> 		convert_button.connect("clicked",
> self.print_celsius)
> 		box3.pack_start(convert_button, True, True, 0)
> 		box2.pack_start(quit_button, True, True, 0)
> 		
> 		self.vscale.show()
> 		convert_button.show()
> 		quit_button.show()
> 		box3.show()
> 		box2.show()
> 		box1.show()
> 		self.window.show()
> 		
> 	def main(self):
> 		gtk.main()
> 		return 0
> 	
> if __name__ == '__main__':
> 	convert = Conversion_GUI()
> 	convert.main()
>
> The script creates a gui with a vertical scrollbar and
> two buttons (Convert and Quit).  Using the scrollbar,
> I can select a value in degrees Fahrenheit.  Then I
> can convert this and print it to the screen using the
> Convert button.  However, when I first start the
> program and press the convert button without moving
> the scrollbar, I get an error message:
>
> Traceback (most recent call last):
> File "C:\Documents and Settings\Christopher Spears\My
> Documents\programming\PythonScripts\convertCelsius.py",
> line 22, in print_celsius
>     print "Degrees Celsius: %.2f" % self.degC
> AttributeError: Conversion_GUI instance has no
> attribute 'degC'
>
> My guess is since the scrollbar has not been moved yet
> degC has not been computed, which causes the error
> when Convert is pressed.  Can someone advise me on a
> solution?  Sorry if this is a basic question.  I'm new
> to pygtk.
>
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>



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