What is intvar?

[W. eWatson]

I'm looking at someone's code in which invar() is used fairly often.
Apparently, it's a Tkinter method. Here's a use:
def body(self,master):
self.title("Display Settings")

self.colorVar = IntVar()
Radiobutton( master, text="Gray Scale",
value=1, variable=self.colorVar).grid(row=0, sticky=W)
Radiobutton( master, text="Pseudo Color",
value=2, variable=self.colorVar).grid(row=1, sticky=W)
...

What is the need for this use? It looks like some sort of initialization for
a widget.

I've scoured the internet with Google, and have yet to find a simple
explanation of what it's used for.
--
W. eWatson

(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

Web Page: <www.speckledwithstars.net/>

 

[Chris Rebert]

I'm looking at someone's code in which invar() is used fairly often.
Apparently, it's a Tkinter method. Here's a use:
def body(self,master):
self.title("Display Settings")

self.colorVar = IntVar()
Radiobutton( master, text="Gray Scale",
value=1, variable=self.colorVar).grid(row=0, sticky=W)
Radiobutton( master, text="Pseudo Color",
value=2, variable=self.colorVar).grid(row=1, sticky=W)
...

What is the need for this use? It looks like some sort of initialization for
a widget.

I've scoured the internet with Google, and have yet to find a simple
explanation of what it's used for.

Search for IntVar on http://docs.python.org/library/tkinter.html and
read the enclosing section.
I think it's basically used to propagate changes to the GUI and
convert values (in this case, ints) between Python and Tk.

Cheers,
Chris

 

[Rhodri James]

I'm looking at someone's code in which invar() is used fairly often.
Apparently, it's a Tkinter method. Here's a use:
def body(self,master):
self.title("Display Settings")

self.colorVar = IntVar()
Radiobutton( master, text="Gray Scale",
value=1, variable=self.colorVar).grid(row=0,
sticky=W)
Radiobutton( master, text="Pseudo Color",
value=2, variable=self.colorVar).grid(row=1,
sticky=W)
...

What is the need for this use? It looks like some sort of initialization
for a widget.

Chris has already pointed you to the Tkinter documentation, which is a
good start but a little less than clear in places.

What your example code does is to associate self.colorVar with the set
of radio buttons. This isn't just initialisation, it's a full reflection
of the current state.

self.colorVar.get() returns the "value" parameter that you gave to the
radio button which is currently selected (so, for example, if it returns
1 you know that the "Grey Scale" button is the one selected). Similarly
self.colorVar.set(n) selects whichever radio button has the "value" which
matches n (so self.colorVar.set(2) selects the "Pseudo Color" button).

IntVar and StringVar (and DoubleVar if you must are basically the
easy way of dynamically reading and changing the values in various
entry widgets, the text on buttons, and so on.

 

[r]

here is a good explanation of control vars:
http://infohost.nmt.edu/tcc/help/pubs/tkinter/control-variables.html

Here are 3 great Tkinter refernces in order:
http://infohost.nmt.edu/tcc/help/pubs/tkinter/
http://effbot.org/tkinterbook/
http://www.pythonware.com/library/tkinter/introduction/

 

[W. eWatson]

here is a good explanation of control vars:
http://infohost.nmt.edu/tcc/help/pubs/tkinter/control-variables.html

Here are 3 great Tkinter refernces in order:
http://infohost.nmt.edu/tcc/help/pubs/tkinter/
http://effbot.org/tkinterbook/
http://www.pythonware.com/library/tkinter/introduction/

Thanks to all for the reference and tips.

--
W. eWatson

(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

Web Page: <www.speckledwithstars.net/>

 

[W. eWatson]

Thanks to all for the reference and tips.

tkinterbook is easy to follow, but it seems to have been abandoned in 2005.
Did it appear in another guise somewhere else?

--
W. eWatson

(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

Web Page: <www.speckledwithstars.net/>

 

[Steve Holden]

tkinterbook is easy to follow, but it seems to have been abandoned in
2005. Did it appear in another guise somewhere else?

There hasn't been a lot of development on Tkinter in the intervening
period. It's a mature system, so there has been no need to update the
documentation.

regards
Steve

 

[W. eWatson]

There hasn't been a lot of development on Tkinter in the intervening
period. It's a mature system, so there has been no need to update the
documentation.

regards
Steve

Unfortunately, the author seems to have stopped mid-stream. I see a fair
number of FIXMEs in it. It looks like the New Mexico pdf is a fitting
replacement. Perhaps Intro to Tkinter should be scrapped?

Another of the author's writings, on PIL, looks good as a pdf, but is
missing a TOC. Maybe some pdf knowledgeable person knows how to generate one
easily.

--
W. eWatson

(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

Web Page: <www.speckledwithstars.net/>

 

[r]

W. eWatson,

I contacted the author of New Mexico Techs "Introduction to Tkinter" a
couple of weeks ago. He is going to update the reference material with
a few missing widgets and some info on Photo and Bitmap classes. I
really love the NMT layout and use it quite often. Fredricks
Tkinterbook is more detail but lacking in navigation. I swing back and
forth between both sites.

 

[W. eWatson]

W. eWatson,

I contacted the author of New Mexico Techs "Introduction to Tkinter" a
couple of weeks ago. He is going to update the reference material with
a few missing widgets and some info on Photo and Bitmap classes. I
really love the NMT layout and use it quite often. Fredricks
Tkinterbook is more detail but lacking in navigation. I swing back and
forth between both sites.

Good. Thanks. I think Lundh might have taken his material to book form.

I might be repeating myself here, but If anyone has pdf experience, and
could provide page numbers and maybe a TOC for some of Lundh's
contributions, that would be helpful.

--
W. eWatson

(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

Web Page: <www.speckledwithstars.net/>

 

[r]

I might be repeating myself here, but If anyone has pdf experience, and
could provide page numbers and maybe a TOC for some of Lundh's
contributions, that would be helpful.

Did you try this one?
http://effbot.org/tkinterbook/tkinter-index.htm

here is the older less detailed version:
http://www.pythonware.com/library/tkinter/introduction/

neither are PDF thought. But NMT has a PDF download here:
http://infohost.nmt.edu/tcc/help/pubs/tkinter/