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Name: [002] Ian Ozsvald
Member: 128 months
Authored: 181 videos
Description: I am the co-founder of ShowMeDo (see, author of `The Screencasting Handbook <>`_ and the founder of the professional screencast production company `ProCasts <>`_: .. image:: ...

Error Handling to give user-feedback [ID:253] (12/17)

in series: Python 101 - easygui and csv

(Showmedo is undergoing major changes. To report any problems viewing the videos please email us and include browser and OS specifics. Cheers - Kyran.)

User's need feedback when things don't go to plan. Learn how to develop code which gives useful error messages for the user and which exits gracefully (rather than crashing out with a horrible error).

Our example is based around adding non-numeric data to the csv file which is caught by our justNumbers functions. We also look at rounding-errors with floating point numbers.

Created May 2007, running time 5 minutes.

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Error Handling to give user-feedback (12/17)

3:00 NameError: name 'sys' is not defined

3:50 Suggested pause point

4:30 demo in DOS

5:40 hardcode input from file dialog during testing

Hi Heimskr. Just replace the 'pathtofile = ...' line in my code with kenf's replacement, it should 'just work' for you.


kenf or Ian how or where do you implement the change you suggest? The pathtofile = easygui.fileopenbox(msg="Select File", title="Open",argInitialFile="C:/Documents and Settings/kenf\My Documents/Programs/*.*")

I'm thinking after fileAndPath = ..... But I am a beginner and don't want to develop bed habits or get squirrely ideas planted in my head from the start.


Nice improvement kenf, thanks for sharing.


Instead of hard coding the file location you can use the argInitialFile in easygui, so the program goes straight to the directory. I prefer this because I can change the file I am testing

pathtofile = easygui.fileopenbox(msg="Select File", title="Open",argInitialFile="C:/Documents and Settings/kenf\My Documents/Programs/*.*")

The *.* just lists all the files, or you can enter the actual file name. Just make sure you use forward slashes since the backslashes can cause problems

Do you know what I like best about these videos, is that you do not sugar-coat anything. You speak exactly the way a computer scientist would talk (you are wondering - how else would you talk), but it really helps with my learning process. Great job.

Showmedo is a peer-produced video-tutorials and screencasts site for free and open-source software (FOSS)- with the exception of some club videos, the large majority are free to watch and download.

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Educating the Open-source Community With Showmedo

Although as important as the software it supports, education and documentation are relatively neglected in the Open-source world. Coders love to code, and explaining how best to use or improve the software tends to be deferred or even sidelined.

At Showmedo we believe the community can play a vital role here and also say thanks for the tools and software that make our lives easier. If you have a piece of software you love or a programming langugage you are enthusiastic about, why not make a screencast showing others how to use it? All the stuff you wish you'd been told, the tips, tricks, insights that would have saved you time and frustration.

Screencasting is easier than you think, and we're happy to help you. You can emailus for advice or just use some of the how-to screencasts on the site. This screencasting learning-pathis a good place to start.

Kudos and Thanks for Ian

3 Minute Oveview (What Does Python Look Like?)

simple and informative. you draw me in
70 months ago


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