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For 2021 - online Python 3 training - see ((here)).

Our plans were to retire in summer 2020 and see the world, but Coronavirus has lead us into a lot of lockdown programming in Python 3 and PHP 7.
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Read from a URL resource with error trapping
Exceptions example from a Well House Consultants training course
More on Exceptions [link]

This example is described in the following article(s):
   • Python - fresh examples from recent courses - [link]

This example references the following resources:
http://www.wellho.net/robots.txt

Source code: grabot.py Module: Y109

""" urllib allows you to open a remote URL and handle the data as if it was
a file, since the object returned from a urllib.urlopen shares many method
names with file handling. However, you're strongly recommended to trap
exceptions as we have done in this example to handle cases where the remote
server is not available or the file you're requesting from there is no longer
available. """


import urllib

try:
        datasource = urllib.urlopen("http://www.wellho.net/robots.txt")
        aok = 1
except:
        print "Can't reach resource"
        aok = 0

if aok:
   while 1:
        line = datasource.readline()
        if line == "": break

# Python's str.partition method splits a string into three at a given seperator
# - bit before
# - separator
# - bit after
# If the separator does not match, everything is placed in the "bit before" posn
# ** really useful for stripping comments!

        before, at, after = line.partition("#")
        info = before.strip()

        if info:
                print info

""" Sample results

wizard:pyoo graham$ python grabot.py
User-agent: *
Disallow: /cgi-bin/
Disallow: /net/unique.html
Disallow: /happens/
Disallow: /resources/mywellho.html
Disallow: /net/search.php4
Disallow: /demo/poc01.php?item
Disallow: /illust/
Disallow: /net/recents.html
Disallow: /net//
Disallow: /resources//
Disallow: /short/
Disallow: /share/e107
Disallow: /share/skin
Disallow: /share/zboard
Disallow: /share/component
Disallow: /share/bbs
Disallow: /share/admin
Disallow: /share/modules
Disallow: /resources/maps.htm
Disallow: /net/maps.htm
Disallow: /wiltshire/index.php4
Disallow: /share/index.php4
Disallow: /overview
Disallow: /demo/pflog
User-agent: TurnitinBot
Disallow: /
wizard:pyoo graham$ """


Learn about this subject
This module and example are covered on the following public courses:
 * Learning to program in Python
 * Python Programming
 * Intermediate Python
Also available on on site courses for larger groups

Books covering this topic
Yes. We have over 700 books in our library. Books covering Python are listed here and when you've selected a relevant book we'll link you on to Amazon to order.

Other Examples
This example comes from our "Exceptions" training module. You'll find a description of the topic and some other closely related examples on the "Exceptions" module index page.

Full description of the source code
You can learn more about this example on the training courses listed on this page, on which you'll be given a full set of training notes.

Many other training modules are available for download (for limited use) from our download centre under an Open Training Notes License.

Other resources
• Our Solutions centre provides a number of longer technical articles.
• Our Opentalk forum archive provides a question and answer centre.
The Horse's mouth provides a daily tip or thought.
• Further resources are available via the resources centre.
• All of these resources can be searched through through our search engine
• And there's a global index here.

Web site author
This web site is written and maintained by Well House Consultants.

Purpose of this website
This is a sample program, class demonstration or answer from a training course. It's main purpose is to provide an after-course service to customers who have attended our public private or on site courses, but the examples are made generally available under conditions described below.

Conditions of use
Past attendees on our training courses are welcome to use individual examples in the course of their programming, but must check the examples they use to ensure that they are suitable for their job. Remember that some of our examples show you how not to do things - check in your notes. Well House Consultants take no responsibility for the suitability of these example programs to customer's needs.

This program is copyright Well House Consultants Ltd. You are forbidden from using it for running your own training courses without our prior written permission. See our page on courseware provision for more details.

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