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For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))
Exceptions in Ruby - throwing, catching and using

It's far better to use exceptions to trap run time irregularities than to try to forecast all possible errors, as exceptions form a sort of safety net. From today's Ruby Course, [here] is an example where the user is prompted to enter an integer, and I deliberately use the Integer function rather than to_i to extract that number so that I can catch incorrect entries through an exception (Integer throws exceptions, but to_i just returns a 0).

A further example - [here] - shows how exceptions can be caught in methods or thorn up to parents, and how methods can even raise their own exceptions. If you're writing methods, it's sensible to throw exceptions up as it forces the person using you code to take into account situations where no value is to be returned.


(written 2016-05-17)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
R111 - Ruby - Exceptions.
  [1875] What are exceptions - Python based answer - (2008-11-08)
  [2615] String to number conversion with error trapping in Ruby - (2010-02-01)
  [2620] Direct access to object variable (attributes) in Ruby - (2010-02-02)
  [2621] Ruby collections and strings - some new examples - (2010-02-03)
  [2622] Handling unusual and error conditions - exceptions - (2010-02-03)
  [3177] Insurance against any errors - Volcanoes and Python - (2011-02-19)
  [3260] Ruby - a training example that puts many language elements together to demonstrate the whole - (2011-04-23)
  [3433] Exceptions - a fail-safe way of trapping things that may go wrong - (2011-09-11)
  [3435] Sorta sorting a hash, and what if an exception is NOT thrown - Ruby - (2011-09-12)
  [4008] Reading and checking user inputs - first lessons - Ruby - (2013-02-17)


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Reading in XML in Ruby with xmlsimple
Expect with Ruby - a training example to get you started
Swindon, Chippenham and Melksham - day trips by train to Weymouth start for 2016
Running shell (operating system) commands from within Ruby
Exceptions in Ruby - throwing, catching and using
Alternating valuses / flip-flop / toggle - example in Ruby
Separating detailed data code from the main application - Ruby example
Annual review of Melksham Matters for Chamber of Commerce AGM
Ruby training, half a world away
The end, or the start?
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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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