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Lua module U111
Trapping and handling errors.
Exercises, examples and other material relating to training module U111. This topic is presented on public courses Learning to program in Lua, Lua Programming, Lua Programming




Articles and tips on this subjectupdated
2360Error Handling in Lua with assert and pcall
When a function fails in lua, you'll often find that it return a nil value that you can check, or it returns two values, the second of which is an error status / message that tells you what went wrong. Here's an example: value = tonumber(stuff) if value == nil then    print ("Nah!") else    print ...
2010-06-19
 
2706Error trapping in Lua - no exceptions.
Lua's a small language - it's about a twentieth of the size of most of the others I teach - so there isn't the space for the nicities of things like expection handling. But it does very nicely, thank you! Functions return nil (false) values if they fail, and true values (even 0 is true in Lua, which ...
2010-04-03
 
2455Lua examples - coroutines, error handling, objects, etc
I have presented a bespoke Lua course over the last three days ... and it has lead me to some interesting new examples which I'm sharing here. Object Orientation is more a way of thinking and coding than a language feature in Lua - when you set up a piece of data / structure / object, you do so in a ...
2009-10-17
 
Examples from our training material
errc   Error handling on file open
gp0   'Control' for error trapping - failing example
gp1   trapping an error via pcall
gp2   Assert - test a condition and exit with your error if it fails
protectedcall   pcall to trap errors in a lua function call
splot   trapping Lua errors - nil and error
splut   trapping Lua errors - assert
tbp   Stack Traceback
wonky   error checking through pcall
Background information
Some modules are available for download as a sample of our material or under an Open Training Notes License for free download from http://www.training-notes.co.uk.
Topics covered in this module
Logic, syntax, runtime.
Assert and Error functions.
Error Containment Functions such as pcall
debug.stacktrace
Complete learning
If you are looking for a complete course and not just a information on a single subject, visit our Listing and schedule page.

Well House Consultants specialise in training courses in Python, Perl, PHP, and MySQL. We run Private Courses throughout the UK (and beyond for longer courses), and Public Courses at our training centre in Melksham, Wiltshire, England. It's surprisingly cost effective to come on our public courses - even if you live in a different country or continent to us.

We have a technical library of over 700 books on the subjects on which we teach. These books are available for reference at our training centre. Also available is the Opentalk Forum for discussion of technical questions.


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