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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 Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own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))
Line, block and nested comments - Lua compared to other languages

You can comment your Lua program in two ways.

a) using comments that start -- , in which case they run to the end of the line - so that's a line comment

b) starting --[[ , in which case they run through to the next ]] which may be in the same line, or a number of lines later - so that's a block comment

Line and block comments are common in many other languages too
• in PHP, for example, a line comment starts with a # or //, and a block comment runs from /* to */.
• in C++ and in Java, line comments start with //, and block comments run from /* to */.
• ANSI C only supports block comments from /* to */, though some extended compilers accept line comments from //.
&bull, In Tcl, Perl and Python you have just line comment support from # to the end of the line
and in all the languages we teach, blank lines will be ignored too so are in effect a separating comment

One of the things I regret about block comments in most langauges is that they cannot be nested. In other words, you can't write a comment with a comment. "Does this matter?" you ask. Yes, it does to me ... I want to be able to comment out a whole block of code that's already got comments within it, and that's a problem where the end of the inner comment also forces the end of the outer comment. Lua (uniquely in the languages we teach) provides a solution in that block comments can start with extra = signs between the [ and [, and then the terminating sequeence need to have the same number of == signs ... so

  print ("This will be printed first")
  --[===[ Comment out a whole big block!
  --[[ This is a multiline comment telling you about
  the work this code is doing ]]
  print ("This will not be printed in the middle")
  --[[ This is another multiline comment telling you about
  the work this code is doing ]]
  end of big block comment ]===]
  print ("This will be printed last")

will just print out two lines, with the one in the middle being skipped.

Examples, in context - see [here].
(written 2014-05-04, updated 2014-05-06)

Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
U101 - Introduction to Lua.
  [1111] Training in Lua - (2007-03-16)
  [1695] Lua Course - here is the index - (2008-07-03)
  [1699] If you are learning Lua, here are some more examples - (2008-07-06)
  [1737] Rules, suggestions, considerations for Lua variable names - (2008-08-05)
  [1842] Lua Course, and the Wiltshire Countryside too - (2008-10-16)
  [2310] Learning to write high quality code in Lua - (2009-07-30)
  [3724] Learning to Program in Lua - public / open training course / class - (2012-05-09)
  [4324] Learning to program - variables and constants - (2014-11-22)

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Lazy operators in Lua - what they mean, and examples
Line, block and nested comments - Lua compared to other languages
Embedding Lua to perform tailored code at an interval
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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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