Lua tables - they are everything

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 Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own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

In PHP, it sometimes feels like the answer to every question is "there's a function to do that" and in Lua, it seems the answer is always "it's a table" or "use a table"!

I'm running a Lua course this week, and I have just posted up an example in which I set up a table and showed some of the flexibilities - full example [here].

A table is Lua's collection variable - a variable that holds other variables. It may be indexed by numbers (and that's an ordered table, which can be sorted), or by member name (an unordered table, using a hashing technique, so unsortable directly), or even as a mixture, as I've done in the example just quoted.

Variables themselves are very flexible - Lua is a tiny language, and so variables also contain just about everything in order to cut down on the footprint ... that means that a variable can contain a number, a string of text, or another table or a named block of code (yes, that's a function) - all are in the same "namespace" and all are handled by the same base language code.

Do you need to see under Lua'a cover like this in order to use it? Well - it certainly helps to understand just a smidgin of what's going on inside, as that allows you to make the very best use of the language, and allows you to quickly find and rectify coding issues that are associated with this sharing of namespace.
(written 2010-03-30, updated 2010-03-31)

Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles

U105 - Lua - Tables and the table library.
  [1697] Sorting in lua - specifying your own sort routine - (2008-07-05)
  [1742] Lua - Table elements v table as a whole - (2008-08-07)
  [2346] The indexed and hashed parts of a Lua table - (2009-08-10)
  [2499] ourdog is Greyhound, Staffie and Ginger Cake - (2009-11-09)
  [2703] Lua Metatables - (2010-04-02)
  [3694] Special __ methods you can use in Lua metatables - (2012-04-12)
  [3725] Lua Tables - (2012-05-10)
  [4248] Metatables, Metamethods, classes and objects in Lua - (2014-03-18)
  [4273] Dot or Colon separator between table name and member in Lua - what is the difference? - (2014-05-06)
  [4571] Lua - using modules to add your own utilities - (2015-11-04)

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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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