Dot or Colon separator between table name and member in Lua

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 Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own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

Dot or Colon separator between table name and member in Lua - what is the difference?

When do I use a dot and when do I use a colon in referencing a table member in Lua? It's a good question and one that we answer (and demonstrate to help make clear) on our Lua Programming Course.

Dot refers to a table member. So if I write
  source.read()
I am saying "run the read function in the table called source". Perhaps that's all I want to do, but it's more likely that the read funiction needs to refer to other things in that same table, so it needs to be passed in as a parameter - so
  source.read(source)
and that works perfectly well. But it looks clumsy, and it means the table name has to be entered twice into the code. So that can be rewritten as
  source:read()

Coded example [here]. Lua course run by us here.
(written 2014-05-06)

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

U107 - Object Orientation - the Lua way
  [1692] Towards Object Oriented Programming in Lua - (2008-06-30)
  [1699] If you are learning Lua, here are some more examples - (2008-07-06)
  [1743] First class functions in Lua lead to powerful OO facilities - (2008-08-07)
  [1819] Calling base class constructors - (2008-10-03)
  [2318] For Lua Programmers AND for Town Planners - (2009-08-02)
  [2359] A fresh example - objects the Lua way - (2009-08-13)
  [2455] Lua examples - coroutines, error handling, objects, etc - (2009-10-15)
  [2701] Is Lua an Object Oriented language? - (2010-04-01)
  [2703] Lua Metatables - (2010-04-02)
  [2710] __index and __newindex in Lua - metatable methods - (2010-04-05)
  [3142] Private and Public - and things between - (2011-01-22)
  [3396] Tables as Objects in Lua - a gentle introduction to data driven programming - (2011-08-17)
  [3524] Metaclasses (Python) and Metatables (Lua) - (2011-11-17)
  [3683] Weak references in Lua - what are they, and why use them? - (2012-04-04)
  [3694] Special __ methods you can use in Lua metatables - (2012-04-12)
  [3727] Using Lua tables as objects - (2012-05-11)
  [3730] What is a metatable? How do I set one up? How do I use them? Lua - (2012-05-12)
  [4117] Is Lua an Object Oriented language? - (2013-06-15)
  [4248] Metatables, Metamethods, classes and objects in Lua - (2014-03-18)
  [4572] Tables with values and code in Lua - looks like an object? - (2015-11-05)
  [4573] Classic style OO code - in Lua - (2015-11-05)
  [4753] Lua, Tcl, Python, C and C++ courses - at our Melksham HQ or on your site - forward from July 2017 - (2017-07-02)

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)
  [2699] Lua tables - they are everything - (2010-03-30)
  [3725] Lua Tables - (2012-05-10)
  [4571] Lua - using modules to add your own utilities - (2015-11-04)

Back to
Lazy operators in Lua - what they mean, and examples

Previous and next
or
Horse's mouth home

Forward to
String formatting in Lua - string.format as a wrapper for sprintf

Some other Articles

Sending a message to the server and changing text on a page when a button is pressed
Swindon to Weymouth - by train, the traditional way - 2014
Eurpoean Elections, and other elections ahead. Some thoughts on campaigns and policies
String formatting in Lua - string.format as a wrapper for sprintf
Dot or Colon separator between table name and member in Lua - what is the difference?
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
Survey - Journeys
Metrics - historic and current TransWilts train use

4759 posts, page by page

Link to page ... 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96 at 50 posts per page

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.

Link to Ezine home page (for reading).
Link to Blogging home page (to add comments).

You can Add a comment or ranking to this page

Like this? ??