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 Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own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)) |
Tables with values and code in Lua - looks like an object?
In Lua, we can use variables to hold both data and code, and we can use tables to hold groups of values (numbers and strings) and code assiciated with those variables too. A new example - [here] on our web site - shows how I can define such a table:
south = {cars=3,seats=78,time="06:38",destiny="Southampton"}
add a function (code) to it:
function capacity(of)
local peeps = math.floor(of.cars * of.seats * 1.4)
return peeps
end
south.getCapacity = capacity
I can then run that code on the data using
takes = south.getCapacity(south)
or
takes = south:getCapacity()
The real gains start to come when I produce a whole table of servives, perhaps of different types (trains and buses) with differing code to work out the capacity. The need for "if" and "else" type coding in the getCapacity loop melts away:
for _,service in ipairs(services) do
print("Can carry " .. service:getCapacity() .. " to " .. service.destiny)
end
From our Learning to program in Lua course, running this week, again next week, and available every 2 months next year. Check [here] for the next dates. (written 2015-11-05)
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) [4273] Dot or Colon separator between table name and member in Lua - what is the difference? - (2014-05-06) [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)
Some other Articles
If it's Tuesday it must be Belgium?Learning not just what a program does, but how to design it in the first place.repeat until in Lua - a one or more rather than a zero or more loopTables with values and code in Lua - looks like an object?Lua - using modules to add your own utilitiesA warm welcome awaits you at Well House Manor, MelkshamLua - changes to how integers and floats are handled - 5.2 to 5.3Moderation - and the tendency to over-moderateJapanese and Malaysian food in Melksham
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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.
Link to Ezine home page (for reading).
Link to Blogging home page (to add comments).
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