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Dot, dot, dot in Lua - variable length parameter lists

Each delegate has his own machineLua functions can take any number of parameters - the ... (dot,dot,dot) table given as a parameter 'soaking up' all remaining parameters into the indexed section of the table, rather this "*" in front of a parameter in PHP. (In Perl, the whole list appears in @_)

function join (sep,...)
togo = {...}


There are two styles to calling Lua functions - passing in a comma separated list of parameters in round brackets, or combining them into a table in curly braces:

-- Many parameter variety
str1 = join(" ","This","is","a","Program")
-- Two parameter variety
str2 = join(" ",{"This","is","another","Program"})


And the code within the function can tell the styles apart and adapt itself as appropriate by checking the number and/or type of parameters:

if type(togo[1]) == "table" then

See source code of full example


Illustration - delegates on a private Lua course. We run public Lua training courses at our centre in Melksham, Wiltshire, England and private course onsite worldwide.



(written 2009-08-11, updated 2010-06-19)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
U106 - Lua - Functions.
  [3695] Functions are first class variables in Lua and Python - (2012-04-13)
  [2949] Lua - variable function arguments and select - (2010-09-08)
  [2723] Returning multiple values from a function - Lua - (2010-04-15)
  [2455] Lua examples - coroutines, error handling, objects, etc - (2009-10-15)
  [2356] Passing multiple results back from a function - Lua, Python, etc - (2009-08-13)
  [2312] What are closures in Lua? - (2009-07-31)
  [1847] Lua - IAQ (Infrequently Answered Questions) - (2008-10-18)
  [1744] Lua examples, Lua Courses - (2008-08-08)
  [1743] First class functions in Lua lead to powerful OO facilities - (2008-08-07)
  [1699] If you are learning Lua, here are some more examples - (2008-07-06)
  [1697] Sorting in lua - specifying your own sort routine - (2008-07-05)
  [1685] Short circuit evaluation (lazy operator) in Lua - (2008-06-22)


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Ten years in Melksham - looking forward to ten more.
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Finding literals rather than patterns in Lua
Dot, dot, dot in Lua - variable length parameter lists
The indexed and hashed parts of a Lua table
Automatically initialising Lua variables the first time
Reading a data file and sensing EOF in Lua
World Flags in your PHP pages
Training Classes in other tongues
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