Downloaded 29 times
![@etiene_dHackference 2016
Tables
local a = { 1, 3, 5, 7, 9}
local sum = 0
for i=1,#a do
sum = sum + a[i]
end
print(sum) -- 25](https://image.slidesharecdn.com/20161021hackference-161021145114/75/Get-started-with-Lua-Hackference-2016-28-2048.jpg)
![@etiene_dHackference 2016
local a = { 1, 3, 5, 7, 9}
local sum = 0
for i=1,#a do
sum = sum + a[i]
end
print(sum) -- 25
Tables
local a = {}
a[1] = 1
a[2] = 3 -- etc
local sum = 0
for _, x in ipairs(a) do
sum = sum + x
end
print(sum)](https://image.slidesharecdn.com/20161021hackference-161021145114/75/Get-started-with-Lua-Hackference-2016-29-2048.jpg)
![@etiene_dHackference 2016
local a = { 1, 3, 5, 7, 9}
local sum = 0
for i=1,#a do
sum = sum + a[i]
end
print(sum) -- 25
local point = { x = 10, y = 25}
print(point[“x”], point[“y”]) -- 10 25
print(point.x, point.y) -- 10 25
print(point[x], point[y]) -- nil nil (attention!)
Tables](https://image.slidesharecdn.com/20161021hackference-161021145114/75/Get-started-with-Lua-Hackference-2016-30-2048.jpg)
![@etiene_dHackference 2016
local a = { 1, 3, 5, 7, 9}
local sum = 0
for i=1,#a do
sum = sum + a[i]
end
print(sum) -- 25
local point = { x = 10, y = 25}
print(point[“x”], point[“y”]) -- 10 25
print(point.x, point.y) -- 10 25
print(point[x], point[y]) -- nil nil (attention!)
-- sets and multisets
local ips = {[“5.101.112.0”] = true, [“213.35.128.0”] = true}
local conns = {[“5.101.112.0”] = 5, [“213.35.128.0”] = 2}
Tables](https://image.slidesharecdn.com/20161021hackference-161021145114/75/Get-started-with-Lua-Hackference-2016-31-2048.jpg)
![@etiene_dHackference 2016
-- Cipher module
--[[ Based on algorithms/caesar_cipher.lua
by Roland Yonaba ]]
local cipher = {}
local function ascii_base(s)
return s:lower() == s and ('a'):byte() or ('A'):byte()
end
function cipher.caesar( str, key )
return str:gsub('%a', function(s)
local base = ascii_base(s)
return string.char(((s:byte() - base + key) % 26) + base)
end)
end
return cipher
Modules](https://image.slidesharecdn.com/20161021hackference-161021145114/75/Get-started-with-Lua-Hackference-2016-32-2048.jpg)
![@etiene_dHackference 2016
-- Cipher module
--[[ Based on algorithms/caesar_cipher.lua
by Roland Yonaba ]]
local cipher = {}
local function ascii_base(s)
return s:lower() == s and ('a'):byte() or ('A'):byte()
end
function cipher.caesar( str, key )
return str:gsub('%a', function(s)
local base = ascii_base(s)
return string.char(((s:byte() - base + key) % 26) + base)
end)
end
return cipher
Modules](https://image.slidesharecdn.com/20161021hackference-161021145114/75/Get-started-with-Lua-Hackference-2016-33-2048.jpg)
![@etiene_dHackference 2016
-- Cipher module
--[[ Based on algorithms/caesar_cipher.lua
by Roland Yonaba ]]
local cipher = {}
local function ascii_base(s)
return s:lower() == s and ('a'):byte() or ('A'):byte()
end
function cipher.caesar( str, key ) --cipher.caesar = function(str,key)
return str:gsub('%a', function(s) --cipher["caesar"] = function(str,key)
local base = ascii_base(s)
return string.char(((s:byte() - base + key) % 26) + base)
end)
end
return cipher
Modules
public](https://image.slidesharecdn.com/20161021hackference-161021145114/75/Get-started-with-Lua-Hackference-2016-34-2048.jpg)
![@etiene_dHackference 2016
-- Cipher module
--[[ Based on algorithms/caesar_cipher.lua
by Roland Yonaba ]]
local cipher = {}
local function ascii_base(s)
return s:lower() == s and ('a'):byte() or ('A'):byte()
end
function cipher.caesar( str, key )
return str:gsub('%a', function(s)
local base = ascii_base(s)
return string.char(((s:byte() - base + key) % 26) + base)
end)
end
return cipher
Modules
private](https://image.slidesharecdn.com/20161021hackference-161021145114/75/Get-started-with-Lua-Hackference-2016-35-2048.jpg)
![@etiene_dHackference 2016
-- Cipher module
--[[ Based on algorithms/caesar_cipher.lua
by Roland Yonaba ]]
local cipher = {}
local function ascii_base(s)
return s:lower() == s and ('a'):byte() or ('A'):byte()
end
function cipher.caesar( str, key )
return str:gsub('%a', function(s)
local base = ascii_base(s)
return string.char(((s:byte() - base + key) % 26) + base)
end)
end
return cipher
Modules
local c = require “cipher”
print(c.caesar(“test”,3) -- whvw](https://image.slidesharecdn.com/20161021hackference-161021145114/75/Get-started-with-Lua-Hackference-2016-36-2048.jpg)
Uploaded byEtiene Dalcol
Get started with Lua - Hackference 2016
The document introduces Lua, a dynamic, multi-paradigm programming language known for its simplicity and power, highlighting its features such as garbage collection, first-class functions, and support for object-oriented programming. It also discusses the usage of tables as a primary data structure, various idioms, and showcases code samples for embedding Lua in applications. Additionally, the document touches on Lua's metatables and encapsulation of complex numbers and objects, emphasizing its versatility and usability in different programming paradigms.
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Get started with Lua - Hackference 2016
- 1. Get started with EtieneDalcol @etiene_d
- 2.
- 3. @etiene_dHackference 2016 A LuaMVC web framework sailorproject.org
- 4.
- 5.
- 6. @etiene_dHackference 2016 What’s Lua WhyLua Key Concepts
- 7.
- 8. @etiene_dHackference 2016 • Dynamicduck-typed language • Multi-paradigm • procedural, OO, functional • Garbage collection • Coroutines • First-class functions • Lexical scoping • Proper tail calls • MIT License What is Lua?
- 9.
- 10. @etiene_dHackference 2016 Why Lua? Size (docsincluded) First-class functions + Lexical scoping + Metatables Native C API 276 Kb Object Orientation Ada, Fortran, Java, Smalltalk, C#, Perl, Ruby etc. +
- 11.
- 12.
- 13.
- 14. Hackference 2016 @etiene_d "SinceLua itself is so simple, it tends to encourage you to solve problems simply." Ragnar Svensson - Lead Developer at King (Lua Workshop Oct 15 2015)
- 15.
- 16.
- 17. @etiene_dHackference 2016 My Reasons •It looks cool (I heard you could make games with it) Better
- 18. @etiene_dHackference 2016 Better Reasons •It looks cool (I heard you could make games with it) • It’s made in my home country (In my university to be more precise)
- 19. @etiene_dHackference 2016 • Itlooks cool (I heard you could make games with it) • It’s made in my home country (In my university to be more precise) • It’s easy to learn Better Reasons
- 20. @etiene_dHackference 2016 • Theindex starts at 1 • There’s no continue • The non-equality operator is ~= • null is nil • Comments are - - • Only nil and false are equivalent to false • Functions can genuinely return multiple values • Variables are global by default • Pattern matching is not regular expression • The concatenation operator is .. What’s different
- 21. @etiene_dHackference 2016 Quick idioms •a, b = b, a • There’s no ternary operator but you can return x==1 and “yes” or “no” • The access to local variables is faster than to global local match = string.match
- 22. @etiene_dHackference 2016 Using Lua:three approaches Embedded Scripting General-purpose
- 23. @etiene_dHackference 2016 Getting Lua •lua.org > download • OS package manager • apt-get install lua • brew install lua LuaRocks • luarocks.org > install • OS package manager • apt-get install luarocks
- 24.
- 25. @etiene_dHackference 2016 • Theonly way to structure data • Array, dictionary, object, list, queue, module… • Any value can be a key, except nil and nan • Behind the scenes: array or hash table • Passed as reference • The length operator: # • pairs(t) x ipairs(t) Tables Tables Tables
- 26. @etiene_dHackference 2016 Tables Header key value “x”9.2 nil value 100 200 300 nil
- 27. @etiene_dHackference 2016 • Theonly way to structure data • Array, dictionary, object, list, queue, module… • Any value can be a key, except nil • Behind the scenes: array or hash table • Passed as reference • The length operator: # • pairs(t) x ipairs(t) Tables
- 28. @etiene_dHackference 2016 Tables local a= { 1, 3, 5, 7, 9} local sum = 0 for i=1,#a do sum = sum + a[i] end print(sum) -- 25
- 29. @etiene_dHackference 2016 local a= { 1, 3, 5, 7, 9} local sum = 0 for i=1,#a do sum = sum + a[i] end print(sum) -- 25 Tables local a = {} a[1] = 1 a[2] = 3 -- etc local sum = 0 for _, x in ipairs(a) do sum = sum + x end print(sum)
- 30. @etiene_dHackference 2016 local a= { 1, 3, 5, 7, 9} local sum = 0 for i=1,#a do sum = sum + a[i] end print(sum) -- 25 local point = { x = 10, y = 25} print(point[“x”], point[“y”]) -- 10 25 print(point.x, point.y) -- 10 25 print(point[x], point[y]) -- nil nil (attention!) Tables
- 31. @etiene_dHackference 2016 local a= { 1, 3, 5, 7, 9} local sum = 0 for i=1,#a do sum = sum + a[i] end print(sum) -- 25 local point = { x = 10, y = 25} print(point[“x”], point[“y”]) -- 10 25 print(point.x, point.y) -- 10 25 print(point[x], point[y]) -- nil nil (attention!) -- sets and multisets local ips = {[“5.101.112.0”] = true, [“213.35.128.0”] = true} local conns = {[“5.101.112.0”] = 5, [“213.35.128.0”] = 2} Tables
- 32. @etiene_dHackference 2016 -- Ciphermodule --[[ Based on algorithms/caesar_cipher.lua by Roland Yonaba ]] local cipher = {} local function ascii_base(s) return s:lower() == s and ('a'):byte() or ('A'):byte() end function cipher.caesar( str, key ) return str:gsub('%a', function(s) local base = ascii_base(s) return string.char(((s:byte() - base + key) % 26) + base) end) end return cipher Modules
- 33. @etiene_dHackference 2016 -- Ciphermodule --[[ Based on algorithms/caesar_cipher.lua by Roland Yonaba ]] local cipher = {} local function ascii_base(s) return s:lower() == s and ('a'):byte() or ('A'):byte() end function cipher.caesar( str, key ) return str:gsub('%a', function(s) local base = ascii_base(s) return string.char(((s:byte() - base + key) % 26) + base) end) end return cipher Modules
- 34. @etiene_dHackference 2016 -- Ciphermodule --[[ Based on algorithms/caesar_cipher.lua by Roland Yonaba ]] local cipher = {} local function ascii_base(s) return s:lower() == s and ('a'):byte() or ('A'):byte() end function cipher.caesar( str, key ) --cipher.caesar = function(str,key) return str:gsub('%a', function(s) --cipher["caesar"] = function(str,key) local base = ascii_base(s) return string.char(((s:byte() - base + key) % 26) + base) end) end return cipher Modules public
- 35. @etiene_dHackference 2016 -- Ciphermodule --[[ Based on algorithms/caesar_cipher.lua by Roland Yonaba ]] local cipher = {} local function ascii_base(s) return s:lower() == s and ('a'):byte() or ('A'):byte() end function cipher.caesar( str, key ) return str:gsub('%a', function(s) local base = ascii_base(s) return string.char(((s:byte() - base + key) % 26) + base) end) end return cipher Modules private
- 36. @etiene_dHackference 2016 -- Ciphermodule --[[ Based on algorithms/caesar_cipher.lua by Roland Yonaba ]] local cipher = {} local function ascii_base(s) return s:lower() == s and ('a'):byte() or ('A'):byte() end function cipher.caesar( str, key ) return str:gsub('%a', function(s) local base = ascii_base(s) return string.char(((s:byte() - base + key) % 26) + base) end) end return cipher Modules local c = require “cipher” print(c.caesar(“test”,3) -- whvw
- 37. @etiene_dHackference 2016 • Overloadoperators • Override built-in functions such as tostring • Treat missing fields or intercept new field creation • Call table as a function • Metamethods: __add, __sub, __mul, __div, __mod, __pow, __unm, __concat, __len, __eq, __lt, __le, __index, __newindex, __call, __tostring, __ipairs, __pairs, __gc Metatables
- 38. @etiene_dHackference 2016 local mt= {} local function new(r, i) return setmetatable({ real = r or 0, im = i or 0}, mt) end local function is_complex(v) return getmetatable(v) == mt end local function add(c1, c2) if not is_complex(c1) then return new(c2.real + c1, c2.im) elseif not is_complex(c2) then return new(c1.real + c2, c1.im) end return new(c1.real + c2.real, c1.im + c2.im) end local function tos(c) return tostring(c.real) .. "+".. tostring(c.im) .. "i" end mt.__add = add mt.__tostring = tos Complex numbers
- 39. @etiene_dHackference 2016 local mt= {} local function new(r, i) return setmetatable({ real = r or 0, im = i or 0}, mt) end local function is_complex(v) return getmetatable(v) == mt end local function add(c1, c2) if not is_complex(c1) then return new(c2.real + c1, c2.im) elseif not is_complex(c2) then return new(c1.real + c2, c1.im) end return new(c1.real + c2.real, c1.im + c2.im) end local function tos(c) return tostring(c.real) .. "+".. tostring(c.im) .. "i" end mt.__add = add mt.__tostring = tos Complex numbers
- 40. @etiene_dHackference 2016 local mt= {} local function new(r, i) return setmetatable({ real = r or 0, im = i or 0}, mt) end local function is_complex(v) return getmetatable(v) == mt end local function add(c1, c2) if not is_complex(c1) then return new(c2.real + c1, c2.im) elseif not is_complex(c2) then return new(c1.real + c2, c1.im) end return new(c1.real + c2.real, c1.im + c2.im) end local function tos(c) return tostring(c.real) .. "+".. tostring(c.im) .. "i" end mt.__add = add mt.__tostring = tos Complex numbers
- 41. @etiene_dHackference 2016 local mt= {} local function new(r, i) return setmetatable({ real = r or 0, im = i or 0}, mt) end local function is_complex(v) return getmetatable(v) == mt end local function add(c1, c2) if not is_complex(c1) then return new(c2.real + c1, c2.im) elseif not is_complex(c2) then return new(c1.real + c2, c1.im) end return new(c1.real + c2.real, c1.im + c2.im) end local function tos(c) return tostring(c.real) .. "+".. tostring(c.im) .. "i" end mt.__add = add mt.__tostring = tos Complex numbers
- 42. @etiene_dHackference 2016 local mt= {} local function new(r, i) return setmetatable({ real = r or 0, im = i or 0}, mt) end local function is_complex(v) return getmetatable(v) == mt end local function add(c1, c2) if not is_complex(c1) then return new(c2.real + c1, c2.im) elseif not is_complex(c2) then return new(c1.real + c2, c1.im) end return new(c1.real + c2.real, c1.im + c2.im) end local function tos(c) return tostring(c.real) .. "+".. tostring(c.im) .. "i" end mt.__add = add mt.__tostring = tos Complex numbers
- 43. @etiene_dHackference 2016 local mt= {} local function new(r, i) return setmetatable({ real = r or 0, im = i or 0}, mt) end local function is_complex(v) return getmetatable(v) == mt end local function add(c1, c2) if not is_complex(c1) then return new(c2.real + c1, c2.im) elseif not is_complex(c2) then return new(c1.real + c2, c1.im) end return new(c1.real + c2.real, c1.im + c2.im) end local function tos(c) return tostring(c.real) .. "+".. tostring(c.im) .. "i" end mt.__add = add mt.__tostring = tos >local c1 = new(2,3) >print( c1 + 5 ) 7+3i Complex numbers
- 44. @etiene_dHackference 2016 local square= { x = 10, y = 20, side = 25 } function square.move(obj, dx, dy) obj.x = obj.x + dx obj.y = obj.y + dy end function square:area() return self.side ^ 2 end print(square:area()) -- 625 Objects
- 45. @etiene_dHackference 2016 local square= { x = 10, y = 20, side = 25 } function square.move(obj, dx, dy) obj.x = obj.x + dx obj.y = obj.y + dy end function square:area() return self.side ^ 2 end print(square:area()) -- 625 Objects
- 46. @etiene_dHackference 2016 local square= { x = 10, y = 20, side = 25 } function square.move(obj, dx, dy) obj.x = obj.x + dx obj.y = obj.y + dy end function square:area() return self.side ^ 2 end print(square:area()) -- 625 Objects
- 47. @etiene_dHackference 2016 local square= { x = 10, y = 20, side = 25 } function square.move(obj, dx, dy) obj.x = obj.x + dx obj.y = obj.y + dy end function square:area() return self.side ^ 2 end print(square:area()) -- 625 Objects
- 48. @etiene_dHackference 2016 local square= { x = 10, y = 20, side = 25 } function square.move(obj, dx, dy) obj.x = obj.x + dx obj.y = obj.y + dy end function square:area() return self.side ^ 2 end print(square:area()) -- 625 local square2 = (x = 30, y = 5, side = 10} print(square.area(square2)) -- 100 Objects
- 49. @etiene_dHackference 2016 local Square= {} function Square:new(x, y, side) local o = { x = x, y = y, side = side} setmetatable(o, self) self.__index = self return o end function Square:move(dx, dy) self.x = self.x + dx self.y = self.y + dy end function Square:area() return self.side ^ 2 end return Square Object Orientation
- 50. @etiene_dHackference 2016 local Square= {} function Square:new(x, y, side) local o = { x = x, y = y, side = side} setmetatable(o, self) self.__index = self return o end function Square:move(dx, dy) self.x = self.x + dx self.y = self.y + dy end function Square:area() return self.side ^ 2 end return Square Object Orientation
- 51. @etiene_dHackference 2016 local Square= {} function Square:new(x, y, side) local o = { x = x, y = y, side = side} setmetatable(o, self) self.__index = self return o end function Square:move(dx, dy) self.x = self.x + dx self.y = self.y + dy end function Square:area() return self.side ^ 2 end return Square Object Orientation
- 52. @etiene_dHackference 2016 local Square= {} function Square:new(x, y, side) local o = { x = x, y = y, side = side} setmetatable(o, self) self.__index = self return o end function Square:move(dx, dy) self.x = self.x + dx self.y = self.y + dy end function Square:area() return self.side ^ 2 end return Square Object Orientation
- 53. @etiene_dHackference 2016 local Square= {} function Square:new(x, y, side) local o = { x = x, y = y, side = side} setmetatable(o, self) self.__index = self return o end function Square:move(dx, dy) self.x = self.x + dx self.y = self.y + dy end function Square:area() return self.side ^ 2 end return Square local Square = require “square” local s1 = Square:new(10,20,25) local s2 = Square:new(30,5,10) print(s1:area()) -- 625 print(s2:area()) -- 100 Object Orientation
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- 56. @etiene_dHackference 2016 • Hardware •eLua: http://www.eluaproject.net/ • nodemcu: http://nodemcu.com • Scientific Computing and Machine Learning • SciLua http://www.scilua.org/ • Torch: http://torch.ch • GSL Shell: http://www.nongnu.org/gsl-shell/ Cool tools in Lua
- 57. @etiene_dHackference 2016 • Gamedevelopment • Love2D: https://love2d.org/ • Defold: http://www.defold.com/ • Cocos2d: http://www.cocos2d-x.org/ • Corona: https://coronalabs.com • Web development • (Nginx) OpenResty http://openresty.org • Luvit: https://luvit.io/ • Lapis: http://leafo.net/lapis/ • Sailor: http://sailorproject.org/ • Starlight: http://starlight.paulcuth.me.uk/ Cool tools in Lua
- 58. @etiene_dHackference 2016 • IDE •ZeroBrane Studio: http://studio.zerobrane.com/ • Testing • Busted: http://olivinelabs.com/busted/ • Package management • LuaRocks http://luarocks.org • Misc • Moonscript: http://moonscript.org/ • Awesome Lua: https://github.com/LewisJEllis/awesome-lua Cool tools in Lua
- 59. @etiene_dHackference 2016 • Community •Lua mail list: http://www.lua.org/lua-l.html • #LuaLang on Twitter • Lua community blog: http://lua.space • Lua’s subreddit: http://reddit.com/r/lua • Lua’s IRC channel: irc.freenode.net #lua • Books • Programming in Lua: http://www.lua.org/pil/ • Lua Programming Gems: http://www.lua.org/gems/ • Misc • CodeCombat: https://codecombat.com Resources
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