-- Delphi like with statement
function with(obj)
local store = { {}, obj, _G[''__with''] }
local vars = store[1]
for k,v in obj do
vars[k] = _G[k]
_G[k] = obj[k]
end
_G[''__with''] = store
end
function endwith()
local storage = _G[''__with'']
if not storage then return end
local vars = storage[1]
local obj = storage[2]
for k,v in vars do
obj[k] = _G[k]
_G[k] = vars[k]
end
_G[''__with''] = storage[3]
end
--------------------------------------------------
-- test code below
--------------------------------------------------
a = { x=100,
printme = function(...) for k,v in ipairs(arg) do print(''arg''..k,v) end end
}
for k,v in a do print( "a."..k, v) end
x = 50
with(a)
x= 100
printme("Hello",x)
x= 150
printme("Hello",x)
endwith()
print("x=",x)
for k,v in a do print( "a."..k, v) end
-- following should fail, printme was defined in a
ok, msg = pcall(printme, "Hello")
if ok then print(''Function printme OK.'' ) else
print("Function printme failed:"..msg ) end
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with for lua
Author
Lua is so powerful....I was filling in a table/object in lua and I wanted a with statement like Delphi has, so 20 lines of lua later I had one!!
Outside of Lisp/Scheme Lua is the only language that never seems to leave me wanting.....and lua is a LOT more readable to come back to.
It gets even easier than that, through the use of function environments. See the manual for details, in particular the getfenv and setfenv functions.
"Sneftel is correct, if rather vulgar." --Flarelocke
"Sneftel is correct, if rather vulgar." --Flarelocke
We should turn this into a "Lua scraps" thread. Here are the homebrewed functions I use to serialize my level data for my sidescroller.
I just open a file and write out the string returned from serialize, which I just pass the entire level table to. Then that file can be loaded anytime and returns the exact same table. Note: it doesn''t work with threads or functions, and for userdata, the user has to define a toString method.
I just open a file and write out the string returned from serialize, which I just pass the entire level table to. Then that file can be loaded anytime and returns the exact same table. Note: it doesn''t work with threads or functions, and for userdata, the user has to define a toString method.
indent = 3function serialize(t) indentation = 0 local str = "local t = " .. textize(t,3) .. " ; return t; " return str endfunction textize(t,indentation) local str = "{ \n" local tempk,tempv local allnumbers=true for tempk,tempv in t do if type(tempk) ~= ''number'' then allnumbers=false end end str = str .. string.rep('' '',indentation) for k,v in t do if allnumbers == false then str = str .. string.rep('' '',indentation) end if type(k) == ''number'' then if allnumbers == false then str = str .. ''['' .. k .. ''] = '' end elseif type(k) == ''string'' then str = str .. ''["'' .. k .. ''"] = '' else error(''unknown key type in serialize'') end local a = type(v) if a == ''number'' then str = str .. v elseif a == ''string'' then str = str .. ''"'' .. v .. ''"'' elseif a == ''boolean'' then if v then str = str .. ''true'' else str = str .. ''false'' end elseif a == ''thread'' then error(''cannot use threads in serialize'') elseif a == ''userdata'' then if v.toString == nil then error(''to serialize a userdata you must define toString'') end str = str .. v:toString() elseif a == ''table'' then str = str .. textize(v,indentation + indent) end str = str .. '','' if allnumbers == false then str = str .. ''\n'' end end str = str .. ''\n'' .. string.rep('' '',indentation - indent) .. ''}'' return strendquote: Original post by ktw6675
I just open a file and write out the string returned from serialize, which I just pass the entire level table to. Then that file can be loaded anytime and returns the exact same table. Note: it doesn't work with threads or functions, and for userdata, the user has to define a toString method.
Not to toot my own horn, but you may want to check out Pluto; support for saving arbitrarily complex and referential Lua structures, including functions, threads, and userdata. </avertisement>
(Edit: fixed misformatted link)
"Sneftel is correct, if rather vulgar." --Flarelocke
[edited by - sneftel on June 9, 2004 3:23:43 AM]
Um, Sneftel, ads work a lot better with information on how to get to the product. 
(His announcement thread was here.)
(His announcement thread was here.)
Wow...I''m impressed. Pluto looks pretty cool if I may say so myself. In addition to making saving/loading absolutely trivial (the entire "state" of the engine is entirely in Lua...I''m just itching to dump _G to file and load it back up and see things magically come back), this might allow me to do some interesting things with AI persistence and learning. Thanks for the link.
quote: Original post by ktw6675It''s tricky right now, since you''d need to fill the "permanents table" with every C function exported to Lua (including standard library functions). I''m working on that aspect right now; give it a few days.
I''m just itching to dump _G to file and load it back up and see things magically come back
"Sneftel is correct, if rather vulgar." --Flarelocke
This topic is closed to new replies.
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