I have 2 different Lua files, main.lua and game_model.lua. I'm trying to save some details in a JSON file (I googled that using a JSON file would be the best way to save a user's settings and score), but I'm getting the following error:
Error: File: main.lua
Line: 11
Attempt to index local 'game' (a boolean value)
Why is am I getting this error and how can fix it?
Here is the code in my main.lua:
--Main.lua
display.setStatusBar( display.HiddenStatusBar )
local composer = require( "composer" )
local game = require("data.game_model")
myGameSettings = {}
myGameSettings.highScore = 1000
myGameSettings.soundOn = true
myGameSettings.musicOff = true
myGameSettings.playerName = "Andrian Gungon"
game.saveTable(myGameSettings, "mygamesettings.json")
composer.gotoScene("scripts.menu")
game_model.lua (in the data subdirectory) contains this code:
--game_model.lua (located at data/game_model.lua)
local json = require("json")
function saveTable(t, filename)
local path = system.pathForFile( filename, system.DocumentsDirectory)
local file = io.open(path, "w")
if (file) then
local contents = json.encode(t)
file:write( contents )
io.close( file )
return true
else
print( "Error!" )
return false
end
end
function loadTable(filename)
local path = system.pathForFile( filename, system.DocumentsDirectory)
local contents = ""
local myTable = {}
local file = io.open( path, "r" )
if (file) then
local contents = file:read( "*a" )
myTable = json.decode(contents);
io.close( file )
return myTable
end
return nil
end
It means that the module data.game_model did not return anything when it was loaded.
In this case, require returns true.
To fix the problem identified in lhf's answer, you can put your table saving and loading functions in a table that is returned by data.game_model, like this:
-- Filename: data/game_model.lua
local model = {}
local json = require("json")
function model.saveTable( t, filename )
-- code for saving
end
function model.loadTable( filename )
-- code for loading
end
return model
Note also that a common mistake would be to declare the functions as model:saveTable( t, fn ) instead of model.saveTable( t, fn ). Remember, the former is syntactic sugar for model.saveTable( model, t, fn ).
Now the variable game in local game = require( "data.game_model" ) should be initialized to a table containing your functions. You can easily check this:
local game = require("data.game_model")
print( type( game ) )
for k,v in pairs(game) do
print(k,v)
end
Produces output like:
table
loadTable function: 0x7f87925afa50
saveTable function: 0x7f8794d73cf0
Use code below to save/load. All code comes from github/robmiracle.
local M = {}
local json = require("json")
local _defaultLocation = system.DocumentsDirectory
local _realDefaultLocation = _defaultLocation
local _validLocations = {
[system.DocumentsDirectory] = true,
[system.CachesDirectory] = true,
[system.TemporaryDirectory] = true
}
function M.saveTable(t, filename, location)
if location and (not _validLocations[location]) then
error("Attempted to save a table to an invalid location", 2)
elseif not location then
location = _defaultLocation
end
local path = system.pathForFile( filename, location)
local file = io.open(path, "w")
if file then
local contents = json.encode(t)
file:write( contents )
io.close( file )
return true
else
return false
end
end
function M.loadTable(filename, location)
if location and (not _validLocations[location]) then
error("Attempted to load a table from an invalid location", 2)
elseif not location then
location = _defaultLocation
end
local path = system.pathForFile( filename, location)
local contents = ""
local myTable = {}
local file = io.open( path, "r" )
if file then
-- read all contents of file into a string
local contents = file:read( "*a" )
myTable = json.decode(contents);
io.close( file )
return myTable
end
return nil
end
function M.changeDefault(location)
if location and (not location) then
error("Attempted to change the default location to an invalid location", 2)
elseif not location then
location = _realDefaultLocation
end
_defaultLocation = location
return true
end
function M.print_r ( t )
local print_r_cache={}
local function sub_print_r(t,indent)
if (print_r_cache[tostring(t)]) then
print(indent.."*"..tostring(t))
else
print_r_cache[tostring(t)]=true
if (type(t)=="table") then
for pos,val in pairs(t) do
if (type(val)=="table") then
print(indent.."["..pos.."] => "..tostring(t).." {")
sub_print_r(val,indent..string.rep(" ",string.len(pos)+8))
print(indent..string.rep(" ",string.len(pos)+6).."}")
elseif (type(val)=="string") then
print(indent.."["..pos..'] => "'..val..'"')
else
print(indent.."["..pos.."] => "..tostring(val))
end
end
else
print(indent..tostring(t))
end
end
end
if (type(t)=="table") then
print(tostring(t).." {")
sub_print_r(t," ")
print("}")
else
sub_print_r(t," ")
end
print()
end
M.printTable = M.print_r
return M
Usage
local loadsave = require("loadsave")
myTable = {}
myTable.musicOn = false
myTable.soundOn = true
loadsave.saveTable(myTable, "myTable.json")
I am creating a game and need to write the gamedata to a file. I have the game creating the file if its not there and reading the contents of the file (That I put in manually) but I can not get it to write to the file.
local path = system.pathForFile("gameData.gameData", system.DocumentsDirectory)
local myFile
defaultGameData = "It Worked"
if (path) then
myFile = io.open(path, "r")
end
if(myFile) then
print('file')
else
myFile:close()
--io.close(myFile)
myFile = io.open(path, 'w')
myFile:write( "My Test" )
io.close(myFile)
end
myFile = nil
That part works. i then move to the next scene and attempt to write something new
local saveData = "My app state data"
local path = system.pathForFile("gameData.gameData", system.DocumentsDirectory)
local myfile = io.open( path, "w" )
myfile:write( saveData )
io.close( myfile )
But get the error
mainMenu.lua:43: attempt to index local 'myfile' (a nil value)
I know the file is there in the sandbox, and this code was copied from the corona docs. What am I doing wrong???
here are two functions I am using
function SaveTable(t, filename)
local path = system.pathForFile( filename, system.DocumentsDirectory)
local file = io.open(path, "w")
if file then
local contents = JSON.encode(t)
file:write( contents )
io.close( file )
return true
else
return false
end
end
function LoadTable(filename, dir)
if (dir == nil) then
dir = system.DocumentsDirectory;
end
local path = system.pathForFile( filename, dir)
local contents = ""
local myTable = {}
local file = io.open( path, "r" )
if file then
-- read all contents of file into a string
local contents = file:read( "*a" )
myTable = JSON.decode(contents);
io.close( file )
return myTable
end
return nil
end
Usage:
local t = {
text = "Sometext",
v = 23
};
SaveTable(t, "filename.json");
local u = LoadTable("filename.json");
print(u.text);
print(u.v);
Enjoy!
The error occurs due to the mistake in your code line:
myFile:close()
So either comment the line as:
--myFile:close()
Or do as below (only if you need):
myFile = io.open(path, 'w')
myFile:close()
Keep Coding............. :)
I found the solution. I opened the file to read to see if the file exists. I forgot to close it again before I reopened it in the if statement if the file did exist. I only closed it if it didnt exist.
I would like to learn by developing a help function. The code below outlines my plan, and it can be summarized as:
For functions defined in Lua files - look for comments in the source.
For built-in functions and DLLs - look for a text file in .\help\function.txt.
For libraries (if no comments in the source) - look for a text file in .\lib\help\function.txt.
At the end of my code you can see an attempt to build an index of function names using their unique tostring(function) return value. Surely I should be able to do this in a loop?
function learn()
-- learn()
-- Make it easier to learn Lua, based upon Matlab console functions
-- help() print for help text in function source or help directory
-- who() print defined variables (exlcuding those in loaded modules)
-- what() print defined functions (exlcuding those in loaded modules)
-- which() print path to function source file if present
-- list() print the file to the console
-- edit() edit "filename" or function source if present
-- note: edit(_) can be used after any call to list(), help(func),
-- Helper functions
-- table.name() returns table name as string
-- table.length() this is difficult
-- table.keylist() returns a list of keys
-- table.keytype() returns a list of key types
-- edit_source() process function names
-- edit_new() create new "filename" (will use but not make subdirectories)
-- string.split() returns a table from a string
-- io.exists() test if a filename exists
-- io.newfile() creates an empty file
--
-- global variables
-- editor = "P:\\MyPrograms\\EDITORS\\Addins\\Editor2\\editor2.exe "
-- helpindex a list of the names of the inbuilt functions - see end of file
-- topics a table of help topics see topics.lua
-- web = "web"
web = "web"
-- webhelp = "http://www.nongnu.org/gsl-shell/doc/"
webhelp = "http://www.nongnu.org/gsl-shell/doc/"
-- editor = "P:\\MyPrograms\\EDITORS\\Addins\\Editor2\\editor2.exe "
editor = "P:\\MyPrograms\\EDITORS\\Addins\\Editor2\\editor2.exe "
-- required packages
-- lfs - lua file system (binary from lua-files)
require("lfs")
-- topics - for the help system
require("topics")
end
learn()
function who(t,i)
-- who(table)
-- searches the table (or defaults to _G) to print a list of table keys + types
-- the second parameter is to add a prefix for a recursive call to search "sub" tables
-- still having difficulty with the "loaded" table as this is self referencing and sets up an infinate loop!
-- designed for the console, but could be modified to return a table
--
if type(t)~="table" then
t=_G
end
if type(i)~="string" then
i=""
end
local s={}
local u={}
s = table.keylist(t)
u = table.keytype(t)
for k,v in ipairs(s) do
if u[k]=="table" and s[k]~="_G" and s[k]~="loaded" then
who(t[s[k]],i..v..".")
else
if u[k]~="table" and u[k]~="function" and u[k]~="cdata" then
print(u[k], i..v)
end
end
end
end
function what(t,i)
-- what(table)
-- searches the table (or defaults to _G) to print a list of function names
-- the second parameter is to add a prefix for a recursive call to search "sub" tables
-- still having difficulty with the "loaded" table as this is self referencing and sets up an infinate loop!
-- designed for the console, but could be modified to return a table
--
if type(t)~="table" then
t=_G
end
if type(i)~="string" then
i=""
end
local s={}
local u={}
s = table.keylist(t)
u = table.keytype(t)
for k,v in ipairs(s) do
if u[k]=="table" and s[k]~="_G" and s[k]~="loaded" then
what(t[s[k]],i..v..".")
else
if u[k]=="function" then
print(u[k], i..v)
end
end
end
end
function which(funcname)
-- which(funcname)
-- identifies the source for the current definition of funcname
-- designed for the console, but could be modified to return a string
--
if type(funcname)~="function" then return end
local filename = _G.debug.getinfo(funcname).short_src
if filename=="[C]" then
print(tostring(funcname))
else
return filename
end
end
function help(funcname)
-- help(object)
-- for functions prints help text (from source or help\function.txt)
-- adding help text to source as ^--comments is recommended,
-- for builtin functions use a subdirectory from the executable,
-- for uncommented source add a sibling help directory
-- for table prints table name, size and list of contents
-- for variables prints the type of the object
--
if type(funcname)=="boolean" then
io.write("boolean: ")
print(funcname)
return
end
if type(funcname)=="string" then
if funcname=="web" then
os.launch(webhelp)
else
print("string: "..funcname)
end
return
end
if type(funcname)=="number" then
print("number: "..funcname)
return
end
if type(funcname) == 'userdata' then
print(tostring(funcname))
io.write("metadata: ")
print(getmetatable(funcname))
end
if type(funcname) == 'cdata' then
print(tostring(funcname))
-- *** Unfinished
end
if type(funcname)=="table" then
print(tostring(funcname)..", size: "..table.length(funcname))
who(funcname)
what(funcname)
return
end
if type(funcname)=="function" then
-- Test for a source file
local filename = _G.debug.getinfo(funcname).short_src
if io.exists(filename) then
local codestart = _G.debug.getinfo(funcname).linedefined
local codeend = _G.debug.getinfo(funcname).lastlinedefined
if codestart < 1 then
print("Start is less than 1")
codestart = 1
end
if codeend< 1 then
print("End is less than 1")
codeend= 100
end
-- Try to read comments from the source
local output = 0
local count = 0
for line in io.lines(filename) do
count = count+1
if count > codestart and count < codeend then
if line:match("^%-%-") then
print(line)
output = output + 1
end
end
end
if output>0 then
io.write("From : ")
return filename -- to be used with edit(_)
end
-- Test for a help file as a sibling of the source
if output==0 then
-- No comments in the source file so look for a help file
local t = string.split(filename, "\\")
local helppath = table.concat(t,"\\",1,table.length(t)-1).."\\help\\"..t[table.length(t)]
helppath = string.gsub(helppath, "%.lua$" , ".txt")
if io.exists(helppath) then
local filename = list(helppath)
io.write("From : ")
return filename -- to be used with edit(_)
else
print("No help in source file : "..filename)
io.write("No help in: ")
return helppath -- to be used with edit_new(_)
end
end
end
-- Test for a help file in the generic help directory
if helpindex[tostring(funcname)] then
local helppath = "help\\"..helpindex[tostring(funcname)]..".txt"
if io.exists(helppath) then
local filename = list(helppath)
io.write("From : ")
return filename -- to be used with edit(_)
else
io.write("Built in function, but no help in: ")
return helppath -- to be used with edit_new(_)
end
else
print("No help index entry for "..tostring(funcname))
return
end
end
end
function list(filename)
if type(filename)=="function" then
print("list will only accept a string with a valid file name")
return
end
if type(filename)~="string" then
print("list will only accept a string with a valid file name")
return
end
if io.exists(filename) then
for line in io.lines(filename) do
print(line)
end
return filename
else
io.write("Can't find file: ")
return filename
end
end
function edit(filename, linenum)
-- edit(filename[, linenum])
-- loads the file into my editor (defined as global editor)
-- the linenum parameter will move the cursor to linenum
-- you will need to edit the global "editor" and the source command line below
-- or download Editor² from http://www.zabkat.com
--
if type(filename)=="function" then
filename = edit_source(filename)
return filename
end
if type(filename)~="string" then return end
if type(linenum)~="number" then linenum=1 end
if io.exists(filename) then
os.launch(editor.." /P /L:"..linenum.." \""..filename.."\"", " /P /L:"..linenum.." \""..filename.."\"")
else
print("To make a new file edit_new('filename')")
io.write("Can't find file: ")
return filename
end
end
function edit_source(funcname)
if type(funcname)~="function" then return end
local filename = _G.debug.getinfo(funcname).short_src
if io.exists(filename) then
local linenum = _G.debug.getinfo(funcname).linedefined
if linenum < 1 then
linenum = 1
end
edit(filename, linenum)
io.write("Editing : ")
return filename
end
end
function edit_new(filename)
if type(filename)~="string" then return end
io.newfile(filename)
edit(filename) -- This will check for a valid file name
io.write("Editing : ")
return filename
end
function table.name(table)
if type(table)~="table" then return end
for k, v in pairs(_G) do
if v == table then
return k
end
end
return nil
end
function table.length(table)
if type(table)~="table" then return end
local len = 0
for _ in pairs(table) do
len = len + 1
end
if type(len)=="number" then
return len
else
return nil
end
end
function table.keylist(table)
if type(table)~="table" then return end
local keylist={}
local n=0
for key in pairs(table) do
n=n+1
keylist[n]=key
end
return keylist
end
function table.keytype(table)
if type(table)~="table" then return end
local keytype={}
local n=0
for key in pairs(table) do
n=n+1
keytype[n]=type(table[key])
end
return keytype
end
function table.tablelist(table)
if type(table)~="table" then return end
local tablelist={}
local n=0
for key in pairs(table) do
if type(table[key])=="table" then
n=n+1
tablelist[n]=key
end
end
return tablelist
end
function string.split(inputstr, sep)
if sep == nil then
sep = "%s"
end
local t={}
local i=1
for str in string.gmatch(inputstr, "([^"..sep.."]+)") do
t[i] = str
i = i + 1
end
return t
end
function io.newfile(filename)
-- io.newfile(filename)
-- Will create a file if this is a valid filename
-- relative paths will work
-- files will not be overwritten
if type(filename)~="string" then
print("This function requires a string")
return
end
if io.exists(filename) then
io.write("This file already exists : ")
return filename
end
file, errormsg = io.open(filename, "w")
if errormsg then
print(errormsg)
else
file:write()
file:close()
io.write("New file created : ")
return filename
end
end
function io.exists(filename)
if type(filename)~="string" then return false end
local f=io.open(filename,"r")
if f~=nil then
io.close(f) return true
else
return false
end
end
function os.launch(command,params)
-- Via a dos box works - but flashes up a dos console
-- would love a way round this problem
command = "start "..command
os.execute(command)
end
helpindex = {
[tostring(assert)] = "assert",
[tostring(collectgarbage)] = "collectgarbage",
[tostring(dofile)] = "dofile",
[tostring(error)] = "error",
[tostring(getfenv)] = "getfenv",
[tostring(getmetatable)] = "getmetatable",
[tostring(ipairs)] = "ipairs",
[tostring(load)] = "load",
[tostring(loadfile)] = "loadfile",
[tostring(loadstring)] = "loadstring",
[tostring(next)] = "next" ,
[tostring(pairs)] = "pairs" ,
[tostring(pcall)] = "pcall" ,
[tostring(rawequal)] = "rawequal" ,
[tostring(rawget)] = "rawget" ,
[tostring(rawset)] = "rawset" ,
[tostring(select)] = "select" ,
[tostring(setfenv)] = "setfenv" ,
[tostring(setmetatable)] = "setmetatable" ,
[tostring(tonumber)] = "tonumber" ,
[tostring(tostring)] = "tostring" ,
[tostring(type)] = "type" ,
[tostring(unpack)] = "unpack" ,
[tostring(xpcall)] = "xpcall" ,
[tostring(coroutine.create)] = "coroutine.create" ,
[tostring(coroutine.resume)] = "coroutine.resume" ,
[tostring(coroutine.running)] = "coroutine.running" ,
[tostring(coroutine.status )] = "coroutine.status ",
[tostring(coroutine.wrap)] = "coroutine.wrap" ,
[tostring(coroutine.yield)] = "coroutine.yield" ,
[tostring(string.byte)] = "string.byte" ,
[tostring(string.char)] = "string.char" ,
[tostring(string.dump)] = "string.dump" ,
[tostring(string.find )] = "string.find",
[tostring(string.format)] = "string.format" ,
[tostring(string.gmatch)] = "string.gmatch" ,
[tostring(string.gsub)] = "string.gsub" ,
[tostring(string.len)] = "string.len" ,
[tostring(string.lower)] = "string.lower" ,
[tostring(string.match)] = "string.match" ,
[tostring(string.rep)] = "string.rep" ,
[tostring(string.reverse)] = "string.reverse" ,
[tostring(string.sub)] = "string.sub" ,
[tostring(string.upper)] = "string.upper" ,
[tostring(table.concat)] = "table.concat" ,
[tostring(table.insert)] = "table.insert" ,
[tostring(table.maxn)] = "table.maxn" ,
[tostring(table.remove)] = "table.remove" ,
[tostring(table.sort)] = "table.sort" ,
[tostring(math.abs)] = "math.abs" ,
[tostring(math.acos)] = "math.acos" ,
[tostring(math.asin)] = "math.asin" ,
[tostring(math.atan)] = "math.atan" ,
[tostring(math.atan2)] = "math.atan2" ,
[tostring(math.ceil)] = "math.ceil" ,
[tostring(math.cos)] = "math.cos" ,
[tostring(math.cosh)] = "math.cosh" ,
[tostring(math.deg)] = "math.deg" ,
[tostring(math.exp)] = "math.exp" ,
[tostring(math.floor)] = "math.floor" ,
[tostring(math.fmod)] = "math.fmod" ,
[tostring(math.frexp)] = "math.frexp" ,
[tostring(math.ldexp)] = "math.ldexp" ,
[tostring(math.log)] = "math.log" ,
[tostring(math.log10)] = "math.log10" ,
[tostring(math.max)] = "math.max" ,
[tostring(math.min)] = "math.min" ,
[tostring(math.modf)] = "math.modf" ,
[tostring(math.pow)] = "math.pow" ,
[tostring(math.rad)] = "math.rad" ,
[tostring(math.random)] = "math.random" ,
[tostring(math.randomseed)] = "math.randomseed" ,
[tostring(math.sin)] = "math.sin" ,
[tostring(math.sinh)] = "math.sinh" ,
[tostring(math.sqrt)] = "math.sqrt" ,
[tostring(math.tan)] = "math.tan" ,
[tostring(math.tanh)] = "math.tanh" ,
[tostring(io.close)] = "io.close" ,
[tostring(io.flush)] = "io.flush" ,
[tostring(io.input)] = "io.input" ,
[tostring(io.lines)] = "io.lines" ,
[tostring(io.open)] = "io.open" ,
[tostring(io.output)] = "io.output" ,
[tostring(io.popen)] = "io.popen" ,
[tostring(io.read)] = "io.read" ,
[tostring(io.tmpfile)] = "io.tmpfile" ,
[tostring(io.type)] = "io.type" ,
[tostring(io.write)] = "io.write" ,
[tostring(os.clock)] = "os.clock" ,
[tostring(os.date)] = "os.date" ,
[tostring(os.difftime)] = "os.difftime" ,
[tostring(os.execute)] = "os.execute" ,
[tostring(os.exit)] = "os.exit" ,
[tostring(os.getenv)] = "os.getenv" ,
[tostring(os.remove)] = "os.remove" ,
[tostring(os.rename)] = "os.rename" ,
[tostring(os.setlocale)] = "os.setlocale" ,
[tostring(os.time)] = "os.time" ,
[tostring(os.tmpname)] = "os.tmpname" ,
[tostring(debug.debug)] = "debug.debug" ,
[tostring(debug.getfenv)] = "debug.getfenv" ,
[tostring(debug.gethook)] = "debug.gethook" ,
[tostring(debug.getinfo)] = "debug.getinfo" ,
[tostring(debug.getlocal)] = "debug.getlocal" ,
[tostring(debug.getmetatable)] = "debug.getmetatable" ,
[tostring(debug.getregistry)] = "debug.getregistry" ,
[tostring(debug.getupvalue)] = "debug.getupvalue" ,
[tostring(debug.setfenv)] = "debug.setfenv" ,
[tostring(debug.sethook)] = "debug.sethook" ,
[tostring(debug.setlocal)] = "debug.setlocal" ,
[tostring(debug.setmetatable)] = "debug.setmetatable" ,
[tostring(debug.setupvalue)] = "debug.setupvalue" ,
[tostring(debug.traceback)] = "debug.traceback" ,
[tostring(module)] = "module" ,
[tostring(package.loadlib)] = "package.loadlib" ,
[tostring(package.seeall)] = "package.seeall" ,
[tostring(print)] = "print" ,
[tostring(require)] = "require" ,
[tostring(graph.fxplot)] = "graph.fxplot"
}
Revised code:
function help(funcname)
-- help(object)
-- for functions prints help text (from source or help\function.txt)
-- adding help text to source as ^--comments is recommended,
-- for builtin functions use a subdirectory from the executable,
-- for uncommented source add a sibling \help directory and function.txt
-- (note that the source file may contain several functions)
-- for table prints table name, size and list of contents
-- for variables prints the type of the object
--
if type(funcname)=="boolean" then
io.write("boolean: ")
print(funcname)
return
end
if type(funcname)=="string" then
if funcname=="web" then
os.launch(webhelp)
else
print("string: "..funcname)
end
return
end
if type(funcname)=="number" then
print("number: "..funcname)
return
end
if type(funcname) == 'userdata' then
print(tostring(funcname))
io.write("metadata: ")
print(getmetatable(funcname))
end
if type(funcname) == 'cdata' then
print(tostring(funcname))
-- *** Unfinished
end
if type(funcname)=="table" then
print(tostring(funcname)..", size: "..table.length(funcname))
who(funcname)
what(funcname)
return
end
if type(funcname)=="function" then
-- Test for a source file
local filename = _G.debug.getinfo(funcname).short_src
if io.exists(filename) then
local codestart = _G.debug.getinfo(funcname).linedefined
local codeend = _G.debug.getinfo(funcname).lastlinedefined
if codestart < 1 then
print("Start is less than 1")
codestart = 1
end
if codeend< 1 then
print("End is less than 1")
codeend= 100
end
-- Try to read comments from the source
local output = 0
local count = 0
for line in io.lines(filename) do
count = count+1
if count > codestart and count < codeend then
if line:match("^%-%-") then
print(line)
output = output + 1
end
end
end
if output>0 then
io.write("From : ")
return filename -- to be used with edit(_)
end
-- Try to read comments from \help\function.txt
if output==0 then
-- No comments in the source file so look for a help file
local t = string.split(filename, "\\")
local helppath = table.concat(t,"\\",1,table.length(t)-1).."\\help\\"..helpindex[funcname]..".txt"
if io.exists(helppath) then
local filename = list(helppath)
io.write("From : ")
return filename -- to be used with edit(_)
else
print("No help in source file : "..filename)
io.write("No help in: ")
return helppath -- to be used with edit_new(_)
end
end
end
-- Test for a help file in the generic help directory
if helpindex[funcname] then
local helppath = "help\\"..helpindex[funcname]..".txt"
if io.exists(helppath) then
local filename = list(helppath)
io.write("From : ")
return filename -- to be used with edit(_)
else
io.write("Built in function, but no help in: ")
return helppath -- to be used with edit_new(_)
end
else
print("No help index entry for "..helpindex[funcname])
return
end
end
end
-- helpindex as a [function literal -> string] mapping of names.
-- many thanks to Ryan Stein
-- http://stackoverflow.com/questions/20269173/lua-help-function-can-i-extract-the-name-of-a-function
helpindex = {}
do
local function indexfn(t, n)
if n == '_G' then n = '' else n = n .. '.' end
for k, v in pairs(t) do
if type(v) == 'function' then
helpindex[v] = n .. k
end
end
end
for k, v in pairs(_G) do -- Iterate all tables in global scope.
if type(v) == 'table' then
indexfn(v, k)
end
end
end
Perhaps this may be what you're looking for:
local helpindex = {}
do
local function indexfn(t, n)
if n == '_G' then n = '' else n = n .. '.' end
for k, v in pairs(t) do
if type(v) == 'function' then
helpindex[v] = n .. k
end
end
end
for k, v in pairs(_G) do -- Iterate all tables in global scope.
if type(v) == 'table' then
indexfn(v, k)
end
end
end
-- helpindex is now a [function literal -> string] mapping of names.
You don't need to convert the functions to strings to use them as table keys, since anything other than nil can be used as a table key in Lua. The functions themselves work just fine.
How do I copy the image files from my resource directory to documents directory?
This is I've tried so far, this is working but the copied image file is not formatted as image file, so I can't use it.
local path = system.pathForFile( "mypicture.png", system.ResourceDirectory )
local cfile = assert(io.open(path, "rb"))
if cfile then
local imagedata = file:read("*a")
io.close(file)
local pathTo = system.pathForFile("mypicture.png", system.DocumentsDirectory)
local file = io.open( pathTo, "w")
file:write( imagedata )
io.close( file )
file = nil
else
return nil
end
Any other way to copy images from the resource directory?
you can try this
--checking if file exist
function doesFileExist( fname, path )
local results = false
local filePath = system.pathForFile( fname, path )
--filePath will be 'nil' if file doesn't exist and the path is 'system.ResourceDirectory'
if ( filePath ) then
filePath = io.open( filePath, "r" )
end
if ( filePath ) then
print( "File found: " .. fname )
--clean up file handles
filePath:close()
results = true
else
print( "File does not exist: " .. fname )
end
return results
end
--copy file to another path
function copyFile( srcName, srcPath, dstName, dstPath, overwrite )
local results = false
local srcPath = doesFileExist( srcName, srcPath )
if ( srcPath == false ) then
return nil -- nil = source file not found
end
--check to see if destination file already exists
if not ( overwrite ) then
if ( fileLib.doesFileExist( dstName, dstPath ) ) then
return 1 -- 1 = file already exists (don't overwrite)
end
end
--copy the source file to the destination file
local rfilePath = system.pathForFile( srcName, srcPath )
local wfilePath = system.pathForFile( dstName, dstPath )
local rfh = io.open( rfilePath, "rb" )
local wfh = io.open( wfilePath, "wb" )
if not ( wfh ) then
print( "writeFileName open error!" )
return false
else
--read the file from 'system.ResourceDirectory' and write to the destination directory
local data = rfh:read( "*a" )
if not ( data ) then
print( "read error!" )
return false
else
if not ( wfh:write( data ) ) then
print( "write error!" )
return false
end
end
end
results = 2 -- 2 = file copied successfully!
--clean up file handles
rfh:close()
wfh:close()
return results
end
--copy 'readme.txt' from the 'system.ResourceDirectory' to 'system.DocumentsDirectory'.
copyFile( "readme.txt", nil, "readme.txt", system.DocumentsDirectory, true )
this is the reference of the code http://docs.coronalabs.com/guide/data/readWriteFiles/index.html#copying-files-to-subfolders
There is error in your code, local imagedata = file:read("*a") must be local imagedata = cfile:read("*a") same in the next line.
Other than that, the code looks valid and should work fine.