I have File: data.lua
#! /usr/bin/env lua
local a = {
b = {
c = {
version = "z.y"
},
d = {
version = "z.w"
},
getcversion = function ( self )
print( self.c.version )
end
}
}
Now I need to 'getcversion()' Function..
a.b:getcversion()
The problem is, I need to call it from the outside:
data.lua "a.b:getcversion()"
I tried everything that I could, but I couldn't solve this..
Does any one knows how I could call 'getcversion()' ?
Thanks in Advance,
Regards
You'll need to add something like the following to your script:
load(arg[1], "<string>", "t", {a = a})()
load will load the content of the passed parameter (arg[1]) and will return the function that will execute that code in a specific environment (provided as {a = a} table), as you need to pass the values of local variables to your code (Lua 5.2+).
Keep in mind that this will allow the caller to pass arbitrary Lua code to your script, which may be a security issue.
The error handling is left as the exercise for the reader.
Add return a to the end of data.lua to turn it into a module, and then:
$ lua -e 'a = require("data"); print(a.b:getcversion())'
z.y
Related
I have a main lua file app.lua , and in that app I have a button to "load data" in.
NOTE: LUA 5.1 not 5.2
The data file is a lua file as well with tables in it.
data1 = {
{a,b,c},
{1,2,3}
}
data2 = {
{d,e,f}
}
The goal was to make those tables available to the app anytime I choose to load the file.
I tried the example from the lua site
function dofile (filename)
local f = assert(loadfile(filename))
return f()
end
but f() is just printing a massive string. I can't seem to access f.data1[1] for example.
The file you're loading is not a data table. That's a piece of code, anonymous function that is executable. You run that code in return f() statement.
But see what that code does - it doesn't return anything. Instead it assigns two global variables, data1 and data2. You can access those as data1[1] for example.
You could return the data in the file being loaded, that way it wouldn't pollute the global environment, and probably will look like you imagined it to be:
return {
data1 = { {a,b,c}, {1,2,3} },
data2 = { d,e,f}
}
And in other file:
local f = assert(loadfile(filename))
my_data = f()
print(my_data.data1[1][1])
I wrote simple class to compress data. Here it is:
LZWCompressor = {}
function LZWCompressor.new()
local self = {}
self.mDictionary = {}
self.mDictionaryLen = 0
-- ...
self.Encode = function(sInput)
self:InitDictionary(true)
local s = ""
local ch = ""
local len = string.len(sInput)
local result = {}
local dic = self.mDictionary
local temp = 0
for i = 1, len do
ch = string.sub(sInput, i, i)
temp = s..ch
if dic[temp] then
s = temp
else
result[#result + 1] = dic[s]
self.mDictionaryLen = self.mDictionaryLen + 1
dic[temp] = self.mDictionaryLen
s = ch
end
end
result[#result + 1] = dic[s]
return result
end
-- ...
return self
end
And i run it by:
local compressor = LZWCompression.new()
local encodedData = compressor:Encode("I like LZW, but it doesnt want to compress this text.")
print("Input length:",string.len(originalString))
print("Output length:",#encodedData)
local decodedString = compressor:Decode(encodedData)
print(decodedString)
print(originalString == decodedString)
But when i finally run it by lua, it shows that interpreter expected string, not Table. That was strange thing, because I pass argument of type string. To test Lua's logs, i wrote at beggining of function:
print(typeof(sInput))
I got output "Table" and lua's error. So how to fix it? Why lua displays that string (That i have passed) is a table? I use Lua 5.3.
Issue is in definition of method Encode(), and most likely Decode() has same problem.
You create Encode() method using dot syntax: self.Encode = function(sInput),
but then you're calling it with colon syntax: compressor:Encode(data)
When you call Encode() with colon syntax, its first implicit argument will be compressor itself (table from your error), not the data.
To fix it, declare Encode() method with colon syntax: function self:Encode(sInput), or add 'self' as first argument explicitly self.Encode = function(self, sInput)
The code you provided should not run at all.
You define function LZWCompressor.new() but call CLZWCompression.new()
Inside Encode you call self:InitDictionary(true) which has not been defined.
Maybe you did not paste all relevant code here.
The reason for the error you get though is that you call compressor:Encode(sInput) which is equivalent to compressor.Encode(self, sInput). (syntactic sugar) As function parameters are not passed by name but by their position sInput inside Encode is now compressor, not your string.
Your first argument (which happens to be self, a table) is then passed to string.len which expects a string.
So you acutally call string.len(compressor) which of course results in an error.
Please make sure you know how to call and define functions and how to use self properly!
Hope someone can make sense of what I'm attempting to figure out, Just don't seem to understand Lua enough to achieve this.
--[[
tbl.a.test("moo") returns "Table A moo appears"
tbl.b.test("moo") returns "moo appears"
]]
tbl = {
a = { ID = "Table A" },
b = {
test = function(...) print(... .. " appears") end,
},
}
tbl.a__index = function(self, ...) tbl.b[self](tbl.a.ID .. ...) end
What I'm attempting to do is I could create several tables a, c, d, e and not have to copy test to each one. When tbl.a.test, tbl.c.test, tbl.d.test is used, It'll retrieve the tbl.a.ID var, then call tbl.b.test(ID, "moo")
So far all I'm finding out is it's not able to find .test on anything other than tbl.b
** EDIT **
Thank's to support so far the code is now;
tbl = {
a = { ID = "Table A " },
b = { test = function(...) local id, rest = ... print(id .. ": " .. rest) end },
}
setmetatable(tbl.a, {__index=function(self, k, ...) local rest = ... return tbl.b[k](tbl.a.ID, rest) end})
However, the ... is not being progressed for some odd reason :|
You're missing a period between tbl.a and __index.
__index needs to be on a's metatable, not the table itself.
You don't return anything from your __index function
self in the __index function is the table being indexed, not the key (which is the second argument)
This should work:
setmetatable(tbl.a, {__index=function(self, k) return tbl.b[k](tbl.a.ID) end})
--------------------------------------------------------------------------------
-- [Sub]Class creation
--------------------------------------------------------------------------------
function newclass(new_obj,old_obj)
old_obj = old_obj or {} --use passed-in object (if any)
new_obj = new_obj or {}
assert(type(new_obj) == 'table','New Object/Class is not a table')
assert(type(old_obj) == 'table','Old Object/Class is not a table')
old_obj.__index = old_obj --store __index in parent object (optimization)
return setmetatable(new_obj,old_obj) --create 'new_obj' inheriting 'old_obj'
end
--------------------------------------------------------------------------------
prototype = {
test = function(self,s) print('Table ' .. self.id .. ' ' .. s .. ' appears') end
}
tbl = {}
tbl.a = newclass({id = 'A'},prototype)
tbl.b = newclass({id = 'B'},prototype)
tbl.a:test('moo')
tbl.b:test('moo')
The distinction between class and object in Lua is only theoretical. In practice they are implemented exactly the same way.
Anytime you need to do inheritance, you can use my general-purpose newclass() function to either create a new class/object, or inherit from an existing one.
Any common code & data you would like to have passed on should go into the 'prototype' table (whatever you'd like to call it for each case).
Also, you seem to forget to use the method calling syntax (that uses a colon instead of a dot) when calling methods. Without it, the self parameter is not automatically recognized.
I have a variable in groovy like below:
project.Map
{
time.'1 1 * ?' = ['T1']
time.'2 1 * ?' = ['T2']
templates.'T1' = ['Z','X','Y']
templates.'T2' = ['Q']
}
Sorry but I am new to groovy ,when i try to access the individual
variable values in project.map how do i access them
i tried something like below
log.info(grailsApplication.config.project.Map.time[1])
log.info(grailsApplication.config.project.Map.get('time.'2 1 * ?'' ))
log.info(grailsApplication.config.project.Map.get('time[0]' ))
log.info(grailsApplication.config.project.Map.time.get('1 1 * ?'))
but they all print null value or object references.how do i access values for
time and templates both within a for loop and without it.
please see http://grails.org/doc/latest/guide/conf.html#config for the ways the config is allowed to nest. your outer syntax is especially mentioned to not be allowed:
However, you can't nest after using the dot notation. In other words, this won't work:
// Won't work!
foo.bar {
hello = "world"
good = "bye"
}
You have to write it as
project { Map { ... } }
The inner dotted parts (with the assignment) are ok (according to the doc)
I have a lua file whose content is lua Table as below:
A={},
A.B={},
A.B.C=0;,
The problem is I want to add prefix XYZ before each above statements. So after the parse the database should have something loke this:
XYZ.A={},
XYZ.A.B={},
XYZ.A.B.C={},
Any ideas? Thanks in advance
You can load the file with XYZ as is environment: loadfile("mydata","t",XYZ). See loadfile in the manual.
This works in Lua 5.2. For Lua 5.1, use loadfile followed by setfenv.
If you can afford polluting your global space with A, simply assign it later:
-- load the file
-- if XYZ doesn't exist, XYZ = { A = A } would be probably shorter
XYZ.A = A
A = nil
I think this is what you want:
XYZ = {}
XYZ.A = {}
XYZ.A.B = {}
XYZ.A.B.C = 0
How about you simply do:
XYZ = {
A = {
B = {
C = 0
}
}
}
If you don't want to nest objects so deep then you may do:
XYZ = {
A = A
}
A = nil
This assumes that you have already declared the object A before.