Here is a very simple code that didn't work as expected :
function convert(str)
local _,name = string.match(str, [[<a href=(.*)>(%w+)</a>]])
return name
end
print(convert("A"))
print(convert("B"))
print(convert("C"))
I expected :
A
B
C
And got :
A
nil
nil
Can somebody explain me how Lua is working in this case ?
OK, got it...
I put sample values for StackOverflow. Real values had spaces. I transformed the function to
function convert(str)
local _,name = string.match(str, [[<a href=(.*)>(.*)</a>]])
return name
end
Related
This question here seems to tangentially touch upon it but I cannot get it to work. Here is my LUA file:
function conky_myeval()
local myTable = { " Old London :normal:size=7", "Ethnocentric :normal:size=7"}
var1 = myTable[ math.random( #myTable)]
return var1
end
and the related conky part:
${font ${lua conky_myeval}} Hello World!
Thank you for any assistance and I apologize if this has been asked before; The most similar I found I posted above.
I've found it easier to have a lua script pass conky a string that can be parsed by a lua_parse object that then generates the intended object rather than trying to pass a value to the intended object.
In the case of random fonts, I'd do something like the following, which worked when tested.
Lua file:
function conky_myfont()
local myTable = {"DejaVu Serif:normal:size=12", "MuseJazz Text:normal:size=12"}
var1 = myTable[ math.random( #myTable)]
return "${font "..var1.."}"
end
Conky part:
${lua_parse conky_myfont}Hello World!${font}
local bigDaddy = 'bruh'
if bigDaddy ~= true then
for i=1, 3 do
bigDaddy = typeof(bigDaddy) ~= 'string' and 'bruh'..i or 1
end
end
friend gave me as a challenge but I cant seem to get anywhere, any help?
In Lua typeof isn't a predefined function. To get the type of a value, the type function should be used instead.
Ok so I've been searching for a while and didn't get the answer. I imagine someone has this same problem but I was not able to solve this problem. I'm new to Lua, having some experience with Python but not being a programmer :S.
So I'm doing a metatable to handle complex numbers, following the tutorials here: http://www.dcc.ufrj.br/~fabiom/lua/
so I implement creation, addition, printing and equal comparison:
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(c1+c2.real,c2.im)
end
if 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 eq(c1,c2)
return (c1.real==c2.real) and (c1.im==c2.im)
end
local function modulus(c)
return (math.sqrt(c.real^2 + c.im^2))
end
local function tos(c)
return tostring(c.real).."+"..tostring(c.im).."i"
end
mt.new=new
mt.__add=add
mt.__tostring=tos
mt.__eq=eq
mt.__len=modulus
return mt
Then I make a small tests:
complex2=require "complex2"
print (complex2)
c1=complex2.new(3,2)
c2=complex2.new(3,4)
print (c1)
print (c2)
print(#{1,2})
print(#c2)
print(complex2.__len(c2))
print(#complex2.new(4,3))
and I get:
table: 0000000003EADBC0
3+2i
3+4i
2
0
5
0
So, What am I dong wrong? is something with calling the #, when i try to debug in the other cases the program goes to the module into the function but the # operand gets like ignored. Modulus function is working and can be called in the module... I'm sorry for such a long and I'm sure obvious question but I tried everything I could already. Thank you
May be the problem is about Lua version.
http://www.lua.org/manual/5.2/manual.html#2.4
"len": the # operation
works since Lua 5.2
and it works only with tables
So, Thank you, and you are right. I thought I had selected 5.2 but in the interpreter it was running 5.1 :S. Now i did:
complex2=require "complex2"
print (complex2)
c1=complex2.new(3,2)
c2=complex2.new(3,4)
print (c1)
print (c2)
print (c1+c2)
print(#{1,2})
print(#c2)
print(complex2.__len(c2))
print(complex2.__len(complex2.new(3,3)))
print(#complex2.new(4,3))
print(getmetatable(c2))
And i got:
table: 000000000047E1C0
3+2i
3+4i
6+6i
2
5
5
4.2426406871193
5
table: 000000000047E1C0
Everything under control ^^, at least the code was working as supposed xD
When call a lua function like
PrintMe(MyVariableName)
I would like to be able to actually print "MyVariableName" and not it's value(well, for demo purposes).
Obviously I could just pass the string but that requires extra quotes and I also would like to print it's value.
e.g.,
MyVariable = 4
PrintVariable(MyVariable)
Would print "MyVariable is 4" or whatever
I do not want to have to duplicate the name and variable like
PrintVariable(MyVariable, "MyVariable")
as this is unnecessary duplication.
Can lua handle it?
What I'm doing now is passing the variable name in quotes and using loadstring to get the value but I would like to just pass the variable directly without the extra unnecessary quotes(which I thought debug.getlocal did but it ends up returning the value instead of the name).
Here is mock example
function printme1(var, val)
print(var.." = "..val)
end
function printme2(v)
local r
loadstring("r = "..v)() -- equivalent to r = a but must be used since v is a string representing a and not the object a
print(v.." = "..tostring(r))
end
function printme3(v)
-- unknown
end
a = 3
printme1("a", a)
printme2("a")
printme3(a)
In this case all 3 should print the same thing. printme3 obviously is the most convenient.
You can't say PrintVariable(MyVariable), because Lua gives you no way of determining which variable (if any; a constant could have been used) was used to pass an argument to your function. However, you can say PrintVariable('MyVariable') then used the debug API to look for a local variable in the caller's scope which has that name:
function PrintVariable(name)
-- default to showing the global with that name, if any
local value = _G[name]
-- see if we can find a local in the caller's scope with that name
for i=1,math.huge do
local localname, localvalue = debug.getlocal(2,i,1)
if not localname then
break -- no more locals to check
elseif localname == name then
value = localvalue
end
end
if value then
print(string.format("%s = %s", name, tostring(value)))
else
print(string.format("No variable named '%s' found.", name))
end
end
Now you can say:
PrintVariable('MyVariable')
While in this case will print "MyVariable = 4".
Not, if you really want to do this without the quotes, you could check the caller's locals for variables that have a supplied value, but that's occasionally going to give you the wrong variable name if there is more than one variable in the caller's scope with a given value. With that said, here's how you'd do that:
function PrintVariable(value)
local name
-- see if we can find a local in the caller's scope with the given value
for i=1,math.huge do
local localname, localvalue = debug.getlocal(2,i,1)
if not localname then
break
elseif localvalue == value then
name = localname
end
end
-- if we couldn't find a local, check globals
if not name then
for globalname, globalvalue in pairs(_G) do
if globalvalue == value then
name = globalname
end
end
end
if name then
print(string.format("%s = %s", name, tostring(value)))
else
print(string.format("No variable found for the value '%s'.", tostring(value)))
end
end
Now you can say PrintVariable(MyVariable), but if there happened to be another variable in the caller's scope with the value 4, and it occurred before MyVariable, it's that variable name that will be printed.
you can do stuff like this with the debug library... something like this does what you seem to be looking for:
function a_func(arg1, asdf)
-- if this function doesn't use an argument... it shows up as (*temporary) in
-- calls to debug.getlocal() because they aren't used...
if arg1 == "10" then end
if asdf == 99 then end
-- does stuff with arg1 and asdf?
end
-- just a function to dump variables in a user-readable format
function myUnpack(tbl)
if type(tbl) ~= "table" then
return ""
end
local ret = ""
for k,v in pairs(tbl) do
if tostring(v) ~= "" then
ret = ret.. tostring(k).. "=".. tostring(v).. ", "
end
end
return string.gsub(ret, ", $", "")
end
function hook()
-- passing 2 to to debug.getinfo means 'give me info on the function that spawned
-- this call to this function'. level 1 is the C function that called the hook.
local info = debug.getinfo(2)
if info ~= nil and info.what == "Lua" then
local i, variables = 1, {""}
-- now run through all the local variables at this level of the lua stack
while true do
local name, value = debug.getlocal(2, i)
if name == nil then
break
end
-- this just skips unused variables
if name ~= "(*temporary)" then
variables[tostring(name)] = value
end
i = i + 1
end
-- this is what dumps info about a function thats been called
print((info.name or "unknown").. "(".. myUnpack(variables).. ")")
end
end
-- tell the debug library to call lua function 'hook 'every time a function call
-- is made...
debug.sethook(hook, "c")
-- call a function to try it out...
a_func("some string", 2012)
this results in the output:
a_func(asdf=2012, arg1=some string)
you can do fancier stuff to pretty this up, but this basically covers how to do what you're asking.
I have bad news, my friend. You can access function parameter names as they appear at the top of the function, but the data to access exactly what they were named in the calling function does not exist. See the following:
function PrintVariable(VariableToPrint)
--we can use debug.getinfo() to determine the name 'VariableToPrint'
--we cannot determine the name 'MyVariable' without some really convoluted stuff (see comment by VBRonPaulFan on his own answer)
print(VariableToPrint);
end
MyVariable = 4
PrintVariable(MyVariable)
To illustrate this, imagine if we had done:
x = 4
MyVariable = x
MyOtherVariable = x
x = nil
PrintVariable(MyVariable)
Now if you were Lua, what name would you attach in the metadata to the variable that ends up getting passed to the function? Yes, you could walk up the stack with debug.getint() looking for the variable that was passed in, but you may find several references.
Also consider:
PrintVariable("StringLiteral")
What would you call that variable? It has a value but no name.
You could just use this form:
local parms = { "MyVariable" }
local function PrintVariable(vars)
print(parms[1]..": "..vars[1])
end
local MyVariable = "bar"
PrintVariable{MyVariable}
Which gives:
MyVariable: bar
It isn't generic, but it is simple. You avoid the debug library and loadstring by doing it this way. If your editor is any good, you could write a macro to do it.
Another possible solution is add this facility your self.
The Lua C API and source is pretty simple and extendable.
I/we don't know the context of your project/work but if you ARE making/embedding your own Lua build you could extend the debug library with something to do this.
Lua passes it's values by reference, but unknown offhand if these contain a string name in them and if so if easily accessible.
In your example the value declaration is the same as:
_G["MyVariable"] = 4
Since it's global. If it were declared local then like others stated here you can enumerate those via debug.getlocal(). But again in the C context of the actual reference context it might not matter.
Implement a debug.getargumentinfo(...) that extends the argument table with name key, value pairs.
This is quite an old topic and I apologize for bringing it back to life.
In my experience with lua, the closest I know to what the OP asked for is something like this:
PrintVariable = {}
setmetatable(PrintVariable, {__index = function (self, k, v) return string.format('%s = %s', k, _G[k]) end})
VAR = 0
VAR2 = "Hello World"
print(PrintVariable.VAR, PrintVariable.VAR2)
-- Result: VAR = 0 VAR2 = Hello World
I do not give more explanation, because the code is quite readable, however:
What happens here is simple, you only set a metatable to the PrintVariable variable and add the __index metamethod that is called when the table is forced to search for a value in its index, thanks to this functionality you can achieve what you see in the example.
Reference: https://www.lua.org/manual/5.1/manual.html
I hope that future and new visitors will find this helpful.
This is a WoW (World of Warcraft) lua script question. Not many of these get asked here but I have no where to turn and Stackoverflow is the programmer oasis for answers.
Question:
Wowwiki states that the 2nd, 3rd, 4th arguments are your calling functions 1st, 2nd, 3rd arguments. I don't find this to be true. I find that the 3rd, 4th, 5th arguments end up being the 1st, 2nd, 3rd arguments.
Link: http://www.wowwiki.com/API_pcall
Function:
function myTest(arg1)
return arg1 .. 10;
end
Problem:
local retOK, ret1 = pcall(myTest,"string value");
when I try the sample I get an error of "trying to perform concatenate on local 'arg1' (a nil value)". If I change the code to:
local retOK, ret1 = pcall(myTest,"string value", "bob");
then I get the output of "bob10". Where does the 2nd argument go and what is it for?
More Testing:
function BobsToolbox:RunTest()
local test1, value1 = pcall(BobsToolbox.Test1, "string value");
SharpDeck:Print("Test1: " .. tostring(test1) .. " Value: " .. tostring(value1));
end
function BobsToolbox:Test1(arg1)
return arg1 .. "10";
end
Results: attempt to concatenate local 'arg1' (a nil value)
function BobsToolbox:RunTest()
local test1, value1 = pcall(Test1, "string value");
SharpDeck:Print("Test1: " .. tostring(test1) .. " Value: " .. tostring(value1));
end
function Test1(arg1)
return arg1 .. "10";
end
Results: string value10
I am new to lua and I can't understand why these are different.
New Question:
The following code works but why?
function BobsToolbox:RunTest()
local test1, value1 = pcall(BobsToolbox.Test1, "string value");
SharpDeck:Print("Test1: " .. tostring(test1) .. " Value: " .. tostring(value1));
end
function BobsToolbox.Test1(arg1)
return arg1 .. "10";
end
What's the difference between the following: ("." vs ":")
function BobsToolbox.Test1(arg1)
function BobsToolbox:Test1(arg1)
Lua Documentation:
http://www.lua.org/pil/16.html
This use of a self parameter is a central point in any object-oriented language. Most OO languages have this mechanism partially hidden from the programmer, so that she does not have to declare this parameter (although she still can use the word self or this inside a method). Lua can also hide this parameter, using the colon operator. We can rewrite the previous method definition as
function Account:withdraw (v)
self.balance = self.balance - v
end
and the method call as
a:withdraw(100.00)
The effect of the colon is to add an extra hidden parameter in a method definition and to add an extra argument in a method call. The colon is only a syntactic facility, although a convenient one; there is nothing really new here. We can define a function with the dot syntax and call it with the colon syntax, or vice-versa, as long as we handle the extra parameter correctly:
Account = { balance=0,
withdraw = function (self, v)
self.balance = self.balance - v
end
}
function Account:deposit (v)
self.balance = self.balance + v
end
Account.deposit(Account, 200.00)
Account:withdraw(100.00)
Possible Conclusion:
With this in mind I assume that when calling a ":" function using "pcall" you must supply the "self" argument.
Related: There are nice live code editors for WoW. I used to use LuaSlinger, but turns out that's no longer developed and the developer recommends Hack instead.
However, what you might be encountering here is that the colon method-call syntax is just syntax sugar, ditto for method definitions, IIRC. Basically, if you do foo:bar("quux!"), where foo is an object, you are in reality just doing foo.bar(foo, "quux!").
Hope that helps!
Well, I don't think WoWWiki is wrong. Here is the code I am using:
function myTest(arg1) return arg1 .. 10; end
local retOK, ret1 = pcall(myTest,"string value");
DEFAULT_CHAT_FRAME:AddMessage(ret1);
local retOK, ret1 = pcall(myTest,"string value", "bob");
DEFAULT_CHAT_FRAME:AddMessage(ret1);
Here is the output I get in my General chat box:
string value10
string value10
How are you trying your sample code? I just pasted my code into an existing mod lua file and made sure that mod was enabled in the addons window before selecting my character and logging in. I made a few changes to the source lua file and typed:
/console reloadui
To try the new changes and have the results output to my screen. I don't have much advice to offer you, because I haven't done much work with WoW addons. Have you tried this code in a blank addon to make sure nothing else is interfering? Have you actually tried the code in game? If you can provide any more information or want me to try anything else, let me know!
Update: Decided to try a few more tests. Here are the tests (with the same function):
local retOK, ret1 = pcall(myTest,"");
DEFAULT_CHAT_FRAME:AddMessage(ret1);
local retOK, ret1 = pcall(myTest, nil, "bob");
DEFAULT_CHAT_FRAME:AddMessage(ret1);
And the results:
10
attempt to concatenate local 'arg1' (a nil value)
It's interesting that the error I see when arg1 is nil is slightly different than the error you see. I'd be interested in knowing how you are testing your code. Or maybe you didn't copy the error down verbatim? I guess you could also try clearing out your WTF folder and disabling the rest of your addons to test this function. If it makes a difference, then you can enable them one a time until you find the problem.