A Lua type that allows arbitrary C data to be stored in Lua variables. It's used to represent new types created by an application program or a library written in C.
Questions tagged [lua-userdata]
56 questions
9
votes
1 answer
How to register Lua userdata correct from Delphi?
I am still confused about registering Delphi userdata to Lua. To teach me the principle I tried to implement a Date(Time) type.
At the beginning this type should have three functions accessible to Lua:
A new function to create variables of this…
knowledge stacker
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6
votes
1 answer
Lua userdata array access and methods
I am writing in C a userdata type for use in Lua. It has some array-type properties and various methods aswell. Right now if u is of this type, I use u:set(k,v) resp. u:get(k) to access data and e.g. u:sort() as method. For this I set __index to a…
1k5
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6
votes
2 answers
Create new empty userdata from pure Lua
I think I saw somewhere a native function in Lua that can return a new userdata. Does it exist? Is it possible to create custom userdata from normal Lua script?
IS4
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5
votes
2 answers
How free up memory allocated by lua_newuserdata with delete operator?
How can I free memory allocated by lua_newuserdata?
I have a class called Foo, and this class has a constructor and desstructor, and I need execute both, but I don't know how to use the C++ operator delete, because I didn't use new to allocate…
user3312225
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4
votes
2 answers
Lifetime of Lua userdata pointers
If I create a userdata object and stash it in a table, then get a reference to it in C/C++, for how long is that reference valid? Is the reference in C/C++ guaranteed to be valid for as long as the userdata is held in the table in Lua? Or is there…
Tom
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4
votes
1 answer
LuaJ array/list type safety
So using LuaJ.
If I pass, from Java to Lua, a userdata List with type T, Luaj still allows insertion into that array of any type of object via the :add function. For example:
Java code:
import java.util.ArrayList;
import…
Dakusan
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3
votes
2 answers
Accessing Light userdata in Lua
I may be misunderstanding their use or misread the documentation, but how do I access members of a struct or class passed to Lua as light userdata? For example if a vector using the following struct
typedef struct Foo {
int x;
int y;
} Foo;
was…
Lucas
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3
votes
1 answer
What happens if I push userdata twice using the same key?
I would like to know what happens if I push the lightuserdata into the registry twice using the same key.
My Code:
MyData *x, *y; //let's say these are valid pointers
lua_pushstring(L, "my_data");
lua_pushlightuserdata(L, static_cast
Zack Lee
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3
votes
0 answers
Bringing userdata into Lua without C (or how much C do I need to learn to do this)
Hi and thanks in advance. I'm trying to see if there's a way to avoid learning C (which I don't know at all) to turn userdata into a Lua table.
I'm using an application which lets users write addons using Lua scripts. These addons can query the…
Liam
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3
votes
1 answer
When is it allowed to call lua_gc in C++ when also using lua_newuserdata
The below example is just to demonstrate the problem/question; in reality I have functions creating
and returning many different userdata object, and between some of those I may want to call the Lua garbage collector.
Also, I am using Lua version…
Torben T Nielsen
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3
votes
1 answer
Lua - implement userdata iterator
Lua 5.2
I need to iterate an userdata variable.
As I understand, I can do this using getmetatable and __pairs. Like this:
for k, v in getmetatable(userdataVariable).__pairs do
-- someting
end
But I get 'attempt to call a nil value' when I'm…
user64675
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3
votes
1 answer
Create properties and methods Lua C++
This is rather tricky to explain and I could not find anything on this in the documentation or anywhere on the net so I thought this would be a suitable place for this question.
I'm trying to register properties and methods on an object in Lua using…
user3806521
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3
votes
1 answer
Access Lua variables in userdata from the C api
I am working on a project written in C++ which uses Lua as a scripting language.
In order to facilitate debugging we implemented a network debugger which receives Lua code, runs it, encodes the return values in Json and sends that string back.
I…
Lars Kokemohr
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3
votes
1 answer
Lua bindings: table vs userdata
When making Lua bindings for C++ classes, should I return tables or userdata objects?
Does anyone know any of the pros and cons for each method?
Sophie Alpert
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2
votes
3 answers
Delete all of my Lua userdata in C++
I'm wondering if it's possible to access all of the userdata "tables" (is it called userdata tables?) and then delete them from Lua because this is my problem:
a = Object(5, 5)
a:Delete()
a:SetPosition(3,3)
As you can see first I create an object…
user1188404
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