Export C Function To Lua Command
Wow Lua Functions
Export C Function To Lua Code
Lua Call C Function
Lua Function Definition
Lua C Function

Next:

Lua C API The most direct method to bind to Lua is with the Lua C API. The C API consists of two parts: the basic API (lua.h) provides the primitive functions for all interactions between C and Lua, while the auxiliary library (lauxlib.h) provides higher-level functions for some common tasks. Keeper states will call it as well, but only if it is a C function (keeper states are not able to execute any user Lua code). Typical usage is twofold: Tweak package.loaders; Load some additional C functions in the global space (of course only a C function will be able to do this). Game.printMessage('You can call C functions from Lua!' ) Lua namespaces have nothing to do with C namespaces. They’re used for logical grouping and convenience mostly. Let’s now call Lua function from C- script.lua sumNumbers = function(a,b) printMessage('You can still call C functions from Lua functions!' ) return a + b end. In function C do stuff 004017D4 ret 4 As the function C returns it now calls RET with an argument 4, again freeing 4 bytes of stack space, cleaning the 32 bit argument passed to it. Lua with.Net integration solutions Based on the knowledge above, there are basically two paths you can take to integrate Lua with.Net. Usually, however, it is useful to have private names in a package, that is, names that only the package itself can use. A convenient way to do that in Lua is to define those private names as local variables. For instance, let us add to our example a private function that checks whether a value is a valid complex number.

5.3 Manipulating Lua ObjectsUp:

Export C Function To Lua Command

5 The Application Program Previous:5.1 Executing Lua Code

5.2 Converting Values between C and Lua

Because Lua has no static type system,all values passed between Lua and C have type

Wow Lua Functions

lua_Object,which works like an abstract type in C that can hold any Lua value.

Lua has automatic memory management, and garbage collection.Because of that, a lua_Object has a limited scope,and is only valid inside the block where it was created.A C function called from Lua is a block,and its parameters are valid only until its end.A good programming practice is to convert Lua objects to C valuesas soon as they are available,and never to store lua_Objects in C global variables.

When C code calls Lua repeatedly, as in a loop,objects returned by these calls accumulate,and may create a memory problem.To avoid this,nested blocks can be defined with the functions:After the end of the block,all lua_Object's created inside it are released.

To check the type of a lua_Object,the following function is available:plus the following macros:All macros return 1 if the object has the given type,and 0 otherwise.

The function lua_type can be used to distinguish betweendifferent kinds of user data; see below.

To translate a value from type lua_Object to a specific C type,the programmer can use:lua_getnumber converts a lua_Object to a float.This lua_Object must be a number or a string convertible to number(see Section 4.2); otherwise, the function returns 0.

https://sapclever.amebaownd.com/posts/23175195. lua_getstring converts a lua_Object to a string (char *).This lua_Object must be a string or a number;otherwise, the function returns 0 (the null pointer).This function does not create a new string, but returns a pointer toa string inside the Lua environment.Because Lua has garbage collection, there is no guarantee that suchpointer will be valid after the block ends.

lua_getcfunction converts a lua_Object to a C function.This lua_Object must have type CFunction;otherwise, the function returns 0 (the null pointer).The type lua_CFunction is explained in Section 5.5.

lua_getuserdata converts a lua_Object to void*.This lua_Object must have type userdata;otherwise, the function returns 0 (the null pointer).

The reverse process, that is, passing a specific C value to Lua,is done by using the following functions:plus the macro:All of them receive a C value,convert it to a correspondent lua_Object,and leave the result on the top of the Lua stack,where it can be assigned to a Lua variable,passed as paramenter to a Lua function, etc (see below). lua_pushliteral is like lua_pushstring,but also puts the string in the Lua literal table.This avoids the string to be garbage collected,and therefore has a better overall performance.As a rule, when the string to be pushed is a literal,lua_pushliteral should be used.

User data can have different tags,whose semantics are defined by the host program.Any positive integer can be used to tag a user data.When a user data is retrieved,the function lua_type can be used to get its tag. Amnesia daniel shimeji.

To complete the set,the value nil or a lua_Object can also be pushed onto the stack,with:

Next:5.3 Manipulating Lua ObjectsUp:5 The Application Program Previous:5.1 Executing Lua Code

EDIT: Part 2

Long time without posting, busy at work, family, etc.

Today I decided to write a bit on Lua and how to integrate it with C++.

Lua is a scripting language with an emphasis on being easily embeddable. Lua isused as the scripting language in Photoshop CS, and World of Warcraft, forexample. So if you are looking into adding scriptability to your C or C++applications Lua is quite suited for the task.

In order to learn Lua (both the language itself and how to embed it into yourapp) I recommend you Programming in Luaby one of the Luaauthors.

You can find tons of tutorials on how to get started with Lua. So I will focushere on how to integrate with C++. Most of the sources I’ve found about Lua -C++ integrations take the approach of frameworks to automatically wrap yourobjects/classes to be usable from within Lua. I find this approach confusing, Ithink it’s better to learn how to do it manually, and that’s what I will dohere.

Step 0. Compile Lua itself

Download Lua 5.2.1 and compile it. Clash of clans. Usually it enough with make macosx ormake linux. That will generate liblua.a, the library that we will link to.

Step 1. Create a simple host app

We need a simple host app. Our host app will simply setup Lua and run a scriptfrom it. This script will have access to a std::queue from the host app. Thiswill illustrate how you can share objects with the Lua part. Later we will takea more complex example.

Let’s start with the basic skeleton of a lua environment with somecommunication with its host:

The Makefile

It uses LUAHOME that should point to the directory containing both liblua.a and the lua*.h files.

The samplehost application

The Lua script

The code explained step by step:

Initialization

That creates a lua_State loads the standard libs in it and also loads the code in luascript.lua.

Adding variables from C++ into Lua

Then it sets a global variable in Lua from C++ code using lua_setglobal. Ifyou don’t know what are the lua_pushxxxx and the Lua stack, etc. I recomentthat you take a look at the Lua Reference Manual and Programming in Lua.More or less Lua and the C++ communicate through the stack that livesin lua_State and there is bunch of function to manipulate that stack. So inorder to set a global in Lua from C++ you must