Compile-time macros: Ship . Now this target function should be JIT compiled after this loop is executed. A string "hi" for example can have multiple variables pointing to it. Wow. Some full-instrumentation tools may incur higher overhead, like a cost of . PICO-8 has this nice helper function called foreach (table, func) which will call the function for each item. tinsert . An indirect function call (via dlsym (3)) A direct function call (via a JIT-compiled function) As shown, the last one is the fastest. Lua objects, including strings, get garbage collected if nothing points to them. Values associated with some Fibaro variables are predefined i.e. Lua 5.1 has something similar but it's not called _ENV. The overhead is high to access Lua global data, especially tables and functions. There is the overhead of starting up the program, so this method is typically not so suitable if you need to call the code, say, thousands of times per second. Can templates, MediaWiki pages or parser functions be called from Lua? . Apparently if that method is defined, you can call a table as if it's a function. it probably wouldn't hurt to subtract from those the runtime of a loop calling a (localized) empty function with the same number of iterations. The call rawget (t,i) does a raw access to table t . Despite its name, the debug library is useful for tasks other than debugging. Fennel . The trouble is that most of the time I want to call a method (table-bound function) instead of a function. Neither will start to process until the Lua code has return to is calling C function. In your C callback functions, use lua_rawcall () to call other functions. Yield later reads this C call count to determine if a C boundary is crossed. The role of __call is to make something that is not a function (usually a table) act like a function. Zero overhead: Compiled code should be just as efficient as hand-written Lua. For instance, you can write an application to plot the graph of a function and use Lua to define the functions to be plotted. C++ can return objects to Lua, but there's no mechanism for calling Lua functions from C++ with objects wrapped with the SWIG magic - which is rather obscure, and tangled in static functions within the .cpp files it . Zero overhead: Compiled code should be just as efficient as hand-written Lua. It behaves somewhat like a stack as in [Forth] but with one element. -----Original Message----- From: lua-bounces@bazar2.conectiva.com.br [mailto:lua-bounces@bazar2.conectiva.com.br] On Behalf Of Nguyen Dang Quang Sent: Wednesday, July 19, 2006 12:24 PM To: 'Lua list' Subject: RE: call a function in other script from a script Hi Daniel, My trouble is: In File 2: Function some_other_functions(xxx) End function main() --do . local str1 = "hi" local str2 = "hi" It would make total sense if that's the case, because let's say you did local str1 = "hi" local str2 = "hi" str1 = nil So, in conclusion, calling from Lua to C++ is great. Fennel is a programming language that brings together the speed, simplicity and reach of Lua with the flexibility of a lisp syntax and macro system. The advantage disappears if the expression a is a nested table -- e.g. Both styles have approximately the same overhead: one function call per iteration. To answer: using a single lua_State will be faster if you need to load any standard libraries (the overhead is noticeable). A __call field added to a regular table (x in your example) does nothing. Fennel is a programming language that brings together the speed, simplicity, and reach of Lua with the flexibility of a lisp syntax and macro system.. Full Lua compatibility: Easily call any Lua function or library from Fennel and vice-versa. Lua: --[[ DelayedExecute v1.0.3 by AGD | Description: Small Lua . Calling Titan from Lua (and vice versa) should be very cheap function sum_list(xs: {integer}) : integer local sum: integer = 0 for i: integer = 1, #xs do sum = sum + xs[i] end return sum end A separate node.flashindex() function creates a new Lua closure based on a module loaded into LFS and more specfically its flash-based prototype; whilst this access function is not transparent at a coding level, this is no different functionally than already having to handle lua and lc files and the existing range of load functions (load . I would generally recommend to avoid making high volume calls into Lua. Rust closures are harder for three main reasons: The first is that it is both statically and strongly typed, so we'll need to explicitly annotate these function types. A solution that uses some caching should be used to avoid that, either a Vim global variable updated from an autocmd (such as CursorHold, CursorMoved, CursorMovedI . LuaJIT stated that it's faster than Lua. The callback overhead will be absolutely detrimental for performance. Lua stack arguments are automatically popped and converted to C types, the function is executed, and the return value is then converted back to a Lua type and placed on top the stack. If the Lua function does not have any arguments, there is a way of calling it with much less parsing overhead. function Lua_signal_handler () print ("Hi! Lua → VBScript . The Lua code for computing the sum of all . Calling external programs via the command-line interface, using Lua functions like os.execute() or io.popen(). Here we choose a struct which holds four byte fields, one for each componentof a 4x8 bit RGBA pixel. If you are running each script only once you don't need to use lua_dump/lua_load, just do something like luaL_dofile followed by lua_pcall on the entry function, then move on (ie load the next file). I understand that currently the number of Lua files is limited to 128 (0 to 127). There is the overhead of starting up the program, so this method is typically not so suitable if you need to call the code, say, thousands of times per second. When we perform a virtual function call, knowing which function is called we can infer an offset in the array to use and simply call the correct virtual function pointer. The solution There are four components that make the solution, class registration, object instantiation, member function calling, and garbage collection. Then when the Lua VM is at a safe spot, the hook is call which can then run the Lua function. The os.exit() Lua function call will trigger the lj_cf_os_exit() . lua_sethook () is the only safe Lua function to call from an asynchronous thread (or signal handler) as it just sets a flag in the Lua VM . when a lua script is called, (in luaRedisGenericCommand) it is called via the "call()" function which uses server.lua_client and calls lots of addReply()s. this generates a response like ":3\r\n:4\r\n:5\r\n" which is parsed by the function redisProtocolToLuaType() which puts the integers [3,4,5] onto lua's stack. I tweaked the Lua compiler a smidge to, if a compile-time symbol is defined, have Lua do call-counting profiling for all functions without any function-call overhead; it just adds a fetch,add,store to the start of every function. While OO can also be encoded using closures capturing the instance, it has a big memory cost since one method closure needs to be allocated per object method and per instance (or lazily every . Just keep in mind that 'statusline' is evaluated quite often, so the overhead of using a Lua function call from there might become quite noticeable and produce lag while editing. but again this is function call overhead, only measurable with millions of iterations. A Lua function call can return multiple values. . ① First, load the FFI library and declare the low-level data type. Suppose now that we want to redefine print in Lua: Perhaps our system does not have a stdout and so, instead of printing its arguments, print stores them in a global . That is partly about performance but mostly about engine architecture. It is even the case for actions such as requesting a system restart, as can be seen by the following example: Lua has been used to great effect in a number of similar projects, such as arbitrary re-write rules within the Apache Squid proxy, UDFs in both Redis and Postgres, and other projects. Here is the case: script.lua: . This means you can do anything you can do from C: access all memory, overwrite anything in memory, . When the target application reaches maximum throughput, the cost of sampling is generally under 5% of the throughput. The principle is that every time you write table.insert for example, the Lua interpreter looks up the "insert" entry in the table called table. Fennel . . So templates can call Lua modules, parser functions and pages in MediaWiki namespace. (3) reading out Lua values from Lua stack. Zero overhead: Compiled code should be just . The Lua time usage should be fairly consistent for multiple parses of the exact same input . Share Improve this answer Lua modules are treated like the bodies of Lua functions so that they can both receive arguments and return values. In contrast, the new C_Timer . The baseCcalls is set to the nCcalls + 1 by resume. . On the one hand, it is easier to write the iterator with this second style (although we can recover this easiness with coroutines). These are three different types of function calls: Through the PLT. Any method is ok, unpack4 is the slowest probably because of the function call overhead. because you are producing a bit of overhead by using table.pack, . for some things you might be timing the function call overhead could be fairly significant Native vector math. LuaJIT stated that globals and locals now has the same performance unlike in plain Lua. The program must support a command-line interface. This function returns true if the call was transferred by another user and is not a direct call. And then inside the timed code region, we call it repeatedly for 10 million times. Update 31: The New War; Update 30: Call of the Tempestarii; Update 29: The Heart of Deimos; Update 28: The Deadlock Protocol; Update 27: Empyrean; Update 26: The Old Blood The way to handle this is to hook into the Lua VM in the signal handler. PICO-8 Generic Dispatch with Parameters. local soundit = ( function () local sounds = { a = "ay" , b = "bee" , c = "see" , .. } return function (x) assert ( type (x) == "string" ) return sounds [x] end end ) () And then call this function first for 100 times as a warmup. Some functions in Lua receive a variable number of arguments. Actually, it means _ENV.table.insert - _ENV is where the "global variables" are in Lua 5.2+. However, for counting profiles, Lua code does a decent job. 5. First, it allows two or more parallel iterations. For Animations, we're doing work C-side that allows us to support smoothing, parallel animations, and animation propagation. Functions are functions are functions in Lua, they are all equally fast. Lua provides self, but requires the user to distinguish between a regular function call, string.sub(strname, 2, 3) and a method call strname:sub(2, 3). ② Creating the datastructure with ffi.new () is straightforward — the '?' is a placeholder for the number of elements of avariable-length array. Don't know if other types in lua can have metatables set to them, or if that's just exclusive to tables. Aerospike provides examples of compiling and registering a . Lua can't avoid making some use of the C stack as it supports intermingling of lua_call's from C code with in-language VM calls, which necessarily will use some amount of C stack. 23.3 - Profiles. For a profile with timing, it is better to use the C interface: The overhead of a Lua call for each hook is too high and usually invalidates any measure. Iterative multi-file loader, used to load all Lua modules in a directory and return them as one table. . If you are . Details are given below. . Here is what I want to be able to write in Lua: pipe(1, 100000) { range function(xs) return map(xs, function(x) return x * 3 end) end, function(xs) return filter(xs, is_odd) end, sum } . lua_call (the normal function to call a C / lua using the Lua stack from C) also uses luaD_call. The author works around the issue by gluing strings together to effectively rewrite the pipeline into one nested function call. The returned values are an array of objects, corresponding to Lua multiple returned values. Despite its name, the debug library is useful for tasks other than debugging. Details are given below. This true for timer, network, and other callbacks. Although the overhead to do so is measurable, it is simple. On the other hand, the generator style is more flexible. That overhead might be removed if we made save/restore a built-in operation in Lua. However, creating the same function (closure) over and over again inside a busy loop, . Zero overhead: Compiled code should be just as efficient as hand-written Lua. Fibaro global variables are pre-defined to the Fibaro environment using the Home Center -> Panels -> Variables user interface (note: these are not the same as Lua global variables). Second, Lua functions are dynamically allocated ('boxed'.) It's a bad idea to call a user-defined Lua function from C code millions of times. Full Lua compatibility: Easily call any Lua function or library from Fennel and vice-versa. Calling into Lua and running the square function was about 130 times slower than just calling the C++ function. The reason for choosing Lua is that a Lua script is just-in-time-compiled at run time and callable from a C API, just like OpenCL kernels. To get the perf bit out of the way: the bridging code between C++/Lua has overhead compared to just calling Lua from Lua or calling C++ from C++. . Doing a raw access will not speed up your code (the overhead of a function call kills any gain you could have), but sometimes you need it, as we will see later. At its most basic, LuaAutoC can be used to automatically call C functions from the Lua API. When we want to access a table without invoking its __index metamethod, we use the rawget function. Translating all this to human terms, yielding is only possible when C isn't using the Lua stack for its own calls. . A number of the string functions work like this,for instance, string.findwill return the start index and end index of the match, plus any captures. ① First, load the FFIlibrary and declare the low-level data type.