github.com/dnestorov/luar
Package luar provides a convenient interface between Lua and Go. It uses Alessandro Arzilli's golua (https://github.com/aarzilli/golua). Most Go values can be passed to Lua: basic types, strings, complex numbers, user-defined types, pointers, composite types, functions, channels, etc. Conversely, most Lua values can be converted to Go values. Composite types are processed recursively. Methods can be called on user-defined types. These methods will be callable using _dot-notation_ rather than colon notation. Arrays, slices, maps and structs can be copied as tables, or alternatively passed over as Lua proxy objects which can be naturally indexed. In the case of structs and string maps, fields have priority over methods. Use 'luar.method(<value>, <method>)(<params>...)' to call shadowed methods. Unexported struct fields are ignored. The "lua" tag is used to match fields in struct conversion. You may pass a Lua table to an imported Go function; if the table is 'array-like' then it is converted to a Go slice; if it is 'map-like' then it is converted to a Go map. Pointer values encode as the value pointed to when unproxified. Usual operators (arithmetic, string concatenation, pairs/ipairs, etc.) work on proxies too. The type of the result depends on the type of the operands. The rules are as follows: - If the operands are of the same type, use this type. - If one type is a Lua number, use the other, user-defined type. - If the types are different and not Lua numbers, convert to a complex proxy, a Lua number, or a Lua string according to the result kind. Channel proxies can be manipulated with the following methods: - close(): Close the channel. - recv() value: Fetch and return a value from the channel. - send(x value): Send a value in the channel. Complex proxies can be manipulated with the following attributes: - real: The real part. - imag: The imaginary part. Slice proxies can be manipulated with the following methods/attributes: - append(x ...value) sliceProxy: Append the elements and return the new slice. The elements must be convertible to the slice element type. - cap: The capacity of the slice. - sub(i, j integer) sliceProxy: Return the sub-slice that ranges from 'i' to 'j' included. This matches Lua's behaviour, but not Go's. String proxies can be browsed rune by rune with the pairs/ipairs functions. These runes are encoded as strings in Lua. String proxies can be manipulated with the following method: - sub(i, j integer) sliceProxy: Return the sub-string that ranges from 'i' to 'j' included. This matches Lua's behaviour, but not Go's. Slices must be looped with 'ipairs'.
Readme
Luar is designed to make using Lua from Go more convenient. Go structs, slices and maps can be automatically converted to Lua tables and vice-versa. The resulting conversion can either be a copy or a proxy. In the latter case, any change made to the result will reflect on the source.
Any Go function can be made available to Lua scripts, without having to write C-style wrappers.
Luar support cyclic structures (map[string]interface{}, lists, etc.).
User-defined types can be made available to Lua as well: their exported methods can be called and usual operations such as indexing or arithmetic can be performed.
See the documentation for usage instructions and examples.
Install with
go get <repo>/luar
The original Luar uses Alessandro Arzilli's golua. This fork of Luar uses D.Nestorov's golua. See golua's homepage for further installation details.
This is a fork of https://github.com/stevedonovan/luar that runs with Lua 5.3.3 and supports FFI (https://github.com/dnestorov/luaffifb). The FFI interface is a fork from Facebook's luaffifb (https://github.com/facebook/luaffifb). The only difference is that the former builds a static library with Premake.
The final results is:
package main
import (
"fmt"
"log"
"github.com/dnestorov/luar"
)
var lcode = `
local ffi = require("ffi")
ffi.cdef[[
int printf(const char *fmt, ...);
]]
ffi.C.printf("Hello %s from FFI!\n", "world")
print("Hello world from Lua!")
Print("Hello world from Go!")
`
func main() {
l := luar.Init()
defer l.Close()
l.OpenFFI()
luar.Register(l, "", luar.Map{
// Go functions may be registered directly.
"Print": fmt.Println,
})
err := l.DoString(lcode)
if err != nil {
log.Fatal(err)
}
}
An example REPL is available in the cmd folder.
The GoToLua and LuaToGo functions take a reflect.Type parameter, which is
bad design. Sadly changing this would break backward compatibility.
FAQs
Package luar provides a convenient interface between Lua and Go. It uses Alessandro Arzilli's golua (https://github.com/aarzilli/golua). Most Go values can be passed to Lua: basic types, strings, complex numbers, user-defined types, pointers, composite types, functions, channels, etc. Conversely, most Lua values can be converted to Go values. Composite types are processed recursively. Methods can be called on user-defined types. These methods will be callable using _dot-notation_ rather than colon notation. Arrays, slices, maps and structs can be copied as tables, or alternatively passed over as Lua proxy objects which can be naturally indexed. In the case of structs and string maps, fields have priority over methods. Use 'luar.method(<value>, <method>)(<params>...)' to call shadowed methods. Unexported struct fields are ignored. The "lua" tag is used to match fields in struct conversion. You may pass a Lua table to an imported Go function; if the table is 'array-like' then it is converted to a Go slice; if it is 'map-like' then it is converted to a Go map. Pointer values encode as the value pointed to when unproxified. Usual operators (arithmetic, string concatenation, pairs/ipairs, etc.) work on proxies too. The type of the result depends on the type of the operands. The rules are as follows: - If the operands are of the same type, use this type. - If one type is a Lua number, use the other, user-defined type. - If the types are different and not Lua numbers, convert to a complex proxy, a Lua number, or a Lua string according to the result kind. Channel proxies can be manipulated with the following methods: - close(): Close the channel. - recv() value: Fetch and return a value from the channel. - send(x value): Send a value in the channel. Complex proxies can be manipulated with the following attributes: - real: The real part. - imag: The imaginary part. Slice proxies can be manipulated with the following methods/attributes: - append(x ...value) sliceProxy: Append the elements and return the new slice. The elements must be convertible to the slice element type. - cap: The capacity of the slice. - sub(i, j integer) sliceProxy: Return the sub-slice that ranges from 'i' to 'j' included. This matches Lua's behaviour, but not Go's. String proxies can be browsed rune by rune with the pairs/ipairs functions. These runes are encoded as strings in Lua. String proxies can be manipulated with the following method: - sub(i, j integer) sliceProxy: Return the sub-string that ranges from 'i' to 'j' included. This matches Lua's behaviour, but not Go's. Slices must be looped with 'ipairs'.
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