Re: New feature for lua

[Egor Skriptunoff <egor.skriptunoff@...>]

On Fri, Apr 5, 2019 at 9:12 AM Sergey Kovalev wrote:

Let inroduce new reserved word "pure_function" into lua.

It should work similar to usual function except

all variables used inside are implicitly local

no access to any upvalues or global namespace _G

So it could interact with arguments it was passed.

This allows to isolate parts of code from whole program.

In lua 5.3.4 there is no way to do it.

There is a way.

function pure_function(source_text)

  return assert(load("local _ENV = {}; return "..source_text))()

end

Usage example:

a=1

local b=1

local sandbox = pure_function[[

function (x)

  a=2

  b=2

  return x^2

end

]]

print(sandbox(5)) - will print 25

print("a=",a) -- will print 1

print("b=",b) -- will print 1