It was thus said that the Great Alejandro Reimondo once stated:
Copied to the list becasue I want to share the response to help me find a
way to resolve the problem
Hi Egor,
What does "send messages to functions" mean?
In object paradigm (Object Technology) the only way to interact with an
object is sending messages. We/anObject impact other object sending
messages. To send a message we need a receiver that is the object that
will react to the message sent.
In object ORIENTED languages, e.g. languages that defines entities that
are not objects, the problem impose limitations for changes during the
lifetime of the system (the system is not open in all directions).
In Lua we have tables (that can be used to implement objects) and values.
The values (string, function, boolean, nil) impose rigid semantics and do
not let the system evolve in that corners. The case of Strings in Lua, can
be patched changing the metatable of one string (all strings share the
same metatable). As I know, Functions do not share a standard metatable,
and we can´t apply the same mechanism to extend semantics of functions.
Changing the metatabe of each function is not a solution, because
functions are allocated anytime and anywhere.
With the information & knowledge I have today on Lua, I do not see a way
to extend all functions of a system modifying one object/metatable.
hope the explanation helps to understand what I need to resolve. w/best
regards,
In a quick experiment:
[spc]lucy:~>lua-53
Lua 5.3.4 Copyright (C) 1994-2017 Lua.org, PUC-Rio
x = function(x) return 3 * x + 5 end
y = function(x) return 4 * x - 3 end
print(debug.getmetatable(x))
nil
mt = { }
debug.setmetatable(x,mt)
function: 0x81f9598
print(debug.getmetatable(x))
table: 0x81e7de8
print(debug.getmetatable(y))
table: 0x81e7de8
print(debug.getmetatable(print))
table: 0x81e7de8
print(debug.getmetatable(io.open))
table: 0x81e7de8
It seems that setting the metatable on one function set the metatable on all
functions, so it appears that functions share the same metatable.
-spc
