🔒 Locked

Call lua function from c++ (not global function)

Started by Aren Mar 17, 2011 at 8:54 AM 6 replies 5.6k views

Original Post

Mar 17, 2011 at 8:54 AM

Hi,
I wound like to provide my program with "class" ability. And the lua class can receive "event" from program.

Following example, My program random to rob money in account. How can I call "Account:Robbed" in my c++ code?
(ResisterEvent is provide from c++)

Code in lua.


 
 
 Account = {};
 Account.__index = Account;
 
 function Account.Create( balance )
 local acnt = {}; -- our new object
 setmetatable( acnt,Account ); -- make Account handle lookup
 acnt.balance = balance; -- initialize our object
 return acnt;
 end
 
 function Account:Withdraw( amount )
 self.balance = self.balance - amount
 end
 
 function Account:Robbed( amount )
 self.balance = self.balance - amount
 end
 
 -- create and use an Account
 acc = Account.Create( 1000 )
 acc:Withdraw( 100 )
 
 ResisterEvent( acc.Robbed );

Vectorian

Mar 17, 2011 at 9:23 AM

In pseudo-code:

lua_getglobal("Account")

lua_getfield(""Robbed")

lua_pushtable()

lua_pushnumber()

lua_call(-3);

lua_pop(2) // pop "Account" global

owl

Mar 17, 2011 at 9:35 AM

Try this:


 lua_getglobal(L, "acc"); // Get the table instance
 lua_getfield(L, -1, "Robbed"); // Get the function
 lua_pushinteger(L, 123); // pass amount parameter value
 lua_pcall(L, 1, 0, 0); // Call the Lua function

Aren

Mar 17, 2011 at 10:56 AM

Hi Vectorian,

My goal is that any user can write his own lua?so in my program I'll never know "Account".

And what means? can you explain more.

Just like the addon system of World of Warcraft. Any one can write his own lua.
two things he can do are...
1. call global function we support
2. receive event from AP

I already done step 1. The Step 2 also ok if receive function is global.


 function OnTimer( time )
 -- 
 end

But in this case, user can not write his own module if he want to handle the event automatic.

In pseudo-code:

lua_getglobal("Account")

lua_getfield(""Robbed")

lua_pushtable()

lua_pushnumber()

lua_call(-3);

lua_pop(2) // pop "Account" global

Aren

Mar 17, 2011 at 10:58 AM

Hi owl,

It just an example, I assume in my program I'll never know the name.

Try this:

lua_getglobal(L, "acc"); // Get the table instance lua_getfield(L, -1, "Robbed"); // Get the function lua_pushinteger(L, 123); // pass amount parameter value lua_pcall(L, 1, 0, 0); // Call the Lua function

owl

Mar 17, 2011 at 11:11 AM

Hi owl,

It just an example, I assume in my program I'll never know the name.
[quote name='owl' timestamp='1300354523' post='4786923']
Try this:

lua_getglobal(L, "acc"); // Get the table instance lua_getfield(L, -1, "Robbed"); // Get the function lua_pushinteger(L, 123); // pass amount parameter value lua_pcall(L, 1, 0, 0); // Call the Lua function

[/quote]

Then you pass it in the RegisterEvent as a string and you'll know.

Aren

Mar 18, 2011 at 2:13 AM

Hi owl,

I know what you want to tell me.

But my requirement is

lua


 
 CTestModule = {};
 CTestModule.__index = CTestModule;
 
 function CTestModule.OnEvent( balance )
 print( "1234" );
 end
 
 function OnEvent( balance )
 print( "4567" );
 end
 
 RegisterEvent( "CTestModule", "OnEvent" );

in c++


 
 lua_getfield( pState, LUA_GLOBALSINDEX, "OnEvent" );
 lua_call( pState, 0, 0 );
 
 lua_getglobal( pState, "CTestModule" );
 lua_getfield( pState, LUA_GLOBALSINDEX, "OnEvent" );
 lua_call( pState, 0, 0 );

my screen print "4567" twice, But I need "1234" & "4567"

Then you pass it in the RegisterEvent as a string and you'll know.

jblue

Mar 18, 2011 at 12:53 PM

You could take a look at "A Dynamic and Flexible Event System for Script-Driven Games" from Lua Gems. It approaches the problem you have with an elegant design for registering and firing events.

Topic Locked

This topic has been locked by a moderator. New replies are not allowed.