RE: stack and arguments of C functions

[Benoit Germain <bgermain@...>]

oops, this one went too fast. Forget it, LUA behaves as I would have
expected, it is just that I was not able to see it right away :-)

>  -----Original Message-----
> From: 	Benoit Germain  
> Sent:	mercredi 30 octobre 2002 11:42
> To:	'LUA'
> Subject:	stack and arguments of C functions
> 
> Hello,
> 
> I have observed the following thing with a lua C function, such as:
> 
> // C
> 
> int f ( lua_State * L )
> {
> 	lua_Number n1 = lua_tonumber ( L , 1 ) ;
> 	lua_Number n2 = lua_tonumber ( L , 2 ) ;
> 
> 	return 0 ;
> }
> 
> lua_register ( L , "f" , f ) ;
> 
> and :
> 
> -- LUA
> 
> f ( 3 )
> 
> 
> if this function is passed a given number of arguments, 
> attempting to get an argument with an absolute index greater 
> than the actual number of received arguments will return the 
> object at that position as long as it is not beyond the 
> absolute top of the stack. Therefore, lua_tonumber ( L , 2 ) 
> will try to convert whatever is in the stack at that 
> position, disregarding the fact that there is only one argument.
> 
> I would have expected all lua_to... functions to behave in 
> that situation as if nil was found at that position.
> 
> What is the official behaviour ? Do C functions have to 
> explicitly check the number of arguments before getting them ?
> 
> 
> Regards,
> 
> Benoit.