Using Lua in CPP (Basic Data Type, Pointer and Reference)
The previous introduction is a built-in basic data type in the CPP, however, even if this is the case, the situation will become complicated.
Using the macro lua_register_directclosure, which we have completed before, can only register the function of the parameter in the form of the Value. When there is a pointer and reference (once again, it is currently only for basic data types):
1. If it is a pointer, the intent usually implemented is to pass a result with this pointer. 2, if it is a reference, the same. 3, if it is a const pointer, usually only use const in face char *, the intent of the implementation function is that the contents of this parameter will not change. Other situations generally avoid using a Const pointer. 4. If it is a const reference, this is generally avoided for basic data types.
Each of Lua and CPP allows a function to return multiple values in some way. For CPP, multiple return values are returned by the first and second cases described above, and multiple return values can be directly returned for Lua. :
- in luafunction swap (x, y) TMP = xx = yy = TMP
Return X, Yend
X = 100Y = 200
X, Y = swap (x, y)
Print (x..y)
Program output: 200100
Similarly, in the host program, we can also return multiple values to lua:
INT SWAP (Lua_State * L) {// acquisition two parameters int x = GET (TypeWrapper
// Exchange value int TMP = x; x = y; y = tmp; // Return value Push (L, X) to Lua; Push (L, Y);
/ / Tell Lua how many of the values we returned Return 2;
Now we can call this function in Lua:
X = 100Y = 200
X, Y = swap (x, y)
In our register_proxy function, you can only valid for the basic data type by value, depending on our above analysis, if we can know in the compile period, for a template parameter T: 1, this is a basic data type, or one User-defined data type? 2. Is this a normal pointer or an item? 3, is this a reference? 4. Is this a constant pointer? 5, is this a const reference?
If we can know these, then according to our above analysis, we hope: (only for basic data types) 1. If this is a pointer, we want to return the content referred to by the pointer to Lua. 2, if this is a reference, we want to return the referenced finger to Lua. 3. If this is a const pointer, we want to pass the parameters obtained from the Lua stack to the call function. 4. If this is a const reference, we also want to pass the parameters from the Lua Stack to the call function.
