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[Wxlua-users] Idea for function overloading
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From: Ray G. <ray...@sc...> - 2006-04-12 23:59:49
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I was thinking that we could implement function overloading by doing the
following
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Give method struct the ability to store function parameter tags
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typedef int* wxLuaArgTag; // address of class tag
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struct WXLUAMETHOD // defines a LUA method or property
{
LuaType type; // type (one of the above
enumeration values)
const char *name; // name of the method or
property
lua_CFunction func; // function that implements the
method or property
int maxargs; // number of params to the
method (required + optional)
int minargs; // number of required params
const char *overloadname; // overloaded method or
property name
const wxLuaArgTag *argtags; // array of method tags (only
required when using overloaded fn name=20
};
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Have a helper function that can redirect c function calls
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// Redirect lua function call to 1 method from a list of overloaded
functions
int LUACALL wxLuaState::CallOverloadedFunction(struct WXLUAMETHOD*
overloadedMethods, int overloadedMethodCount)
{
int tag;
int arg;
int method;
int bestMethod =3D -1;
int invalidArg =3D -1;
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// do nothing
if (!overloadedMethods && overloadedMethodCount =3D=3D 0)
return 0;
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// get number of arguments called from lua
int argCount =3D lua_GetTop();
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for (method =3D 0; method < overloadedMethodCount; method++)
{
// does function version handle argCount Arguments?
if (argCount >=3D overloadedMethods[method].minargs /* && =
argCount
<=3D overloadedMethods[method].maxargs */)
{
bool match =3D true;
for (arg =3D 0; arg < argCount; arg++)
{
// does this method have any more arguments?
if (!overloadedMethods[method].argtags ||
!overloadedMethods[method].argtags[arg])
break;
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// get argument tag id
tag =3D (int)*(overloadedMethods[method].argtags[arg]);
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if (tag =3D=3D s_LuaArgTagString)
{
if (!IsStringType(arg))
{
match =3D false;
break;
}
}
else if (tag =3D=3D s_LuaArgTagBoolean)
{
if (!IsBooleanType(arg))
{
match =3D false;
break;
}
}
else if (tag =3D=3D s_LuaArgTagEnumeration)
{
if (!IsEnumerationType(arg))
{
match =3D false;
break;
}
}
else if (tag =3D=3D s_LuaArgTagNumber)
{
if (!IsNumberType(arg))
{
match =3D false;
break;
}
}
else if (tag =3D=3D s_LuaArgTagLightUserData)
{
if (!lua_IsLightUserData(arg))
{
match =3D false;
break;
}
}
else if (tag =3D=3D s_LuaArgTagUserData)
{
if (!lua_IsUserData(arg))
{
match =3D false;
break;
}
}
else if (tag =3D=3D s_LuaArgTagStringArray)
{
if (!lua_IsTable(arg))
{
match =3D false;
break;
}
}
else if (tag =3D=3D s_LuaArgTagIntArray)
{
if (!lua_IsTable(arg))
{
match =3D false;
break;
}
}
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{
if (!IsUserDataType(arg, tag))
{
match =3D false;
break;
}
}
}
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if (match)
{
// successfully found overloaded function=20
// that can handle wxLua call
return
(*overloadedMethods[method].func)(M_WXLSTATEDATA->m_lua_State);
}
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if (invalidArg < arg)
{
bestMethod =3D method;
invalidArg =3D arg;
}
}
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//
// Build an error message
//
wxString fnName =3D overloadedMethods[0].overloadname;
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wxString fnCall =3D fnName + wxT("(");
for (arg =3D 0; arg < argCount; arg++)
{
if (arg > 0)
fnCall +=3D wxT(", ");
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if (IsBooleanType(arg))
{
fnCall +=3D wxT("boolean");
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}
else if (IsNumberType(arg))
{
fnCall +=3D wxT("number");
}
else if (IsStringType(arg))
{
fnCall +=3D wxT("string");
}
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{
int tag =3D ttag(arg);
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fnCall +=3D lua2wx(GetLuaTagName(tag));
}
}
fnCall +=3D wxT(")");
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wxString fnOverload =3D wxEmptyString;
for (method =3D 0; method < overloadedMethodCount; method++)
{
wxString fn =3D wxString::Format(wxT("%02d. %s("), method,
fnName.c_str());
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for (arg =3D 0; arg < overloadedMethods[method].maxargs; arg++)
{
// optional args?
if (overloadedMethods[method].minargs <
overloadedMethods[method].maxargs &&
arg =3D=3D overloadedMethods[method].minargs)
{
fn +=3D wxT("[");
}
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if (arg > 0)
fn +=3D wxT(", ");
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tag =3D (int)*overloadedMethods[method].argtags[arg];
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if (tag =3D=3D s_LuaArgTagString)
{
fn +=3D wxT("string");
}
else if (tag =3D=3D s_LuaArgTagBoolean)
{
fn +=3D wxT("boolean");
}
else if (tag =3D=3D s_LuaArgTagEnumeration)
{
fn +=3D wxT("enum");
}
else if (tag =3D=3D s_LuaArgTagNumber)
{
fn +=3D wxT("number");
}
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{
fn +=3D lua2wx(GetLuaTagName(tag));
}
}
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// close optional args
if (overloadedMethods[method].minargs <
overloadedMethods[method].maxargs)
{
fn +=3D wxT("]");
}
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fn +=3D wxT(")");
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fnOverload +=3D fn + wxT("\n");
}
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wxString errmsg;
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if (bestMethod =3D=3D -1)
errmsg =3D wxString::Format(wxT("wxLua %s has invalid
argument\n%s"), fnCall.c_str(), fnOverload.c_str());
else
errmsg =3D wxString::Format(wxT("wxLua %s has invalid argument =
%d
on method %d\n%s"), fnCall.c_str(), invalidArg, bestMethod,
fnOverload.c_str());
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terror(errmsg);
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return 0;
}
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Have the binding do something like
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// Overloaded Functions
static int LUACALL wxEraseEvent_wxEraseEvent(lua_State *L)
{
static WXLUAMETHOD overloaded_wxEraseEvent_methods[] =3D
{
{ LuaConstructor, "wxEraseEventFromInt",
wxEraseEventFromInt_constructor, 2, 0, "wxEraseEvent", {
&s_LuaArgTagNumber,&s_wxDC,0 } },
{ LuaConstructor, "wxEraseEventCopy",
wxEraseEventCopy_constructor, 1, 1, "wxEraseEvent", { &s_wxEraseEvent,0
} },
};
static int overloaded_wxEraseEvent_methodCount =3D
sizeof(overloaded_wxEraseEvent_methods)/sizeof(WXLUAMETHOD);
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wxLuaState wxlState(L);
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return
wxlState.CallOverloadedFunction(overloaded_wxEraseEvent_methods,
overloaded_wxEraseEvent_methodCount);
};
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// Map Lua Class Methods to C Binding Functions
static WXLUAMETHOD s_wxEraseEvent_methods[] =3D {
{ LuaDelete, "wxEraseEvent", wxEraseEvent_destructor, 0, 0, NULL,
NULL },
{ LuaConstructor, "wxEraseEventFromInt",
wxEraseEventFromInt_constructor, 2, 0, "wxEraseEvent", {
&s_LuaArgTagNumber,&s_wxDC,0 } },
{ LuaConstructor, "wxEraseEventCopy", wxEraseEventCopy_constructor,
1, 1, "wxEraseEvent", { &s_wxEraseEvent,0 } },
{ LuaMethod, "GetDC", wxEraseEvent_GetDC, 0, 0, NULL, NULL },
{ LuaMethod, "Clone", wxEraseEvent_Clone, 0, 0, NULL, NULL },
{ LuaGetProp, "DC", wxEraseEvent_GetDC, 0, 0, NULL, NULL },
// Overloaded Functions
{ LuaConstructor, "wxEraseEvent", wxEraseEvent_wxEraseEvent, 0, 0,
NULL, NULL },
};
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// Extern accessor to class method map
WXLUAMETHOD* wxEraseEvent_methods =3D s_wxEraseEvent_methods;
int wxEraseEvent_methodCount =3D
sizeof(s_wxEraseEvent_methods)/sizeof(s_wxEraseEvent_methods[0]);
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Ray
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