path: root/generic/tclOOBasic.c

/*
 * tclOOBasic.c --
 *
 *	This file contains implementations of the "simple" commands and
 *	methods from the object-system core.
 *
 * Copyright © 2005-2013 Donal K. Fellows
 *
 * See the file "license.terms" for information on usage and redistribution of
 * this file, and for a DISCLAIMER OF ALL WARRANTIES.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "tclInt.h"
#include "tclOOInt.h"

static inline Tcl_Object *AddConstructionFinalizer(Tcl_Interp *interp);
static Tcl_NRPostProc	AfterNRDestructor;
static Tcl_NRPostProc	DecrRefsPostClassConstructor;
static Tcl_NRPostProc	FinalizeConstruction;
static Tcl_NRPostProc	FinalizeEval;
static Tcl_NRPostProc	NextRestoreFrame;

/*
 * ----------------------------------------------------------------------
 *
 * AddCreateCallback, FinalizeConstruction --
 *
 *	Special version of TclNRAddCallback that allows the caller to splice
 *	the object created later on. Always calls FinalizeConstruction, which
 *	converts the object into its name and stores that in the interpreter
 *	result. This is shared by all the construction methods (create,
 *	createWithNamespace, new).
 *
 *	Note that this is the only code in this file (or, indeed, the whole of
 *	TclOO) that uses NRE internals; it is the only code that does
 *	non-standard poking in the NRE guts.
 *
 * ----------------------------------------------------------------------
 */

static inline Tcl_Object *
AddConstructionFinalizer(
    Tcl_Interp *interp)
{
    TclNRAddCallback(interp, FinalizeConstruction, NULL, NULL, NULL, NULL);
    return (Tcl_Object *) &(TOP_CB(interp)->data[0]);
}

static int
FinalizeConstruction(
    ClientData data[],
    Tcl_Interp *interp,
    int result)
{
    Object *oPtr = (Object *)data[0];

    if (result != TCL_OK) {
	return result;
    }
    Tcl_SetObjResult(interp, TclOOObjectName(interp, oPtr));
    return TCL_OK;
}

/*
 * ----------------------------------------------------------------------
 *
 * TclOO_Class_Constructor --
 *
 *	Implementation for oo::class constructor.
 *
 * ----------------------------------------------------------------------
 */

int
TclOO_Class_Constructor(
    TCL_UNUSED(ClientData),
    Tcl_Interp *interp,
    Tcl_ObjectContext context,
    int objc,
    Tcl_Obj *const *objv)
{
    Object *oPtr = (Object *) Tcl_ObjectContextObject(context);
    Tcl_Obj **invoke, *nameObj;

    if (objc-1 > Tcl_ObjectContextSkippedArgs(context)) {
	Tcl_WrongNumArgs(interp, Tcl_ObjectContextSkippedArgs(context), objv,
		"?definitionScript?");
	return TCL_ERROR;
    } else if (objc == Tcl_ObjectContextSkippedArgs(context)) {
	return TCL_OK;
    }

    /*
     * Make the class definition delegate. This is special; it doesn't reenter
     * here (and the class definition delegate doesn't run any constructors).
     */

    nameObj = Tcl_NewStringObj(oPtr->namespacePtr->fullName, -1);
    Tcl_AppendToObj(nameObj, ":: oo ::delegate", -1);
    Tcl_NewObjectInstance(interp, (Tcl_Class) oPtr->fPtr->classCls,
	    TclGetString(nameObj), NULL, -1, NULL, -1);
    Tcl_DecrRefCount(nameObj);

    /*
     * Delegate to [oo::define] to do the work.
     */

    invoke = (Tcl_Obj **)ckalloc(3 * sizeof(Tcl_Obj *));
    invoke[0] = oPtr->fPtr->defineName;
    invoke[1] = TclOOObjectName(interp, oPtr);
    invoke[2] = objv[objc-1];

    /*
     * Must add references or errors in configuration script will cause
     * trouble.
     */

    Tcl_IncrRefCount(invoke[0]);
    Tcl_IncrRefCount(invoke[1]);
    Tcl_IncrRefCount(invoke[2]);
    TclNRAddCallback(interp, DecrRefsPostClassConstructor,
	    invoke, oPtr, NULL, NULL);

    /*
     * Tricky point: do not want the extra reported level in the Tcl stack
     * trace, so use TCL_EVAL_NOERR.
     */

    return TclNREvalObjv(interp, 3, invoke, TCL_EVAL_NOERR, NULL);
}

static int
DecrRefsPostClassConstructor(
    ClientData data[],
    Tcl_Interp *interp,
    int result)
{
    Tcl_Obj **invoke = (Tcl_Obj **)data[0];
    Object *oPtr = (Object *)data[1];
    Tcl_InterpState saved;
    int code;

    TclDecrRefCount(invoke[0]);
    TclDecrRefCount(invoke[1]);
    TclDecrRefCount(invoke[2]);
    invoke[0] = Tcl_NewStringObj("::oo::MixinClassDelegates", -1);
    invoke[1] = TclOOObjectName(interp, oPtr);
    Tcl_IncrRefCount(invoke[0]);
    Tcl_IncrRefCount(invoke[1]);
    saved = Tcl_SaveInterpState(interp, result);
    code = Tcl_EvalObjv(interp, 2, invoke, 0);
    TclDecrRefCount(invoke[0]);
    TclDecrRefCount(invoke[1]);
    ckfree(invoke);
    if (code != TCL_OK) {
	Tcl_DiscardInterpState(saved);
	return code;
    }
    return Tcl_RestoreInterpState(interp, saved);
}

/*
 * ----------------------------------------------------------------------
 *
 * TclOO_Class_Create --
 *
 *	Implementation for oo::class->create method.
 *
 * ----------------------------------------------------------------------
 */

int
TclOO_Class_Create(
    TCL_UNUSED(ClientData),
    Tcl_Interp *interp,		/* Interpreter in which to create the object;
				 * also used for error reporting. */
    Tcl_ObjectContext context,	/* The object/call context. */
    int objc,			/* Number of arguments. */
    Tcl_Obj *const *objv)	/* The actual arguments. */
{
    Object *oPtr = (Object *) Tcl_ObjectContextObject(context);
    const char *objName;
    int len;

    /*
     * Sanity check; should not be possible to invoke this method on a
     * non-class.
     */

    if (oPtr->classPtr == NULL) {
	Tcl_Obj *cmdnameObj = TclOOObjectName(interp, oPtr);

	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		"object \"%s\" is not a class", TclGetString(cmdnameObj)));
	Tcl_SetErrorCode(interp, "TCL", "OO", "INSTANTIATE_NONCLASS", (char *)NULL);
	return TCL_ERROR;
    }

    /*
     * Check we have the right number of (sensible) arguments.
     */

    if (objc - Tcl_ObjectContextSkippedArgs(context) < 1) {
	Tcl_WrongNumArgs(interp, Tcl_ObjectContextSkippedArgs(context), objv,
		"objectName ?arg ...?");
	return TCL_ERROR;
    }
    objName = TclGetStringFromObj(
	    objv[Tcl_ObjectContextSkippedArgs(context)], &len);
    if (len == 0) {
	Tcl_SetObjResult(interp, Tcl_NewStringObj(
		"object name must not be empty", -1));
	Tcl_SetErrorCode(interp, "TCL", "OO", "EMPTY_NAME", (char *)NULL);
	return TCL_ERROR;
    }

    /*
     * Make the object and return its name.
     */

    return TclNRNewObjectInstance(interp, (Tcl_Class) oPtr->classPtr,
	    objName, NULL, objc, objv,
	    Tcl_ObjectContextSkippedArgs(context)+1,
	    AddConstructionFinalizer(interp));
}

/*
 * ----------------------------------------------------------------------
 *
 * TclOO_Class_CreateNs --
 *
 *	Implementation for oo::class->createWithNamespace method.
 *
 * ----------------------------------------------------------------------
 */

int
TclOO_Class_CreateNs(
    TCL_UNUSED(ClientData),
    Tcl_Interp *interp,		/* Interpreter in which to create the object;
				 * also used for error reporting. */
    Tcl_ObjectContext context,	/* The object/call context. */
    int objc,			/* Number of arguments. */
    Tcl_Obj *const *objv)	/* The actual arguments. */
{
    Object *oPtr = (Object *) Tcl_ObjectContextObject(context);
    const char *objName, *nsName;
    int len;

    /*
     * Sanity check; should not be possible to invoke this method on a
     * non-class.
     */

    if (oPtr->classPtr == NULL) {
	Tcl_Obj *cmdnameObj = TclOOObjectName(interp, oPtr);

	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		"object \"%s\" is not a class", TclGetString(cmdnameObj)));
	Tcl_SetErrorCode(interp, "TCL", "OO", "INSTANTIATE_NONCLASS", (char *)NULL);
	return TCL_ERROR;
    }

    /*
     * Check we have the right number of (sensible) arguments.
     */

    if (objc - Tcl_ObjectContextSkippedArgs(context) < 2) {
	Tcl_WrongNumArgs(interp, Tcl_ObjectContextSkippedArgs(context), objv,
		"objectName namespaceName ?arg ...?");
	return TCL_ERROR;
    }
    objName = TclGetStringFromObj(
	    objv[Tcl_ObjectContextSkippedArgs(context)], &len);
    if (len == 0) {
	Tcl_SetObjResult(interp, Tcl_NewStringObj(
		"object name must not be empty", -1));
	Tcl_SetErrorCode(interp, "TCL", "OO", "EMPTY_NAME", (char *)NULL);
	return TCL_ERROR;
    }
    nsName = TclGetStringFromObj(
	    objv[Tcl_ObjectContextSkippedArgs(context)+1], &len);
    if (len == 0) {
	Tcl_SetObjResult(interp, Tcl_NewStringObj(
		"namespace name must not be empty", -1));
	Tcl_SetErrorCode(interp, "TCL", "OO", "EMPTY_NAME", (char *)NULL);
	return TCL_ERROR;
    }

    /*
     * Make the object and return its name.
     */

    return TclNRNewObjectInstance(interp, (Tcl_Class) oPtr->classPtr,
	    objName, nsName, objc, objv,
	    Tcl_ObjectContextSkippedArgs(context)+2,
	    AddConstructionFinalizer(interp));
}

/*
 * ----------------------------------------------------------------------
 *
 * TclOO_Class_New --
 *
 *	Implementation for oo::class->new method.
 *
 * ----------------------------------------------------------------------
 */

int
TclOO_Class_New(
    TCL_UNUSED(ClientData),
    Tcl_Interp *interp,		/* Interpreter in which to create the object;
				 * also used for error reporting. */
    Tcl_ObjectContext context,	/* The object/call context. */
    int objc,			/* Number of arguments. */
    Tcl_Obj *const *objv)	/* The actual arguments. */
{
    Object *oPtr = (Object *) Tcl_ObjectContextObject(context);

    /*
     * Sanity check; should not be possible to invoke this method on a
     * non-class.
     */

    if (oPtr->classPtr == NULL) {
	Tcl_Obj *cmdnameObj = TclOOObjectName(interp, oPtr);

	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		"object \"%s\" is not a class", TclGetString(cmdnameObj)));
	Tcl_SetErrorCode(interp, "TCL", "OO", "INSTANTIATE_NONCLASS", (char *)NULL);
	return TCL_ERROR;
    }

    /*
     * Make the object and return its name.
     */

    return TclNRNewObjectInstance(interp, (Tcl_Class) oPtr->classPtr,
	    NULL, NULL, objc, objv, Tcl_ObjectContextSkippedArgs(context),
	    AddConstructionFinalizer(interp));
}

/*
 * ----------------------------------------------------------------------
 *
 * TclOO_Object_Destroy --
 *
 *	Implementation for oo::object->destroy method.
 *
 * ----------------------------------------------------------------------
 */

int
TclOO_Object_Destroy(
    TCL_UNUSED(ClientData),
    Tcl_Interp *interp,		/* Interpreter in which to create the object;
				 * also used for error reporting. */
    Tcl_ObjectContext context,	/* The object/call context. */
    int objc,			/* Number of arguments. */
    Tcl_Obj *const *objv)	/* The actual arguments. */
{
    Object *oPtr = (Object *) Tcl_ObjectContextObject(context);
    CallContext *contextPtr;

    if (objc != Tcl_ObjectContextSkippedArgs(context)) {
	Tcl_WrongNumArgs(interp, Tcl_ObjectContextSkippedArgs(context), objv,
		NULL);
	return TCL_ERROR;
    }
    if (!(oPtr->flags & DESTRUCTOR_CALLED)) {
	oPtr->flags |= DESTRUCTOR_CALLED;
	contextPtr = TclOOGetCallContext(oPtr, NULL, DESTRUCTOR, NULL, NULL,
		NULL);
	if (contextPtr != NULL) {
	    contextPtr->callPtr->flags |= DESTRUCTOR;
	    contextPtr->skip = 0;
	    TclNRAddCallback(interp, AfterNRDestructor, contextPtr,
		    NULL, NULL, NULL);
	    TclPushTailcallPoint(interp);
	    return TclOOInvokeContext(contextPtr, interp, 0, NULL);
	}
    }
    if (oPtr->command) {
	Tcl_DeleteCommandFromToken(interp, oPtr->command);
    }
    return TCL_OK;
}

static int
AfterNRDestructor(
    ClientData data[],
    Tcl_Interp *interp,
    int result)
{
    CallContext *contextPtr = (CallContext *)data[0];

    if (contextPtr->oPtr->command) {
	Tcl_DeleteCommandFromToken(interp, contextPtr->oPtr->command);
    }
    TclOODeleteContext(contextPtr);
    return result;
}

/*
 * ----------------------------------------------------------------------
 *
 * TclOO_Object_Eval --
 *
 *	Implementation for oo::object->eval method.
 *
 * ----------------------------------------------------------------------
 */

int
TclOO_Object_Eval(
    TCL_UNUSED(ClientData),
    Tcl_Interp *interp,		/* Interpreter in which to create the object;
				 * also used for error reporting. */
    Tcl_ObjectContext context,	/* The object/call context. */
    int objc,			/* Number of arguments. */
    Tcl_Obj *const *objv)	/* The actual arguments. */
{
    CallContext *contextPtr = (CallContext *) context;
    Tcl_Object object = Tcl_ObjectContextObject(context);
    const int skip = Tcl_ObjectContextSkippedArgs(context);
    CallFrame *framePtr, **framePtrPtr = &framePtr;
    Tcl_Obj *scriptPtr;
    CmdFrame *invoker;

    if (objc-1 < skip) {
	Tcl_WrongNumArgs(interp, skip, objv, "arg ?arg ...?");
	return TCL_ERROR;
    }

    /*
     * Make the object's namespace the current namespace and evaluate the
     * command(s).
     */

    (void) TclPushStackFrame(interp, (Tcl_CallFrame **) framePtrPtr,
	    Tcl_GetObjectNamespace(object), 0);
    framePtr->objc = objc;
    framePtr->objv = objv;	/* Reference counts do not need to be
				 * incremented here. */

    if (!(contextPtr->callPtr->flags & PUBLIC_METHOD)) {
	object = NULL;		/* Now just for error mesage printing. */
    }

    /*
     * Work out what script we are actually going to evaluate.
     *
     * When there's more than one argument, we concatenate them together with
     * spaces between, then evaluate the result. Tcl_EvalObjEx will delete the
     * object when it decrements its refcount after eval'ing it.
     */

    if (objc != skip+1) {
	scriptPtr = Tcl_ConcatObj(objc-skip, objv+skip);
	invoker = NULL;
    } else {
	scriptPtr = objv[skip];
	invoker = ((Interp *) interp)->cmdFramePtr;
    }

    /*
     * Evaluate the script now, with FinalizeEval to do the processing after
     * the script completes.
     */

    TclNRAddCallback(interp, FinalizeEval, object, NULL, NULL, NULL);
    return TclNREvalObjEx(interp, scriptPtr, 0, invoker, skip);
}

static int
FinalizeEval(
    ClientData data[],
    Tcl_Interp *interp,
    int result)
{
    if (result == TCL_ERROR) {
	Object *oPtr = (Object *)data[0];
	const char *namePtr;

	if (oPtr) {
	    namePtr = TclGetString(TclOOObjectName(interp, oPtr));
	} else {
	    namePtr = "my";
	}

	Tcl_AppendObjToErrorInfo(interp, Tcl_ObjPrintf(
		"\n    (in \"%s eval\" script line %d)",
		namePtr, Tcl_GetErrorLine(interp)));
    }

    /*
     * Restore the previous "current" namespace.
     */

    TclPopStackFrame(interp);
    return result;
}

/*
 * ----------------------------------------------------------------------
 *
 * TclOO_Object_Unknown --
 *
 *	Default unknown method handler method (defined in oo::object). This
 *	just creates a suitable error message.
 *
 * ----------------------------------------------------------------------
 */

int
TclOO_Object_Unknown(
    TCL_UNUSED(ClientData),
    Tcl_Interp *interp,		/* Interpreter in which to create the object;
				 * also used for error reporting. */
    Tcl_ObjectContext context,	/* The object/call context. */
    int objc,			/* Number of arguments. */
    Tcl_Obj *const *objv)	/* The actual arguments. */
{
    CallContext *contextPtr = (CallContext *) context;
    Object *callerObj = NULL;
    Class *callerCls = NULL;
    Object *oPtr = contextPtr->oPtr;
    const char **methodNames;
    int numMethodNames, i, skip = Tcl_ObjectContextSkippedArgs(context);
    CallFrame *framePtr = ((Interp *) interp)->varFramePtr;
    Tcl_Obj *errorMsg;

    /*
     * If no method name, generate an error asking for a method name. (Only by
     * overriding *this* method can an object handle the absence of a method
     * name without an error).
     */

    if (objc < skip+1) {
	Tcl_WrongNumArgs(interp, skip, objv, "method ?arg ...?");
	return TCL_ERROR;
    }

    /*
     * Determine if the calling context should know about extra private
     * methods, and if so, which.
     */

    if (framePtr->isProcCallFrame & FRAME_IS_METHOD) {
	CallContext *callerContext = (CallContext *)framePtr->clientData;
	Method *mPtr = callerContext->callPtr->chain[
		    callerContext->index].mPtr;

	if (mPtr->declaringObjectPtr) {
	    if (oPtr == mPtr->declaringObjectPtr) {
		callerObj = mPtr->declaringObjectPtr;
	    }
	} else {
	    if (TclOOIsReachable(mPtr->declaringClassPtr, oPtr->selfCls)) {
		callerCls = mPtr->declaringClassPtr;
	    }
	}
    }

    /*
     * Get the list of methods that we want to know about.
     */

    numMethodNames = TclOOGetSortedMethodList(oPtr, callerObj, callerCls,
	    contextPtr->callPtr->flags & PUBLIC_METHOD, &methodNames);

    /*
     * Special message when there are no visible methods at all.
     */

    if (numMethodNames == 0) {
	Tcl_Obj *tmpBuf = TclOOObjectName(interp, oPtr);
	const char *piece;

	if (contextPtr->callPtr->flags & PUBLIC_METHOD) {
	    piece = "visible methods";
	} else {
	    piece = "methods";
	}
	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		"object \"%s\" has no %s", TclGetString(tmpBuf), piece));
	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "METHOD",
		TclGetString(objv[skip]), (char *)NULL);
	return TCL_ERROR;
    }

    errorMsg = Tcl_ObjPrintf("unknown method \"%s\": must be ",
	    TclGetString(objv[skip]));
    for (i=0 ; i<numMethodNames-1 ; i++) {
	if (i) {
	    Tcl_AppendToObj(errorMsg, ", ", -1);
	}
	Tcl_AppendToObj(errorMsg, methodNames[i], -1);
    }
    if (i) {
	Tcl_AppendToObj(errorMsg, " or ", -1);
    }
    Tcl_AppendToObj(errorMsg, methodNames[i], -1);
    ckfree(methodNames);
    Tcl_SetObjResult(interp, errorMsg);
    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "METHOD",
	    TclGetString(objv[skip]), (char *)NULL);
    return TCL_ERROR;
}

/*
 * ----------------------------------------------------------------------
 *
 * TclOO_Object_LinkVar --
 *
 *	Implementation of oo::object->variable method.
 *
 * ----------------------------------------------------------------------
 */

int
TclOO_Object_LinkVar(
    TCL_UNUSED(ClientData),
    Tcl_Interp *interp,		/* Interpreter in which to create the object;
				 * also used for error reporting. */
    Tcl_ObjectContext context,	/* The object/call context. */
    int objc,			/* Number of arguments. */
    Tcl_Obj *const *objv)	/* The actual arguments. */
{
    Interp *iPtr = (Interp *) interp;
    Tcl_Object object = Tcl_ObjectContextObject(context);
    Namespace *savedNsPtr;
    int i;

    if (objc-Tcl_ObjectContextSkippedArgs(context) < 0) {
	Tcl_WrongNumArgs(interp, Tcl_ObjectContextSkippedArgs(context), objv,
		"?varName ...?");
	return TCL_ERROR;
    }

    /*
     * A sanity check. Shouldn't ever happen. (This is all that remains of a
     * more complex check inherited from [global] after we have applied the
     * fix for [Bug 2903811]; note that the fix involved *removing* code.)
     */

    if (iPtr->varFramePtr == NULL) {
	return TCL_OK;
    }

    for (i=Tcl_ObjectContextSkippedArgs(context) ; i<objc ; i++) {
	Var *varPtr, *aryPtr;
	const char *varName = TclGetString(objv[i]);

	/*
	 * The variable name must not contain a '::' since that's illegal in
	 * local names.
	 */

	if (strstr(varName, "::") != NULL) {
	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		    "variable name \"%s\" illegal: must not contain namespace"
		    " separator", varName));
	    Tcl_SetErrorCode(interp, "TCL", "UPVAR", "INVERTED", (char *)NULL);
	    return TCL_ERROR;
	}

	/*
	 * Switch to the object's namespace for the duration of this call.
	 * Like this, the variable is looked up in the namespace of the
	 * object, and not in the namespace of the caller. Otherwise this
	 * would only work if the caller was a method of the object itself,
	 * which might not be true if the method was exported. This is a bit
	 * of a hack, but the simplest way to do this (pushing a stack frame
	 * would be horribly expensive by comparison).
	 */

	savedNsPtr = iPtr->varFramePtr->nsPtr;
	iPtr->varFramePtr->nsPtr = (Namespace *)
		Tcl_GetObjectNamespace(object);
	varPtr = TclObjLookupVar(interp, objv[i], NULL, TCL_NAMESPACE_ONLY,
		"define", 1, 0, &aryPtr);
	iPtr->varFramePtr->nsPtr = savedNsPtr;

	if (varPtr == NULL || aryPtr != NULL) {
	    /*
	     * Variable cannot be an element in an array. If aryPtr is not
	     * NULL, it is an element, so throw up an error and return.
	     */

	    TclVarErrMsg(interp, varName, NULL, "define",
		    "name refers to an element in an array");
	    Tcl_SetErrorCode(interp, "TCL", "UPVAR", "LOCAL_ELEMENT", (char *)NULL);
	    return TCL_ERROR;
	}

	/*
	 * Arrange for the lifetime of the variable to be correctly managed.
	 * This is copied out of Tcl_VariableObjCmd...
	 */

	if (!TclIsVarNamespaceVar(varPtr)) {
	    TclSetVarNamespaceVar(varPtr);
	}

	if (TclPtrMakeUpvar(interp, varPtr, varName, 0, -1) != TCL_OK) {
	    return TCL_ERROR;
	}
    }
    return TCL_OK;
}

/*
 * ----------------------------------------------------------------------
 *
 * TclOO_Object_VarName --
 *
 *	Implementation of the oo::object->varname method.
 *
 * ----------------------------------------------------------------------
 */

int
TclOO_Object_VarName(
    TCL_UNUSED(ClientData),
    Tcl_Interp *interp,		/* Interpreter in which to create the object;
				 * also used for error reporting. */
    Tcl_ObjectContext context,	/* The object/call context. */
    int objc,			/* Number of arguments. */
    Tcl_Obj *const *objv)	/* The actual arguments. */
{
    Var *varPtr, *aryVar;
    Tcl_Obj *varNamePtr, *argPtr;
    CallFrame *framePtr = ((Interp *) interp)->varFramePtr;
    const char *arg;

    if (Tcl_ObjectContextSkippedArgs(context)+1 != objc) {
	Tcl_WrongNumArgs(interp, Tcl_ObjectContextSkippedArgs(context), objv,
		"varName");
	return TCL_ERROR;
    }
    argPtr = objv[objc-1];
    arg = Tcl_GetString(argPtr);

    /*
     * Convert the variable name to fully-qualified form if it wasn't already.
     * This has to be done prior to lookup because we can run into problems
     * with resolvers otherwise. [Bug 3603695]
     *
     * We still need to do the lookup; the variable could be linked to another
     * variable and we want the target's name.
     */

    if (arg[0] == ':' && arg[1] == ':') {
	varNamePtr = argPtr;
    } else {
	Tcl_Namespace *namespacePtr =
		Tcl_GetObjectNamespace(Tcl_ObjectContextObject(context));

	/*
	 * Private method handling. [TIP 500]
	 *
	 * If we're in a context that can see some private methods of an
	 * object, we may need to precede a variable name with its prefix.
	 * This is a little tricky as we need to check through the inheritance
	 * hierarchy when the method was declared by a class to see if the
	 * current object is an instance of that class.
	 */

	if (framePtr->isProcCallFrame & FRAME_IS_METHOD) {
	    Object *oPtr = (Object *) Tcl_ObjectContextObject(context);
	    CallContext *callerContext = (CallContext *)framePtr->clientData;
	    Method *mPtr = callerContext->callPtr->chain[
		    callerContext->index].mPtr;
	    PrivateVariableMapping *pvPtr;
	    int i;

	    if (mPtr->declaringObjectPtr == oPtr) {
		FOREACH_STRUCT(pvPtr, oPtr->privateVariables) {
		    if (!strcmp(Tcl_GetString(pvPtr->variableObj),
			    Tcl_GetString(argPtr))) {
			argPtr = pvPtr->fullNameObj;
			break;
		    }
		}
	    } else if (mPtr->declaringClassPtr &&
		    mPtr->declaringClassPtr->privateVariables.num) {
		Class *clsPtr = mPtr->declaringClassPtr;
		int isInstance = TclOOIsReachable(clsPtr, oPtr->selfCls);
		Class *mixinCls;

		if (!isInstance) {
		    FOREACH(mixinCls, oPtr->mixins) {
			if (TclOOIsReachable(clsPtr, mixinCls)) {
			    isInstance = 1;
			    break;
			}
		    }
		}
		if (isInstance) {
		    FOREACH_STRUCT(pvPtr, clsPtr->privateVariables) {
			if (!strcmp(Tcl_GetString(pvPtr->variableObj),
				Tcl_GetString(argPtr))) {
			    argPtr = pvPtr->fullNameObj;
			    break;
			}
		    }
		}
	    }
	}

	varNamePtr = Tcl_NewStringObj(namespacePtr->fullName, -1);
	Tcl_AppendToObj(varNamePtr, "::", 2);
	Tcl_AppendObjToObj(varNamePtr, argPtr);
    }
    Tcl_IncrRefCount(varNamePtr);
    varPtr = TclObjLookupVar(interp, varNamePtr, NULL,
	    TCL_NAMESPACE_ONLY|TCL_LEAVE_ERR_MSG, "refer to", 1, 1, &aryVar);
    Tcl_DecrRefCount(varNamePtr);
    if (varPtr == NULL) {
	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARIABLE", arg, (char *)NULL);
	return TCL_ERROR;
    }

    /*
     * Now that we've pinned down what variable we're really talking about
     * (including traversing variable links), convert back to a name.
     */

    TclNewObj(varNamePtr);
    if (aryVar != NULL) {
	Tcl_GetVariableFullName(interp, (Tcl_Var) aryVar, varNamePtr);

	/*
	 * WARNING! This code pokes inside the implementation of hash tables!
	 */

	Tcl_AppendToObj(varNamePtr, "(", -1);
	Tcl_AppendObjToObj(varNamePtr, ((VarInHash *)
		varPtr)->entry.key.objPtr);
	Tcl_AppendToObj(varNamePtr, ")", -1);
    } else {
	Tcl_GetVariableFullName(interp, (Tcl_Var) varPtr, varNamePtr);
    }
    Tcl_SetObjResult(interp, varNamePtr);
    return TCL_OK;
}

/*
 * ----------------------------------------------------------------------
 *
 * TclOONextObjCmd, TclOONextToObjCmd --
 *
 *	Implementation of the [next] and [nextto] commands. Note that these
 *	commands are only ever to be used inside the body of a procedure-like
 *	method.
 *
 * ----------------------------------------------------------------------
 */

int
TclOONextObjCmd(
    TCL_UNUSED(ClientData),
    Tcl_Interp *interp,
    int objc,
    Tcl_Obj *const *objv)
{
    Interp *iPtr = (Interp *) interp;
    CallFrame *framePtr = iPtr->varFramePtr;
    Tcl_ObjectContext context;

    /*
     * Start with sanity checks on the calling context to make sure that we
     * are invoked from a suitable method context. If so, we can safely
     * retrieve the handle to the object call context.
     */

    if (framePtr == NULL || !(framePtr->isProcCallFrame & FRAME_IS_METHOD)) {
	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		"%s may only be called from inside a method",
		TclGetString(objv[0])));
	Tcl_SetErrorCode(interp, "TCL", "OO", "CONTEXT_REQUIRED", (char *)NULL);
	return TCL_ERROR;
    }
    context = (Tcl_ObjectContext)framePtr->clientData;

    /*
     * Invoke the (advanced) method call context in the caller context. Note
     * that this is like [uplevel 1] and not [eval].
     */

    TclNRAddCallback(interp, NextRestoreFrame, framePtr, NULL,NULL,NULL);
    iPtr->varFramePtr = framePtr->callerVarPtr;
    return TclNRObjectContextInvokeNext(interp, context, objc, objv, 1);
}

int
TclOONextToObjCmd(
    TCL_UNUSED(ClientData),
    Tcl_Interp *interp,
    int objc,
    Tcl_Obj *const *objv)
{
    Interp *iPtr = (Interp *) interp;
    CallFrame *framePtr = iPtr->varFramePtr;
    Class *classPtr;
    CallContext *contextPtr;
    int i;
    Tcl_Object object;
    const char *methodType;

    /*
     * Start with sanity checks on the calling context to make sure that we
     * are invoked from a suitable method context. If so, we can safely
     * retrieve the handle to the object call context.
     */

    if (framePtr == NULL || !(framePtr->isProcCallFrame & FRAME_IS_METHOD)) {
	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		"%s may only be called from inside a method",
		TclGetString(objv[0])));
	Tcl_SetErrorCode(interp, "TCL", "OO", "CONTEXT_REQUIRED", (char *)NULL);
	return TCL_ERROR;
    }
    contextPtr = (CallContext *)framePtr->clientData;

    /*
     * Sanity check the arguments; we need the first one to refer to a class.
     */

    if (objc < 2) {
	Tcl_WrongNumArgs(interp, 1, objv, "class ?arg...?");
	return TCL_ERROR;
    }
    object = Tcl_GetObjectFromObj(interp, objv[1]);
    if (object == NULL) {
	return TCL_ERROR;
    }
    classPtr = ((Object *)object)->classPtr;
    if (classPtr == NULL) {
	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		"\"%s\" is not a class", TclGetString(objv[1])));
	Tcl_SetErrorCode(interp, "TCL", "OO", "CLASS_REQUIRED", (char *)NULL);
	return TCL_ERROR;
    }

    /*
     * Search for an implementation of a method associated with the current
     * call on the call chain past the point where we currently are. Do not
     * allow jumping backwards!
     */

    for (i=contextPtr->index+1 ; i<contextPtr->callPtr->numChain ; i++) {
	struct MInvoke *miPtr = contextPtr->callPtr->chain + i;

	if (!miPtr->isFilter && miPtr->mPtr->declaringClassPtr == classPtr) {
	    /*
	     * Invoke the (advanced) method call context in the caller
	     * context. Note that this is like [uplevel 1] and not [eval].
	     */

	    TclNRAddCallback(interp, NextRestoreFrame, framePtr,
		    contextPtr, INT2PTR(contextPtr->index), NULL);
	    contextPtr->index = i-1;
	    iPtr->varFramePtr = framePtr->callerVarPtr;
	    return TclNRObjectContextInvokeNext(interp,
		    (Tcl_ObjectContext) contextPtr, objc, objv, 2);
	}
    }

    /*
     * Generate an appropriate error message, depending on whether the value
     * is on the chain but unreachable, or not on the chain at all.
     */

    if (contextPtr->callPtr->flags & CONSTRUCTOR) {
	methodType = "constructor";
    } else if (contextPtr->callPtr->flags & DESTRUCTOR) {
	methodType = "destructor";
    } else {
	methodType = "method";
    }

    for (i=contextPtr->index ; i>=0 ; i--) {
	struct MInvoke *miPtr = contextPtr->callPtr->chain + i;

	if (!miPtr->isFilter && miPtr->mPtr->declaringClassPtr == classPtr) {
	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		    "%s implementation by \"%s\" not reachable from here",
		    methodType, TclGetString(objv[1])));
	    Tcl_SetErrorCode(interp, "TCL", "OO", "CLASS_NOT_REACHABLE",
		    (char *)NULL);
	    return TCL_ERROR;
	}
    }
    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
	    "%s has no non-filter implementation by \"%s\"",
	    methodType, TclGetString(objv[1])));
    Tcl_SetErrorCode(interp, "TCL", "OO", "CLASS_NOT_THERE", (char *)NULL);
    return TCL_ERROR;
}

static int
NextRestoreFrame(
    ClientData data[],
    Tcl_Interp *interp,
    int result)
{
    Interp *iPtr = (Interp *) interp;
    CallContext *contextPtr = (CallContext *)data[1];

    iPtr->varFramePtr = (CallFrame *)data[0];
    if (contextPtr != NULL) {
	contextPtr->index = PTR2INT(data[2]);
    }
    return result;
}

/*
 * ----------------------------------------------------------------------
 *
 * TclOOSelfObjCmd --
 *
 *	Implementation of the [self] command, which provides introspection of
 *	the call context.
 *
 * ----------------------------------------------------------------------
 */

int
TclOOSelfObjCmd(
    TCL_UNUSED(ClientData),
    Tcl_Interp *interp,
    int objc,
    Tcl_Obj *const *objv)
{
    static const char *const subcmds[] = {
	"call", "caller", "class", "filter", "method", "namespace", "next",
	"object", "target", NULL
    };
    enum SelfCmds {
	SELF_CALL, SELF_CALLER, SELF_CLASS, SELF_FILTER, SELF_METHOD, SELF_NS,
	SELF_NEXT, SELF_OBJECT, SELF_TARGET
    };
    Interp *iPtr = (Interp *) interp;
    CallFrame *framePtr = iPtr->varFramePtr;
    CallContext *contextPtr;
    Tcl_Obj *result[3];
    int index;

#define CurrentlyInvoked(contextPtr) \
    ((contextPtr)->callPtr->chain[(contextPtr)->index])

    /*
     * Start with sanity checks on the calling context and the method context.
     */

    if (framePtr == NULL || !(framePtr->isProcCallFrame & FRAME_IS_METHOD)) {
	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		"%s may only be called from inside a method",
		TclGetString(objv[0])));
	Tcl_SetErrorCode(interp, "TCL", "OO", "CONTEXT_REQUIRED", (char *)NULL);
	return TCL_ERROR;
    }

    contextPtr = (CallContext*)framePtr->clientData;

    /*
     * Now we do "conventional" argument parsing for a while. Note that no
     * subcommand takes arguments.
     */

    if (objc > 2) {
	Tcl_WrongNumArgs(interp, 1, objv, "subcommand");
	return TCL_ERROR;
    } else if (objc == 1) {
	index = SELF_OBJECT;
    } else if (Tcl_GetIndexFromObj(interp, objv[1], subcmds, "subcommand", 0,
	    &index) != TCL_OK) {
	return TCL_ERROR;
    }

    switch ((enum SelfCmds) index) {
    case SELF_OBJECT:
	Tcl_SetObjResult(interp, TclOOObjectName(interp, contextPtr->oPtr));
	return TCL_OK;
    case SELF_NS:
	Tcl_SetObjResult(interp, Tcl_NewStringObj(
		contextPtr->oPtr->namespacePtr->fullName,-1));
	return TCL_OK;
    case SELF_CLASS: {
	Class *clsPtr = CurrentlyInvoked(contextPtr).mPtr->declaringClassPtr;

	if (clsPtr == NULL) {
	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
		    "method not defined by a class", -1));
	    Tcl_SetErrorCode(interp, "TCL", "OO", "UNMATCHED_CONTEXT", (char *)NULL);
	    return TCL_ERROR;
	}

	Tcl_SetObjResult(interp, TclOOObjectName(interp, clsPtr->thisPtr));
	return TCL_OK;
    }
    case SELF_METHOD:
	if (contextPtr->callPtr->flags & CONSTRUCTOR) {
	    Tcl_SetObjResult(interp, contextPtr->oPtr->fPtr->constructorName);
	} else if (contextPtr->callPtr->flags & DESTRUCTOR) {
	    Tcl_SetObjResult(interp, contextPtr->oPtr->fPtr->destructorName);
	} else {
	    Tcl_SetObjResult(interp,
		    CurrentlyInvoked(contextPtr).mPtr->namePtr);
	}
	return TCL_OK;
    case SELF_FILTER:
	if (!CurrentlyInvoked(contextPtr).isFilter) {
	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
		    "not inside a filtering context", -1));
	    Tcl_SetErrorCode(interp, "TCL", "OO", "UNMATCHED_CONTEXT", (char *)NULL);
	    return TCL_ERROR;
	} else {
	    struct MInvoke *miPtr = &CurrentlyInvoked(contextPtr);
	    Object *oPtr;
	    const char *type;

	    if (miPtr->filterDeclarer != NULL) {
		oPtr = miPtr->filterDeclarer->thisPtr;
		type = "class";
	    } else {
		oPtr = contextPtr->oPtr;
		type = "object";
	    }

	    result[0] = TclOOObjectName(interp, oPtr);
	    result[1] = Tcl_NewStringObj(type, -1);
	    result[2] = miPtr->mPtr->namePtr;
	    Tcl_SetObjResult(interp, Tcl_NewListObj(3, result));
	    return TCL_OK;
	}
    case SELF_CALLER:
	if ((framePtr->callerVarPtr == NULL) ||
		!(framePtr->callerVarPtr->isProcCallFrame & FRAME_IS_METHOD)){
	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
		    "caller is not an object", -1));
	    Tcl_SetErrorCode(interp, "TCL", "OO", "CONTEXT_REQUIRED", (char *)NULL);
	    return TCL_ERROR;
	} else {
	    CallContext *callerPtr = (CallContext *)framePtr->callerVarPtr->clientData;
	    Method *mPtr = callerPtr->callPtr->chain[callerPtr->index].mPtr;
	    Object *declarerPtr;

	    if (mPtr->declaringClassPtr != NULL) {
		declarerPtr = mPtr->declaringClassPtr->thisPtr;
	    } else if (mPtr->declaringObjectPtr != NULL) {
		declarerPtr = mPtr->declaringObjectPtr;
	    } else {
		/*
		 * This should be unreachable code.
		 */

		Tcl_SetObjResult(interp, Tcl_NewStringObj(
			"method without declarer!", -1));
		return TCL_ERROR;
	    }

	    result[0] = TclOOObjectName(interp, declarerPtr);
	    result[1] = TclOOObjectName(interp, callerPtr->oPtr);
	    if (callerPtr->callPtr->flags & CONSTRUCTOR) {
		result[2] = declarerPtr->fPtr->constructorName;
	    } else if (callerPtr->callPtr->flags & DESTRUCTOR) {
		result[2] = declarerPtr->fPtr->destructorName;
	    } else {
		result[2] = mPtr->namePtr;
	    }
	    Tcl_SetObjResult(interp, Tcl_NewListObj(3, result));
	    return TCL_OK;
	}
    case SELF_NEXT:
	if (contextPtr->index < contextPtr->callPtr->numChain-1) {
	    Method *mPtr =
		    contextPtr->callPtr->chain[contextPtr->index+1].mPtr;
	    Object *declarerPtr;

	    if (mPtr->declaringClassPtr != NULL) {
		declarerPtr = mPtr->declaringClassPtr->thisPtr;
	    } else if (mPtr->declaringObjectPtr != NULL) {
		declarerPtr = mPtr->declaringObjectPtr;
	    } else {
		/*
		 * This should be unreachable code.
		 */

		Tcl_SetObjResult(interp, Tcl_NewStringObj(
			"method without declarer!", -1));
		return TCL_ERROR;
	    }

	    result[0] = TclOOObjectName(interp, declarerPtr);
	    if (contextPtr->callPtr->flags & CONSTRUCTOR) {
		result[1] = declarerPtr->fPtr->constructorName;
	    } else if (contextPtr->callPtr->flags & DESTRUCTOR) {
		result[1] = declarerPtr->fPtr->destructorName;
	    } else {
		result[1] = mPtr->namePtr;
	    }
	    Tcl_SetObjResult(interp, Tcl_NewListObj(2, result));
	}
	return TCL_OK;
    case SELF_TARGET:
	if (!CurrentlyInvoked(contextPtr).isFilter) {
	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
		    "not inside a filtering context", -1));
	    Tcl_SetErrorCode(interp, "TCL", "OO", "UNMATCHED_CONTEXT", (char *)NULL);
	    return TCL_ERROR;
	} else {
	    Method *mPtr;
	    Object *declarerPtr;
	    int i;

	    for (i=contextPtr->index ; i<contextPtr->callPtr->numChain ; i++){
		if (!contextPtr->callPtr->chain[i].isFilter) {
		    break;
		}
	    }
	    if (i == contextPtr->callPtr->numChain) {
		Tcl_Panic("filtering call chain without terminal non-filter");
	    }
	    mPtr = contextPtr->callPtr->chain[i].mPtr;
	    if (mPtr->declaringClassPtr != NULL) {
		declarerPtr = mPtr->declaringClassPtr->thisPtr;
	    } else if (mPtr->declaringObjectPtr != NULL) {
		declarerPtr = mPtr->declaringObjectPtr;
	    } else {
		/*
		 * This should be unreachable code.
		 */

		Tcl_SetObjResult(interp, Tcl_NewStringObj(
			"method without declarer!", -1));
		return TCL_ERROR;
	    }
	    result[0] = TclOOObjectName(interp, declarerPtr);
	    result[1] = mPtr->namePtr;
	    Tcl_SetObjResult(interp, Tcl_NewListObj(2, result));
	    return TCL_OK;
	}
    case SELF_CALL:
	result[0] = TclOORenderCallChain(interp, contextPtr->callPtr);
	TclNewIndexObj(result[1], contextPtr->index);
	Tcl_SetObjResult(interp, Tcl_NewListObj(2, result));
	return TCL_OK;
    }
    return TCL_ERROR;
}

/*
 * ----------------------------------------------------------------------
 *
 * CopyObjectCmd --
 *
 *	Implementation of the [oo::copy] command, which clones an object (but
 *	not its namespace). Note that no constructors are called during this
 *	process.
 *
 * ----------------------------------------------------------------------
 */

int
TclOOCopyObjectCmd(
    TCL_UNUSED(ClientData),
    Tcl_Interp *interp,
    int objc,
    Tcl_Obj *const *objv)
{
    Tcl_Object oPtr, o2Ptr;

    if (objc < 2 || objc > 4) {
	Tcl_WrongNumArgs(interp, 1, objv,
			 "sourceName ?targetName? ?targetNamespace?");
	return TCL_ERROR;
    }

    oPtr = Tcl_GetObjectFromObj(interp, objv[1]);
    if (oPtr == NULL) {
	return TCL_ERROR;
    }

    /*
     * Create a cloned object of the correct class. Note that constructors are
     * not called. Also note that we must resolve the object name ourselves
     * because we do not want to create the object in the current namespace,
     * but rather in the context of the namespace of the caller of the overall
     * [oo::define] command.
     */

    if (objc == 2) {
	o2Ptr = Tcl_CopyObjectInstance(interp, oPtr, NULL, NULL);
    } else {
	const char *name, *namespaceName;

	name = TclGetString(objv[2]);
	if (name[0] == '\0') {
	    name = NULL;
	}

	/*
	 * Choose a unique namespace name if the user didn't supply one.
	 */

	namespaceName = NULL;
	if (objc == 4) {
	    namespaceName = TclGetString(objv[3]);

	    if (namespaceName[0] == '\0') {
		namespaceName = NULL;
	    } else if (Tcl_FindNamespace(interp, namespaceName, NULL,
		    0) != NULL) {
		Tcl_SetObjResult(interp, Tcl_ObjPrintf(
			"%s refers to an existing namespace", namespaceName));
		return TCL_ERROR;
	    }
	}

	o2Ptr = Tcl_CopyObjectInstance(interp, oPtr, name, namespaceName);
    }

    if (o2Ptr == NULL) {
	return TCL_ERROR;
    }

    /*
     * Return the name of the cloned object.
     */

    Tcl_SetObjResult(interp, TclOOObjectName(interp, (Object *) o2Ptr));
    return TCL_OK;
}

/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 4
 * fill-column: 78
 * End:
 */