.BE
.SH DESCRIPTION
.PP
Append all of the \fIvalue\fR arguments to the current value
of variable \fIvarName\fR.  If \fIvarName\fR does not exist,
it is given a value equal to the concatenation of all the
\fIvalue\fR arguments.
.VS TIP508
If \fIvarName\fR indicate an element that does not exist of an array that has
a default value set, the concatenation of the default value and all the
\fIvalue\fR arguments will be stored in the array element.
.VE TIP508
The result of this command is the new value stored in variable
\fIvarName\fR.
This command provides an efficient way to build up long
variables incrementally.
For example,
.QW "\fBappend a $b\fR"
is much more efficient than

puts $var
# Prints 0,1,2,3,4,5,6,7,8,9,10
.CE
.SH "SEE ALSO"
concat(n), lappend(n)
.SH KEYWORDS
append, variable
'\" Local Variables:
'\" mode: nroff
'\" End:
.\" Local variables:
.\" mode: nroff
.\" fill-column: 78
.\" End:

'\"
'\" Copyright (c) 1993-1994 The Regents of the University of California.
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
.TH array n 8.3 Tcl "Tcl Built-In Commands"
.TH array n 8.7 Tcl "Tcl Built-In Commands"
.so man.macros
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
array \- Manipulate array variables
.SH SYNOPSIS
\fBarray \fIoption arrayName\fR ?\fIarg arg ...\fR?

\fISearchId\fR indicates which search on \fIarrayName\fR to
check, and must have been the return value from a previous
invocation of \fBarray startsearch\fR.
This option is particularly useful if an array has an element
with an empty name, since the return value from
\fBarray nextelement\fR will not indicate whether the search
has been completed.
.TP
\fBarray default \fIsubcommand arrayName args...\fR
.VS TIP508
Manages the default value of the array. Arrays initially have no default
value, but this command allows you to set one; the default value will be
returned when reading from an element of the array \farrayName\fR if the read
would otherwise result in an error. Note that this may cause the \fBappend\fR,
\fBdict\fR, \fBincr\fR and \fBlappend\fR commands to change their behavior in
relation to non-existing array elements.
.RS
.PP
The \fIsubcommand\fR argument controls what exact operation will be performed
on the default value of \fIarrayName\fR. Supported \fIsubcommand\fRs are:
.VE TIP508
.TP
\fBarray default exists \fIarrayName\fR
.VS TIP508
This returns a boolean value indicating whether a default value has been set
for the array \fIarrayName\fR. Returns a false value if \fIarrayName\fR does
not exist. Raises an error if \fIarrayName\fR is an existing variable that is
not an array.
.VE TIP508
.TP
\fBarray default get \fIarrayName\fR
.VS TIP508
This returns the current default value for the array \fIarrayName\fR.  Raises
an error if \fIarrayName\fR is an existing variable that is not an array, or
if \fIarrayName\fR is an array without a default value.
.VE TIP508
.TP
\fBarray default set \fIarrayName value\fR
.VS TIP508
This sets the default value for the array \fIarrayName\fR to \fIvalue\fR.
Returns the empty string. Raises an error if \fIarrayName\fR is an existing
variable that is not an array, or if \fIarrayName\fR is an illegal name for an
array. If \fIarrayName\fR does not currently exist, it is created as an empty
array as well as having its default value set.
.VE TIP508
.TP
\fBarray default unset \fIarrayName\fR
.VS TIP508
This removes the default value for the array \fIarrayName\fR and returns the
empty string. Does nothing if \fIarrayName\fR does not have a default
value. Raises an error if \fIarrayName\fR is an existing variable that is not
an array.
.VE TIP508
.RE
.TP
\fBarray donesearch \fIarrayName searchId\fR
This command terminates an array search and destroys all the
state associated with that search.  \fISearchId\fR indicates
which search on \fIarrayName\fR to destroy, and must have
been the return value from a previous invocation of
\fBarray startsearch\fR.  Returns an empty string.

    number of buckets with 10 or more entries: 0
    average search distance for entry: 1.2
.CE
.SH "SEE ALSO"
list(n), string(n), variable(n), trace(n), foreach(n)
.SH KEYWORDS
array, element names, search
.\" Local variables:
.\" mode: nroff
.\" fill-column: 78
.\" End:

\fBdict append \fIdictionaryVariable key \fR?\fIstring ...\fR?
.
This appends the given string (or strings) to the value that the given
key maps to in the dictionary value contained in the given variable,
writing the resulting dictionary value back to that variable.
Non-existent keys are treated as if they map to an empty string. The
updated dictionary value is returned.
.VS TIP508
If \fIdictionaryVarable\fR indicates an element that does not exist of an
array that has a default value set, the default value and will be used as the
value of the dictionary prior to the appending operation.
.VE TIP508
.TP
\fBdict create \fR?\fIkey value ...\fR?
.
Return a new dictionary that contains each of the key/value mappings
listed as arguments (keys and values alternating, with each key being
followed by its associated value.)
.TP

This adds the given increment value (an integer that defaults to 1 if
not specified) to the value that the given key maps to in the
dictionary value contained in the given variable, writing the
resulting dictionary value back to that variable. Non-existent keys
are treated as if they map to 0. It is an error to increment a value
for an existing key if that value is not an integer. The updated
dictionary value is returned.
.VS TIP508
If \fIdictionaryVarable\fR indicates an element that does not exist of an
array that has a default value set, the default value and will be used as the
value of the dictionary prior to the incrementing operation.
.VE TIP508
.TP
\fBdict info \fIdictionaryValue\fR
.
This returns information (intended for display to people) about the
given dictionary though the format of this data is dependent on the
implementation of the dictionary. For dictionaries that are
implemented by hash tables, it is expected that this will return the

This appends the given items to the list value that the given key maps
to in the dictionary value contained in the given variable, writing
the resulting dictionary value back to that variable. Non-existent
keys are treated as if they map to an empty list, and it is legal for
there to be no items to append to the list. It is an error for the
value that the key maps to to not be representable as a list. The
updated dictionary value is returned.
.VS TIP508
If \fIdictionaryVarable\fR indicates an element that does not exist of an
array that has a default value set, the default value and will be used as the
value of the dictionary prior to the list-appending operation.
.VE TIP508
.TP
\fBdict map \fR{\fIkeyVariable valueVariable\fR} \fIdictionaryValue body\fR
.
This command applies a transformation to each element of a dictionary,
returning a new dictionary. It takes three arguments: the first is a
two-element list of variable names (for the key and value respectively of each
mapping in the dictionary), the second the dictionary value to iterate across,

\fBdict set \fIdictionaryVariable key \fR?\fIkey ...\fR? \fIvalue\fR
.
This operation takes the name of a variable containing a dictionary
value and places an updated dictionary value in that variable
containing a mapping from the given key to the given value. When
multiple keys are present, this operation creates or updates a chain
of nested dictionaries. The updated dictionary value is returned.
.VS TIP508
If \fIdictionaryVarable\fR indicates an element that does not exist of an
array that has a default value set, the default value and will be used as the
value of the dictionary prior to the value insert/update operation.
.VE TIP508
.TP
\fBdict size \fIdictionaryValue\fR
.
Return the number of key/value mappings in the given dictionary value.
.TP
\fBdict unset \fIdictionaryVariable key \fR?\fIkey ...\fR?
.
This operation (the companion to \fBdict set\fR) takes the name of a
variable containing a dictionary value and places an updated
dictionary value in that variable that does not contain a mapping for
the given key. Where multiple keys are present, this describes a path
through nested dictionaries to the mapping to remove. At least one key
must be specified, but the last key on the key-path need not exist.
All other components on the path must exist. The updated dictionary
value is returned.
.VS TIP508
If \fIdictionaryVarable\fR indicates an element that does not exist of an
array that has a default value set, the default value and will be used as the
value of the dictionary prior to the value remove operation.
.VE TIP508
.TP
\fBdict update \fIdictionaryVariable key varName \fR?\fIkey varName ...\fR? \fIbody\fR
.
Execute the Tcl script in \fIbody\fR with the value for each \fIkey\fR
(as found by reading the dictionary value in \fIdictionaryVariable\fR)
mapped to the variable \fIvarName\fR. There may be multiple
\fIkey\fR/\fIvarName\fR pairs. If a \fIkey\fR does not have a mapping,
that corresponds to an unset \fIvarName\fR. When \fIbody\fR
terminates, any changes made to the \fIvarName\fRs is reflected back
to the dictionary within \fIdictionaryVariable\fR (unless
\fIdictionaryVariable\fR itself becomes unreadable, when all updates
are silently discarded), even if the result of \fIbody\fR is an error
or some other kind of exceptional exit. The result of \fBdict
update\fR is (unless some kind of error occurs) the result of the
evaluation of \fIbody\fR.
.VS TIP508
If \fIdictionaryVarable\fR indicates an element that does not exist of an
array that has a default value set, the default value and will be used as the
value of the dictionary prior to the update operation.
.VE TIP508
.RS
.PP
Each \fIvarName\fR is mapped in the scope enclosing the \fBdict update\fR;
it is recommended that this command only be used in a local scope
(\fBproc\fRedure, lambda term for \fBapply\fR, or method). Because of
this, the variables set by \fBdict update\fR will continue to
exist after the command finishes (unless explicitly \fBunset\fR).

for the execution of \fIbody\fR. As with \fBdict update\fR, making
\fIdictionaryVariable\fR unreadable will make the updates to the
dictionary be discarded, and this also happens if the contents of
\fIdictionaryVariable\fR are adjusted so that the chain of
dictionaries no longer exists. The result of \fBdict with\fR is
(unless some kind of error occurs) the result of the evaluation of
\fIbody\fR.
.VS TIP508
If \fIdictionaryVarable\fR indicates an element that does not exist of an
array that has a default value set, the default value and will be used as the
value of the dictionary prior to the updating operation.
.VE TIP508
.RS
.PP
The variables are mapped in the scope enclosing the \fBdict with\fR;
it is recommended that this command only be used in a local scope
(\fBproc\fRedure, lambda term for \fBapply\fR, or method). Because of
this, the variables set by \fBdict with\fR will continue to
exist after the command finishes (unless explicitly \fBunset\fR).

1 is added to \fIvarName\fR.
The new value is stored as a decimal string in variable \fIvarName\fR
and also returned as result.
.PP
Starting with the Tcl 8.5 release, the variable \fIvarName\fR passed
to \fBincr\fR may be unset, and in that case, it will be set to
the value \fIincrement\fR or to the default increment value of \fB1\fR.
.VS TIP508
If \fIvarName\fR indicate an element that does not exist of an array that has
a default value set, the sum of the default value and the \fIincrement\fR (or
1) will be stored in the array element.
.VE TIP508
.SH EXAMPLES
.PP
Add one to the contents of the variable \fIx\fR:
.PP
.CS
\fBincr\fR x
.CE

.CS
\fBincr\fR x 0
.CE
.SH "SEE ALSO"
expr(n), set(n)
.SH KEYWORDS
add, increment, variable, value
.\" Local variables:
.\" mode: nroff
.\" fill-column: 78
.\" End:

.SH DESCRIPTION
.PP
This command treats the variable given by \fIvarName\fR as a list
and appends each of the \fIvalue\fR arguments to that list as a separate
element, with spaces between elements.
If \fIvarName\fR does not exist, it is created as a list with elements
given by the \fIvalue\fR arguments.
.VS TIP508
If \fIvarName\fR indicate an element that does not exist of an array that has
a default value set, list that is comprised of the default value with all the
\fIvalue\fR arguments appended as elements will be stored in the array
element.
.VE TIP508
\fBLappend\fR is similar to \fBappend\fR except that the \fIvalue\fRs
are appended as list elements rather than raw text.
This command provides a relatively efficient way to build up
large lists.  For example,
.QW "\fBlappend a $b\fR"
is much more efficient than
.QW "\fBset a [concat $a [list $b]]\fR"

1 2 3 4 5
.CE
.SH "SEE ALSO"
list(n), lindex(n), linsert(n), llength(n), lset(n),
lsort(n), lrange(n)
.SH KEYWORDS
append, element, list, variable
.\" Local variables:
.\" mode: nroff
.\" fill-column: 78
.\" End:

			"variable isn't array", opnd);
		DECACHE_STACK_INFO();
		Tcl_SetErrorCode(interp, "TCL", "WRITE", "ARRAY", NULL);
		CACHE_STACK_INFO();
		TRACE_ERROR(interp);
		goto gotError;
	    }
	    TclSetVarArray(varPtr);
	    TclInitArrayVar(varPtr);
	    varPtr->value.tablePtr = ckalloc(sizeof(TclVarHashTable));
	    TclInitVarHashTable(varPtr->value.tablePtr,
		    TclGetVarNsPtr(varPtr));
#ifdef TCL_COMPILE_DEBUG
	    TRACE_APPEND(("done\n"));
	} else {
	    TRACE_APPEND(("nothing to do\n"));
#endif
	}
	NEXT_INST_V(pcAdjustment, cleanup, 0);

MODULE_SCOPE Tcl_Command TclInitProcessCmd(Tcl_Interp *interp);
MODULE_SCOPE void	TclProcessCreated(Tcl_Pid pid);
MODULE_SCOPE TclProcessWaitStatus TclProcessWait(Tcl_Pid pid, int options,
			    int *codePtr, Tcl_Obj **msgObjPtr,
			    Tcl_Obj **errorObjPtr);

/*
 * TIP #508: [array default]
 */

MODULE_SCOPE void	TclInitArrayVar(Var *arrayPtr);

/*
 * Utility routines for encoding index values as integers. Used by both
 * some of the command compilers and by [lsort] and [lsearch].
 */

MODULE_SCOPE int	TclIndexEncode(Tcl_Interp *interp, Tcl_Obj *objPtr,
			    int before, int after, int *indexPtr);

			    Tcl_Obj *myNamePtr, int myFlags, int index);
static ArraySearch *	ParseSearchId(Tcl_Interp *interp, const Var *varPtr,
			    Tcl_Obj *varNamePtr, Tcl_Obj *handleObj);
static void		UnsetVarStruct(Var *varPtr, Var *arrayPtr,
			    Interp *iPtr, Tcl_Obj *part1Ptr,
			    Tcl_Obj *part2Ptr, int flags, int index);

/*
 * TIP #508: [array default]
 */

static int		ArrayDefaultCmd(ClientData clientData,
			    Tcl_Interp *interp, int objc,
			    Tcl_Obj *const objv[]);
static void		DeleteArrayVar(Var *arrayPtr);
static Tcl_Obj *	GetArrayDefault(Var *arrayPtr);
static void		SetArrayDefault(Var *arrayPtr, Tcl_Obj *defaultObj);

/*
 * Functions defined in this file that may be exported in the future for use
 * by the bytecode compiler and engine or to the public interface.
 */

MODULE_SCOPE Var *	TclLookupSimpleVar(Tcl_Interp *interp,
			    Tcl_Obj *varNamePtr, int flags, const int create,

				 * element, if it doesn't already exist. If 0,
				 * return error if it doesn't exist. */
    Var *arrayPtr,		/* Pointer to the array's Var structure. */
    int index)			/* If >=0, the index of the local array. */
{
    int isNew;
    Var *varPtr;
    TclVarHashTable *tablePtr;
    Namespace *nsPtr;

    /*
     * We're dealing with an array element. Make sure the variable is an array
     * and look up the element (create the element if desired).
     */

    if (TclIsVarUndefined(arrayPtr) && !TclIsVarArrayElement(arrayPtr)) {

			danglingVar, index);
		Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARNAME",
			arrayNamePtr?TclGetString(arrayNamePtr):NULL, NULL);
	    }
	    return NULL;
	}

	TclSetVarArray(arrayPtr);
	TclInitArrayVar(arrayPtr);
	tablePtr = ckalloc(sizeof(TclVarHashTable));
	arrayPtr->value.tablePtr = tablePtr;

	if (TclIsVarInHash(arrayPtr) && TclGetVarNsPtr(arrayPtr)) {
	    nsPtr = TclGetVarNsPtr(arrayPtr);
	} else {
	    nsPtr = NULL;
	}
	TclInitVarHashTable(arrayPtr->value.tablePtr, nsPtr);
    } else if (!TclIsVarArray(arrayPtr)) {
	if (flags & TCL_LEAVE_ERR_MSG) {
	    TclObjVarErrMsg(interp, arrayNamePtr, elNamePtr, msg, needArray,
		    index);
	    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARNAME",
		    arrayNamePtr?TclGetString(arrayNamePtr):NULL, NULL);
	}

    /*
     * Return the element if it's an existing scalar variable.
     */

    if (TclIsVarScalar(varPtr) && !TclIsVarUndefined(varPtr)) {
	return varPtr->value.objPtr;
    }

    /*
     * Return the array default value if any.
     */
    if (arrayPtr && TclIsVarArray(arrayPtr) && GetArrayDefault(arrayPtr)) {
	return GetArrayDefault(arrayPtr);
    }

    if (flags & TCL_LEAVE_ERR_MSG) {
	if (TclIsVarUndefined(varPtr) && arrayPtr
		&& !TclIsVarUndefined(arrayPtr)) {
	    msg = noSuchElement;
	} else if (TclIsVarArray(varPtr)) {
	    msg = isArray;

	    TclObjVarErrMsg(interp, arrayNameObj, NULL, "array set",
		    needArray, -1);
	    Tcl_SetErrorCode(interp, "TCL", "WRITE", "ARRAY", NULL);
	    return TCL_ERROR;
	}
    }
    TclSetVarArray(varPtr);
    TclInitArrayVar(varPtr);
    varPtr->value.tablePtr = ckalloc(sizeof(TclVarHashTable));
    TclInitVarHashTable(varPtr->value.tablePtr, TclGetVarNsPtr(varPtr));
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ArraySizeCmd --

	/* ARGSUSED */
Tcl_Command
TclInitArrayCmd(
    Tcl_Interp *interp)		/* Current interpreter. */
{
    static const EnsembleImplMap arrayImplMap[] = {
	{"anymore",	ArrayAnyMoreCmd,	TclCompileBasic2ArgCmd, NULL, NULL, 0},
	{"default",	ArrayDefaultCmd,	TclCompileBasic2Or3ArgCmd, NULL, NULL, 0},
	{"donesearch",	ArrayDoneSearchCmd,	TclCompileBasic2ArgCmd, NULL, NULL, 0},
	{"exists",	ArrayExistsCmd,		TclCompileArrayExistsCmd, NULL, NULL, 0},
	{"for",		ArrayForObjCmd,		TclCompileBasic3ArgCmd, ArrayForNRCmd, NULL, 0},
	{"get",		ArrayGetCmd,		TclCompileBasic1Or2ArgCmd, NULL, NULL, 0},
	{"names",	ArrayNamesCmd,		TclCompileBasic1To3ArgCmd, NULL, NULL, 0},
	{"nextelement",	ArrayNextElementCmd,	TclCompileBasic2ArgCmd, NULL, NULL, 0},
	{"set",		ArraySetCmd,		TclCompileArraySetCmd, NULL, NULL, 0},

	 * variables, some combinations of [upvar] and [variable] may create
	 * such beasts - see [Bug 604239]. This is necessary to avoid leaking
	 * the corresponding Var struct, and is otherwise harmless.
	 */

	TclClearVarNamespaceVar(elPtr);
    }
    VarHashDeleteTable(varPtr->value.tablePtr);
    ckfree(varPtr->value.tablePtr);
    DeleteArrayVar(varPtr);
}

/*
 *----------------------------------------------------------------------
 *
 * TclObjVarErrMsg --
 *

    /*
     * Only compare string representations of the same length.
     */

    return ((l1 == l2) && !memcmp(p1, p2, l1));
}

/*
 * TIP #508: [array default]
 */

/*
 * The following structure extends the regular TclVarHashTable used by array
 * variables to store their optional default value.
 */

typedef struct ArrayVarHashTable {
    TclVarHashTable table;
    Tcl_Obj *defaultObj;
} ArrayVarHashTable;

/*----------------------------------------------------------------------
 *
 * ArrayDefaultCmd --
 *
 *	This function implements the 'array default' Tcl command. 
 *	Refer to the user documentation for details on what it does.
 *
 * Results:
 *	Returns a standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
static int
ArrayDefaultCmd(
    ClientData clientData,	/* Not used. */
    Tcl_Interp *interp,		/* Current interpreter. */
    int objc,			/* Number of arguments. */
    Tcl_Obj *const objv[])	/* Argument objects. */
{
    static const char *const options[] = {
	"get", "set", "exists", "unset", NULL
    };
    enum options { OPT_GET, OPT_SET, OPT_EXISTS, OPT_UNSET };
    Tcl_Obj *arrayNameObj, *defaultValueObj;
    Var *varPtr, *arrayPtr;
    int isArray, option;

    /*
     * Parse arguments.
     */

    if (objc != 3 && objc != 4) {
	Tcl_WrongNumArgs(interp, 1, objv, "option arrayName ?value?");
	return TCL_ERROR;
    }
    if (Tcl_GetIndexFromObj(interp, objv[1], options, "option",
	    0, &option) != TCL_OK) {
	return TCL_ERROR;
    }

    arrayNameObj = objv[2];

    if (TCL_ERROR == LocateArray(interp, arrayNameObj, &varPtr, &isArray)) {
	return TCL_ERROR;
    }

    switch (option) {
    case OPT_GET:
	if (objc != 3) {
	    Tcl_WrongNumArgs(interp, 2, objv, "arrayName");
	    return TCL_ERROR;
	}
	if (!varPtr || !isArray) {
	    return NotArrayError(interp, arrayNameObj);
	}

	defaultValueObj = GetArrayDefault(varPtr);
	if (!defaultValueObj) {
	    /* Array default must exist. */
	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
		    "array has no default value", -1));
	    Tcl_SetErrorCode(interp, "TCL", "READ", "ARRAY", "DEFAULT", NULL);
	    return TCL_ERROR;
	}
	Tcl_SetObjResult(interp, defaultValueObj);
	return TCL_OK;

    case OPT_SET:
	if (objc != 4) {
	    Tcl_WrongNumArgs(interp, 2, objv, "arrayName value");
	    return TCL_ERROR;
	}

	/*
	 * Attempt to create array if needed.
	 */
	varPtr = TclObjLookupVarEx(interp, arrayNameObj, NULL,
		/*flags*/ TCL_LEAVE_ERR_MSG, /*msg*/ "array default set", 
		/*createPart1*/ 1, /*createPart2*/ 1, &arrayPtr);
	if (varPtr == NULL) {
	    return TCL_ERROR;
	}
	if (arrayPtr) {
	    /*
	     * Not a valid array name.
	     */
	    
	    CleanupVar(varPtr, arrayPtr);
	    TclObjVarErrMsg(interp, arrayNameObj, NULL, "array default set", needArray, -1);
	    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARNAME",
		    TclGetString(arrayNameObj), NULL);
	    return TCL_ERROR;
	}
	if (!TclIsVarArray(varPtr) && !TclIsVarUndefined(varPtr)) {
	    /*
	     * Not an array.
	     */

	    TclObjVarErrMsg(interp, arrayNameObj, NULL, "array default set",
		    needArray, -1);
	    Tcl_SetErrorCode(interp, "TCL", "WRITE", "ARRAY", NULL);
	    return TCL_ERROR;
	}

	if (!TclIsVarArray(varPtr)) {
	    TclInitArrayVar(varPtr);
	}
	defaultValueObj = objv[3];
	SetArrayDefault(varPtr, defaultValueObj);
	return TCL_OK;

    case OPT_EXISTS:
	if (objc != 3) {
	    Tcl_WrongNumArgs(interp, 2, objv, "arrayName");
	    return TCL_ERROR;
	}
	if (varPtr && !isArray) {
	    return NotArrayError(interp, arrayNameObj);
	}

	if (!varPtr) {
	    Tcl_SetObjResult(interp, Tcl_NewBooleanObj(0));
	} else {
	    defaultValueObj = GetArrayDefault(varPtr);
	    Tcl_SetObjResult(interp, Tcl_NewBooleanObj(!!defaultValueObj));
	}
	return TCL_OK;

    case OPT_UNSET:
	if (objc != 3) {
	    Tcl_WrongNumArgs(interp, 2, objv, "arrayName");
	    return TCL_ERROR;
	}
	if (varPtr && !isArray) {
	    return NotArrayError(interp, arrayNameObj);
	}
        
	if (varPtr) {
	    SetArrayDefault(varPtr, NULL);
	}
	return TCL_OK;
    }

    /* Unreached */
    return TCL_ERROR;
}

/*
 * Initialize array variable.
 */

void
TclInitArrayVar(
    Var *arrayPtr)
{
    ArrayVarHashTable *tablePtr;

    TclSetVarArray(arrayPtr);

    tablePtr = ckalloc(sizeof(ArrayVarHashTable));

    // Regular TclVarHashTable initialization.
    arrayPtr->value.tablePtr = (TclVarHashTable *) tablePtr;
    TclInitVarHashTable(arrayPtr->value.tablePtr, TclGetVarNsPtr(arrayPtr));

    // Default value initialization.
    tablePtr->defaultObj = NULL;
}

/*
 * Cleanup array variable.
 */

static void
DeleteArrayVar(
    Var *arrayPtr)
{
    ArrayVarHashTable *tablePtr = (ArrayVarHashTable *) arrayPtr->value.tablePtr;

    // Default value cleanup.
    SetArrayDefault(arrayPtr, NULL);

    // Regular TclVarHashTable cleanup.
    VarHashDeleteTable(arrayPtr->value.tablePtr);

    ckfree(tablePtr);
}

/*
 * Get array default value if any.
 */

static Tcl_Obj *
GetArrayDefault(
    Var *arrayPtr)
{
    ArrayVarHashTable *tablePtr = (ArrayVarHashTable *) arrayPtr->value.tablePtr;
    return tablePtr->defaultObj;
}

/*
 * Set/replace/unset array default value.
 */

static void
SetArrayDefault(
    Var *arrayPtr,
    Tcl_Obj *defaultObj)
{
    ArrayVarHashTable *tablePtr = (ArrayVarHashTable *) arrayPtr->value.tablePtr;
    
    /*
     * Increment/decrement refcount twice to ensure that the object is shared,
     * so that it doesn't get modified accidentally by the folling code:
     * 
     *      array default set v 1
     *      lappend v(a) 2; # returns a new object {1 2}
     *      set v(b); # returns the original default object "1"
     */
    if (tablePtr->defaultObj) {
        Tcl_DecrRefCount(tablePtr->defaultObj);
        Tcl_DecrRefCount(tablePtr->defaultObj);
    }
    tablePtr->defaultObj = defaultObj;
    if (tablePtr->defaultObj) {
        Tcl_IncrRefCount(tablePtr->defaultObj);
        Tcl_IncrRefCount(tablePtr->defaultObj);
    }
}

/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 4
 * fill-column: 78
 * End:
 */