250 lines
10 KiB
Groff
250 lines
10 KiB
Groff
'\"
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'\" Copyright (c) 1989-1993 The Regents of the University of California.
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'\" Copyright (c) 1994-1997 Sun Microsystems, Inc.
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'\"
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'\" See the file "license.terms" for information on usage and redistribution
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'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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'\"
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.TH Tcl_SetVar 3 8.1 Tcl "Tcl Library Procedures"
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.so man.macros
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.BS
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.SH NAME
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Tcl_SetVar2Ex, Tcl_SetVar, Tcl_SetVar2, Tcl_ObjSetVar2, Tcl_GetVar2Ex, Tcl_GetVar, Tcl_GetVar2, Tcl_ObjGetVar2, Tcl_UnsetVar, Tcl_UnsetVar2 \- manipulate Tcl variables
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.SH SYNOPSIS
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.nf
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\fB#include <tcl.h>\fR
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.sp
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Tcl_Obj *
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\fBTcl_SetVar2Ex\fR(\fIinterp, name1, name2, newValuePtr, flags\fR)
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.sp
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const char *
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\fBTcl_SetVar\fR(\fIinterp, varName, newValue, flags\fR)
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.sp
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const char *
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\fBTcl_SetVar2\fR(\fIinterp, name1, name2, newValue, flags\fR)
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.sp
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Tcl_Obj *
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\fBTcl_ObjSetVar2\fR(\fIinterp, part1Ptr, part2Ptr, newValuePtr, flags\fR)
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.sp
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Tcl_Obj *
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\fBTcl_GetVar2Ex\fR(\fIinterp, name1, name2, flags\fR)
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.sp
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const char *
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\fBTcl_GetVar\fR(\fIinterp, varName, flags\fR)
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.sp
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const char *
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\fBTcl_GetVar2\fR(\fIinterp, name1, name2, flags\fR)
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.sp
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Tcl_Obj *
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\fBTcl_ObjGetVar2\fR(\fIinterp, part1Ptr, part2Ptr, flags\fR)
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.sp
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int
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\fBTcl_UnsetVar\fR(\fIinterp, varName, flags\fR)
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.sp
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int
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\fBTcl_UnsetVar2\fR(\fIinterp, name1, name2, flags\fR)
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.SH ARGUMENTS
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.AS Tcl_Interp *newValuePtr
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.AP Tcl_Interp *interp in
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Interpreter containing variable.
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.AP "const char" *name1 in
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Contains the name of an array variable (if \fIname2\fR is non-NULL)
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or (if \fIname2\fR is NULL) either the name of a scalar variable
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or a complete name including both variable name and index.
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May include \fB::\fR namespace qualifiers
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to specify a variable in a particular namespace.
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.AP "const char" *name2 in
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If non-NULL, gives name of element within array; in this
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case \fIname1\fR must refer to an array variable.
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.AP Tcl_Obj *newValuePtr in
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Points to a Tcl value containing the new value for the variable.
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.AP int flags in
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OR-ed combination of bits providing additional information. See below
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for valid values.
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.AP "const char" *varName in
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Name of variable.
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May include \fB::\fR namespace qualifiers
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to specify a variable in a particular namespace.
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May refer to a scalar variable or an element of
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an array.
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.AP "const char" *newValue in
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New value for variable, specified as a null-terminated string.
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A copy of this value is stored in the variable.
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.AP Tcl_Obj *part1Ptr in
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Points to a Tcl value containing the variable's name.
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The name may include a series of \fB::\fR namespace qualifiers
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to specify a variable in a particular namespace.
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May refer to a scalar variable or an element of an array variable.
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.AP Tcl_Obj *part2Ptr in
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If non-NULL, points to a value containing the name of an element
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within an array and \fIpart1Ptr\fR must refer to an array variable.
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.BE
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.SH DESCRIPTION
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.PP
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These procedures are used to create, modify, read, and delete
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Tcl variables from C code.
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.PP
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\fBTcl_SetVar2Ex\fR, \fBTcl_SetVar\fR, \fBTcl_SetVar2\fR, and
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\fBTcl_ObjSetVar2\fR
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will create a new variable or modify an existing one.
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These procedures set the given variable to the value
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given by \fInewValuePtr\fR or \fInewValue\fR and return a
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pointer to the variable's new value, which is stored in Tcl's
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variable structure.
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\fBTcl_SetVar2Ex\fR and \fBTcl_ObjSetVar2\fR take the new value as a
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Tcl_Obj and return
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a pointer to a Tcl_Obj. \fBTcl_SetVar\fR and \fBTcl_SetVar2\fR
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take the new value as a string and return a string; they are
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usually less efficient than \fBTcl_ObjSetVar2\fR. Note that the
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return value may be different than the \fInewValuePtr\fR or
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\fInewValue\fR argument, due to modifications made by write traces.
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If an error occurs in setting the variable (e.g. an array
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variable is referenced without giving an index into the array)
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NULL is returned and an error message is left in \fIinterp\fR's
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result if the \fBTCL_LEAVE_ERR_MSG\fR \fIflag\fR bit is set.
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.PP
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\fBTcl_GetVar2Ex\fR, \fBTcl_GetVar\fR, \fBTcl_GetVar2\fR, and
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\fBTcl_ObjGetVar2\fR
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return the current value of a variable.
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The arguments to these procedures are treated in the same way
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as the arguments to the procedures described above.
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Under normal circumstances, the return value is a pointer
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to the variable's value. For \fBTcl_GetVar2Ex\fR and
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\fBTcl_ObjGetVar2\fR the value is
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returned as a pointer to a Tcl_Obj. For \fBTcl_GetVar\fR and
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\fBTcl_GetVar2\fR the value is returned as a string; this is
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usually less efficient, so \fBTcl_GetVar2Ex\fR or \fBTcl_ObjGetVar2\fR
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are preferred.
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If an error occurs while reading the variable (e.g. the variable
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does not exist or an array element is specified for a scalar
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variable), then NULL is returned and an error message is left
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in \fIinterp\fR's result if the \fBTCL_LEAVE_ERR_MSG\fR \fIflag\fR
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bit is set.
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.PP
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\fBTcl_UnsetVar\fR and \fBTcl_UnsetVar2\fR may be used to remove
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a variable, so that future attempts to read the variable will return
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an error.
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The arguments to these procedures are treated in the same way
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as the arguments to the procedures above.
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If the variable is successfully removed then \fBTCL_OK\fR is returned.
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If the variable cannot be removed because it does not exist then
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\fBTCL_ERROR\fR is returned and an error message is left
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in \fIinterp\fR's result if the \fBTCL_LEAVE_ERR_MSG\fR \fIflag\fR
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bit is set.
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If an array element is specified, the given element is removed
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but the array remains.
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If an array name is specified without an index, then the entire
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array is removed.
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.PP
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The name of a variable may be specified to these procedures in
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four ways:
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.IP [1]
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If \fBTcl_SetVar\fR, \fBTcl_GetVar\fR, or \fBTcl_UnsetVar\fR
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is invoked, the variable name is given as
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a single string, \fIvarName\fR.
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If \fIvarName\fR contains an open parenthesis and ends with a
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close parenthesis, then the value between the parentheses is
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treated as an index (which can have any string value) and
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the characters before the first open
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parenthesis are treated as the name of an array variable.
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If \fIvarName\fR does not have parentheses as described above, then
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the entire string is treated as the name of a scalar variable.
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.IP [2]
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If the \fIname1\fR and \fIname2\fR arguments are provided and
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\fIname2\fR is non-NULL, then an array element is specified and
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the array name and index have
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already been separated by the caller: \fIname1\fR contains the
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name and \fIname2\fR contains the index. An error is generated
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if \fIname1\fR contains an open parenthesis and ends with a
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close parenthesis (array element) and \fIname2\fR is non-NULL.
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.IP [3]
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If \fIname2\fR is NULL, \fIname1\fR is treated just like
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\fIvarName\fR in case [1] above (it can be either a scalar or an array
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element variable name).
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.PP
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The \fIflags\fR argument may be used to specify any of several
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options to the procedures.
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It consists of an OR-ed combination of the following bits.
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.TP
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\fBTCL_GLOBAL_ONLY\fR
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Under normal circumstances the procedures look up variables as follows.
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If a procedure call is active in \fIinterp\fR,
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the variable is looked up at the current level of procedure call.
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Otherwise, the variable is looked up first in the current namespace,
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then in the global namespace.
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However, if this bit is set in \fIflags\fR then the variable
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is looked up only in the global namespace
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even if there is a procedure call active.
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If both \fBTCL_GLOBAL_ONLY\fR and \fBTCL_NAMESPACE_ONLY\fR are given,
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\fBTCL_GLOBAL_ONLY\fR is ignored.
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.TP
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\fBTCL_NAMESPACE_ONLY\fR
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If this bit is set in \fIflags\fR then the variable
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is looked up only in the current namespace; if a procedure is active
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its variables are ignored, and the global namespace is also ignored unless
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it is the current namespace.
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.TP
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\fBTCL_LEAVE_ERR_MSG\fR
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If an error is returned and this bit is set in \fIflags\fR, then
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an error message will be left in the interpreter's result,
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where it can be retrieved with \fBTcl_GetObjResult\fR
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or \fBTcl_GetStringResult\fR.
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If this flag bit is not set then no error message is left
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and the interpreter's result will not be modified.
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.TP
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\fBTCL_APPEND_VALUE\fR
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If this bit is set then \fInewValuePtr\fR or \fInewValue\fR is
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appended to the current value instead of replacing it.
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If the variable is currently undefined, then the bit is ignored.
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This bit is only used by the \fBTcl_Set*\fR procedures.
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.TP
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\fBTCL_LIST_ELEMENT\fR
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If this bit is set, then \fInewValue\fR is converted to a valid
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Tcl list element before setting (or appending to) the variable.
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A separator space is appended before the new list element unless
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the list element is going to be the first element in a list or
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sublist (i.e. the variable's current value is empty, or contains
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the single character
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.QW { ,
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or ends in
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.QW " }" ).
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When appending, the original value of the variable must also be
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a valid list, so that the operation is the appending of a new
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list element onto a list.
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.PP
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\fBTcl_GetVar\fR and \fBTcl_GetVar2\fR
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return the current value of a variable.
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The arguments to these procedures are treated in the same way
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as the arguments to \fBTcl_SetVar\fR and \fBTcl_SetVar2\fR.
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Under normal circumstances, the return value is a pointer
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to the variable's value (which is stored in Tcl's variable
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structure and will not change before the next call to \fBTcl_SetVar\fR
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or \fBTcl_SetVar2\fR).
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\fBTcl_GetVar\fR and \fBTcl_GetVar2\fR use the flag bits \fBTCL_GLOBAL_ONLY\fR
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and \fBTCL_LEAVE_ERR_MSG\fR, both of
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which have
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the same meaning as for \fBTcl_SetVar\fR.
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If an error occurs in reading the variable (e.g. the variable
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does not exist or an array element is specified for a scalar
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variable), then NULL is returned.
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.PP
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\fBTcl_UnsetVar\fR and \fBTcl_UnsetVar2\fR may be used to remove
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a variable, so that future calls to \fBTcl_GetVar\fR or \fBTcl_GetVar2\fR
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for the variable will return an error.
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The arguments to these procedures are treated in the same way
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as the arguments to \fBTcl_GetVar\fR and \fBTcl_GetVar2\fR.
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If the variable is successfully removed then \fBTCL_OK\fR is returned.
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If the variable cannot be removed because it does not exist then
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\fBTCL_ERROR\fR is returned.
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If an array element is specified, the given element is removed
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but the array remains.
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If an array name is specified without an index, then the entire
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array is removed.
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.SH "SEE ALSO"
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Tcl_GetObjResult, Tcl_GetStringResult, Tcl_TraceVar
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.SH KEYWORDS
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array, get variable, interpreter, scalar, set, unset, value, variable
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