163 lines
5.8 KiB
Groff
163 lines
5.8 KiB
Groff
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'\"
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'\" Copyright (c) 1989-1993 The Regents of the University of California.
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'\" Copyright (c) 1994-1996 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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'\" SCCS: @(#) SetVar.3 1.22 96/03/25 20:07:08
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'\"
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.so man.macros
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.TH Tcl_SetVar 3 7.4 Tcl "Tcl Library Procedures"
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.BS
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.SH NAME
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Tcl_SetVar, Tcl_SetVar2, Tcl_GetVar, Tcl_GetVar2, 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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char *
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\fBTcl_SetVar\fR(\fIinterp, varName, newValue, flags\fR)
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.sp
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char *
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\fBTcl_SetVar2\fR(\fIinterp, name1, name2, newValue, flags\fR)
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.sp
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char *
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\fBTcl_GetVar\fR(\fIinterp, varName, flags\fR)
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.sp
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char *
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\fBTcl_GetVar2\fR(\fIinterp, name1, name2, 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 *newValue
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.AP Tcl_Interp *interp in
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Interpreter containing variable.
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.AP char *varName in
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Name of variable. May refer to a scalar variable or an element of
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an array variable.
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.VS
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If the name references an element of an array, then it
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must be in writable memory: Tcl will make temporary modifications
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to it while looking up the name.
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.VE
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.AP char *newValue in
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New value for variable.
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.AP int flags in
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OR-ed combination of bits providing additional information for
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operation. See below for valid values.
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.AP char *name1 in
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Name of scalar variable, or name of array variable if \fIname2\fR
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is non-NULL.
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.AP char *name2 in
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If non-NULL, gives name of element within array and \fIname1\fR
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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 may be used to create, modify, read, and delete
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Tcl variables from C code.
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\fBTcl_SetVar\fR and \fBTcl_SetVar2\fR will create a new variable
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or modify an existing one.
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Both of these procedures set the given variable to the value
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given by \fInewValue\fR, and they return a pointer to a
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copy of the variable's new value, which is stored in Tcl's
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variable structure.
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Tcl keeps a private copy of the variable's value, so the caller
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may change \fInewValue\fR after these procedures return without
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affecting the value of the variable.
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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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then NULL is returned.
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.PP
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The name of the variable may be specified in either of two ways.
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If \fBTcl_SetVar\fR is called, 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 doesn't 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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If \fBTcl_SetVar2\fR is called, then the array name and index
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have been separated by the caller into two separate strings,
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\fIname1\fR and \fIname2\fR respectively; if \fIname2\fR is
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zero it means that a scalar variable is being referenced.
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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 any of the following
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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
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at the current level of procedure call for \fIinterp\fR, or
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at global level if there is no call active.
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However, if this bit is set in \fIflags\fR then the variable
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is looked up at global level even if there is a procedure
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call active.
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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 \fI\%interp->result\fR. If this
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flag bit isn't set then no error message is left (\fI\%interp->result\fR
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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 \fInewValue\fR is appended to the current
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value, instead of replacing it.
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If the variable is currently undefined, then this bit is ignored.
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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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.VS
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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 ``{'', or ends in `` }'').
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.VE
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.PP
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\fBTcl_GetVar\fR and \fBTcl_GetVar2\fR return the current value
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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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The only bits of \fIflags\fR that are used are TCL_GLOBAL_ONLY
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and TCL_LEAVE_ERR_MSG, 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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doesn't 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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.VS
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If the variable is successfully removed then TCL_OK is returned.
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If the variable cannot be removed because it doesn't exist then
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TCL_ERROR is returned.
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.VE
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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_TraceVar
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.SH KEYWORDS
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array, interpreter, scalar, set, unset, variable
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