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- '\" $Header: /user6/ouster/tcl/man/RCS/SetVar.3,v 1.15 93/06/05 15:40:17 ouster Exp $ SPRITE (Berkeley)
- '\"
- .\" The definitions below are for supplemental macros used in Tcl/Tk
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- .HS Tcl_SetVar tclc 7.0
- .BS
- .SH NAME
- Tcl_SetVar, Tcl_SetVar2, Tcl_GetVar, Tcl_GetVar2, Tcl_UnsetVar, Tcl_UnsetVar2 \- manipulate Tcl variables
- .SH SYNOPSIS
- .nf
- \fB#include <tcl.h>\fR
- .sp
- char *
- \fBTcl_SetVar\fR(\fIinterp, varName, newValue, flags\fR)
- .sp
- char *
- \fBTcl_SetVar2\fR(\fIinterp, name1, name2, newValue, flags\fR)
- .sp
- char *
- \fBTcl_GetVar\fR(\fIinterp, varName, flags\fR)
- .sp
- char *
- \fBTcl_GetVar2\fR(\fIinterp, name1, name2, flags\fR)
- .sp
- int
- \fBTcl_UnsetVar\fR(\fIinterp, varName, flags\fR)
- .sp
- int
- \fBTcl_UnsetVar2\fR(\fIinterp, name1, name2, flags\fR)
- .SH ARGUMENTS
- .AS Tcl_Interp *newValue
- .AP Tcl_Interp *interp in
- Interpreter containing variable.
- .AP char *varName in
- Name of variable. May refer to a scalar variable or an element of
- an array variable.
- .AP char *newValue in
- New value for variable.
- .AP int flags in
- OR-ed combination of bits providing additional information for
- operation. See below for valid values.
- .AP char *name1 in
- Name of scalar variable, or name of array variable if \fIname2\fR
- is non-NULL.
- .AP char *name2 in
- If non-NULL, gives name of element within array and \fIname1\fR
- must refer to an array variable.
- .BE
-
- .SH DESCRIPTION
- .PP
- These procedures may be used to create, modify, read, and delete
- Tcl variables from C code.
- \fBTcl_SetVar\fR and \fBTcl_SetVar2\fR will create a new variable
- or modify an existing one.
- Both of these procedures set the given variable to the value
- given by \fInewValue\fR, and they return a pointer to a
- copy of the variable's new value, which is stored in Tcl's
- variable structure.
- Tcl keeps a private copy of the variable's value, so the caller
- may change \fInewValue\fR after these procedures return without
- affecting the value of the variable.
- If an error occurs in setting the variable (e.g. an array
- variable is referenced without giving an index into the array),
- then NULL is returned.
- .PP
- The name of the variable may be specified in either of two ways.
- If \fBTcl_SetVar\fR is called, the variable name is given as
- a single string, \fIvarName\fR.
- If \fIvarName\fR contains an open parenthesis and ends with a
- close parenthesis, then the value between the parentheses is
- treated as an index (which can have any string value) and
- the characters before the first open
- parenthesis are treated as the name of an array variable.
- If \fIvarName\fR doesn't have parentheses as described above, then
- the entire string is treated as the name of a scalar variable.
- If \fBTcl_SetVar2\fR is called, then the array name and index
- have been separated by the caller into two separate strings,
- \fIname1\fR and \fIname2\fR respectively; if \fIname2\fR is
- zero it means that a scalar variable is being referenced.
- .PP
- The \fIflags\fR argument may be used to specify any of several
- options to the procedures.
- It consists of an OR-ed combination of any of the following
- bits:
- .IP TCL_GLOBAL_ONLY
- Under normal circumstances the procedures look up variables
- at the current level of procedure call for \fIinterp\fR, or
- at global level if there is no call active.
- However, if this bit is set in \fIflags\fR then the variable
- is looked up at global level even if there is a procedure
- call active.
- .IP TCL_LEAVE_ERR_MSG
- If an error is returned and this bit is set in \fIflags\fR, then
- an error message will be left in \fI\%interp->result\fR. If this
- flag bit isn't set then no error message is left (\fI\%interp->result\fR
- will not be modified).
- .IP TCL_APPEND_VALUE
- If this bit is set then \fInewValue\fR is appended to the current
- value, instead of replacing it.
- If the variable is currently undefined, then this bit is ignored.
- .IP TCL_LIST_ELEMENT
- If this bit is set, then \fInewValue\fR is converted to a valid
- Tcl list element before setting (or appending to) the variable.
- A separator space is appended before the new list element unless
- .VS
- the list element is going to be the first element in a list or
- sublist (i.e. the variable's current value is empty, or contains
- the single character ``{'', or ends in `` }'').
- .VE
- .PP
- \fBTcl_GetVar\fR and \fBTcl_GetVar2\fR return the current value
- of a variable.
- The arguments to these procedures are treated in the same way
- as the arguments to \fBTcl_SetVar\fR and \fBTcl_SetVar2\fR.
- Under normal circumstances, the return value is a pointer
- to the variable's value (which is stored in Tcl's variable
- structure and will not change before the next call to \fBTcl_SetVar\fR
- or \fBTcl_SetVar2\fR).
- The only bits of \fIflags\fR that are used are TCL_GLOBAL_ONLY
- and TCL_LEAVE_ERR_MSG, both of
- which have
- the same meaning as for \fBTcl_SetVar\fR.
- If an error occurs in reading the variable (e.g. the variable
- doesn't exist or an array element is specified for a scalar
- variable), then NULL is returned.
- .PP
- \fBTcl_UnsetVar\fR and \fBTcl_UnsetVar2\fR may be used to remove
- a variable, so that future calls to \fBTcl_GetVar\fR or \fBTcl_GetVar2\fR
- for the variable will return an error.
- The arguments to these procedures are treated in the same way
- as the arguments to \fBTcl_GetVar\fR and \fBTcl_GetVar2\fR.
- .VS
- If the variable is successfully removed then TCL_OK is returned.
- If the variable cannot be removed because it doesn't exist then
- TCL_ERROR is returned.
- .VE
- If an array element is specified, the given element is removed
- but the array remains.
- If an array name is specified without an index, then the entire
- array is removed.
-
- .SH "SEE ALSO"
- Tcl_TraceVar
-
- .SH KEYWORDS
- array, interpreter, scalar, set, unset, variable
-