path: root/doc/SetResult.3

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.TH Tcl_SetResult 3 8.7 Tcl "Tcl Library Procedures"
.so man.macros
.BS
.SH NAME
Tcl_SetObjResult, Tcl_GetObjResult, Tcl_SetResult, Tcl_GetStringResult, Tcl_AppendResult, Tcl_AppendElement, Tcl_ResetResult, Tcl_TransferResult \- manipulate Tcl result
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
\fBTcl_SetObjResult\fR(\fIinterp, objPtr\fR)
.sp
Tcl_Obj *
\fBTcl_GetObjResult\fR(\fIinterp\fR)
.sp
\fBTcl_SetResult\fR(\fIinterp, result, freeProc\fR)
.sp
const char *
\fBTcl_GetStringResult\fR(\fIinterp\fR)
.sp
\fBTcl_AppendResult\fR(\fIinterp, result, result, ... , \fB(char *)NULL\fR)
.sp
\fBTcl_ResetResult\fR(\fIinterp\fR)
.sp
\fBTcl_TransferResult\fR(\fIsourceInterp, code, targetInterp\fR)
.sp
\fBTcl_AppendElement\fR(\fIinterp, element\fR)
.fi
.SH ARGUMENTS
.AS Tcl_FreeProc sourceInterp out
.AP Tcl_Interp *interp out
The interpreter get or set the result for.
.AP Tcl_Obj *objPtr in
A value to set the result to.
.AP char *result in
The string value set the result to, or to append to the existing result.
.AP "const char" *element in
The string value to append as a list element
to the existing result of \fIinterp\fR.
.AP Tcl_FreeProc *freeProc in
Pointer to a procedure to call to release storage at
\fIresult\fR.
.AP Tcl_Interp *sourceInterp in
The interpreter to transfer the result and return options from.
.AP Tcl_Interp *targetInterp in
The interpreter to transfer the result and return options to.
.AP int code in
Return code value that controls transfer of return options.
.BE
.SH DESCRIPTION
.PP
These procedures manipulate the result of an interpreter.  Some procedures
provide a Tcl_Obj interface while others provide a string interface.  For
example, \fBTcl_SetObjResult\fR accepts a Tcl_Obj and \fBTcl_SetResult\fR
accepts a char *.  Similarly, \fBTcl_GetObjResult\fR produces a Tcl_Obj * and
\fBTcl_GetStringResult\fR produces a char *.  The procedures can be mixed and
matched.  For example, if \fBTcl_SetObjResult\fR is called to set the result to
a Tcl_Obj value, and then \fBTcl_GetStringResult\fR is called, it returns a
char * (but see caveats below).
.PP
\fBTcl_SetObjResult\fR sets \fIobjPtr\fR as the result for \fIinterp\fR,
replacing any existing result.
.PP
\fBTcl_GetObjResult\fR returns the result for \fIinterp\fR, without
incrementing its reference count.
.PP
\fBTcl_SetResult\fR sets \fIresult\fR as the result for \fIinterp\fR, replacing
any existing result, and calls \fIfreeProc\fR to free \fIresult\fR.  See \fBTHE
TCL_FREEPROC ARGUMENT TO TCL_SETRESULT\fR below.  If \fIresult\fR is
\fBNULL\fR, ignores \fIfreeProc\fR and sets the result for \fIinterp\fR to
point to the empty string.
.PP
\fBTcl_GetStringResult\fR returns the result for \fIinterp\fR as a string, i.e.
the bytes of the Tcl_Obj for the result, which can be decoded using
\fBTcl_UtfToExternal\fR.  This value is freed when its corresponding Tcl_Obj is
freed.Programmers are encouraged to use the newer Tcl_Obj API procedures, e.g.
to call \fBTcl_GetObjResult\fR instead.
.PP
\fBTcl_ResetResult\fR sets the empty string as the result for \fIinterp\fR and
clears the error state managed by \fBTcl_AddErrorInfo\fR,
\fBTcl_AddObjErrorInfo\fR, and \fBTcl_SetErrorCode\fR.
.PP
\fBTcl_AppendResult\fR builds up a result from smaller pieces, appending each
\fIresult\fR in order to the current result for \fIinterp\fR.  It may be called
repeatedly as additional pieces of the result are produced, and manages the
storage for the \fIinterp\fR's result, allocating a larger result area if
necessary.  It also manages conversion to and from the \fIresult\fR field of
the \fIinterp\fR to handle backward-compatibility with old-style extensions.
Any number of \fIresult\fR arguments may be passed in a single call; the last
argument in the list must be (char *)NULL.
.PP
\fBTcl_TransferResult\fR transfers interpreter state from \fIsourceInterp\fR to
\fItargetInterp\fR, both of which must have been created in the same thread,
resets the result in \fIsourceInterp\fR, and moves the return options
dictionary as controlled by the return code value \fIcode\fR in the same manner
as \fBTcl_GetReturnOptions\fR.
.PP
If \fIsourceInterp\fR and \fItargetInterp\fR are the same, nothing is done.
.SH "DEPRECATED INTERFACES"
.SS "OLD STRING PROCEDURES"
.PP
The following procedures are deprecated since they manipulate the Tcl result as
a string.  Procedures such as \fBTcl_SetObjResult\fR can be significantly more
efficient.
.PP
\fBTcl_AppendElement\fR is like \fBTcl_AppendResult\fR, but it appends only one
piece, and also appends that piece as a list item.
\fBTcl_AppendElement\fR adds backslashes or braces as necessary to ensure that
\fIelement\fR is properly formatted as a list item.  Under normal conditions,
\fBTcl_AppendElement\fR adds a space character to \fIinterp\fR's result just
before adding the new list element, so that the list elements in the result are
properly separated.  However if the new list element is the first item in the
list or sublist (i.e. \fIinterp\fR's current result is empty, or consists of
the single character
.QW { ,
or ends in the characters
.QW " {" )
then no space is added.
.SH "THE TCL_FREEPROC ARGUMENT TO TCL_SETRESULT"
.PP
\fIFreeProc\fR has the following type:
.PP
.CS
typedef void \fBTcl_FreeProc\fR(
        char *\fIblockPtr\fR);
.CE
.PP
When \fIfreeProc\fR is called, \fIblockPtr\fR is the \fIresult\fR value passed
to \fBTcl_SetResult\fR.

.SH "SEE ALSO"
Tcl_AddErrorInfo, Tcl_CreateObjCommand, Tcl_SetErrorCode, Tcl_Interp,
Tcl_GetReturnOptions
.SH KEYWORDS
append, command, element, list, value, result, return value, interpreter