Please enter the commit message for your changes. Lines starting

[eos/hostdependX86LINUX64.git] / util / X86LINUX64 / man / man3 / Tcl_Interp.3

'\"
'\" Copyright (c) 1989-1993 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 Tcl_Interp 3 7.5 Tcl "Tcl Library Procedures"
.\" The -*- nroff -*- definitions below are for supplemental macros used
.\" in Tcl/Tk manual entries.
.\"
.\" .AP type name in/out ?indent?
.\"     Start paragraph describing an argument to a library procedure.
.\"     type is type of argument (int, etc.), in/out is either "in", "out",
.\"     or "in/out" to describe whether procedure reads or modifies arg,
.\"     and indent is equivalent to second arg of .IP (shouldn't ever be
.\"     needed;  use .AS below instead)
.\"
.\" .AS ?type? ?name?
.\"     Give maximum sizes of arguments for setting tab stops.  Type and
.\"     name are examples of largest possible arguments that will be passed
.\"     to .AP later.  If args are omitted, default tab stops are used.
.\"
.\" .BS
.\"     Start box enclosure.  From here until next .BE, everything will be
.\"     enclosed in one large box.
.\"
.\" .BE
.\"     End of box enclosure.
.\"
.\" .CS
.\"     Begin code excerpt.
.\"
.\" .CE
.\"     End code excerpt.
.\"
.\" .VS ?version? ?br?
.\"     Begin vertical sidebar, for use in marking newly-changed parts
.\"     of man pages.  The first argument is ignored and used for recording
.\"     the version when the .VS was added, so that the sidebars can be
.\"     found and removed when they reach a certain age.  If another argument
.\"     is present, then a line break is forced before starting the sidebar.
.\"
.\" .VE
.\"     End of vertical sidebar.
.\"
.\" .DS
.\"     Begin an indented unfilled display.
.\"
.\" .DE
.\"     End of indented unfilled display.
.\"
.\" .SO ?manpage?
.\"     Start of list of standard options for a Tk widget. The manpage
.\"     argument defines where to look up the standard options; if
.\"     omitted, defaults to "options". The options follow on successive
.\"     lines, in three columns separated by tabs.
.\"
.\" .SE
.\"     End of list of standard options for a Tk widget.
.\"
.\" .OP cmdName dbName dbClass
.\"     Start of description of a specific option.  cmdName gives the
.\"     option's name as specified in the class command, dbName gives
.\"     the option's name in the option database, and dbClass gives
.\"     the option's class in the option database.
.\"
.\" .UL arg1 arg2
.\"     Print arg1 underlined, then print arg2 normally.
.\"
.\" .QW arg1 ?arg2?
.\"     Print arg1 in quotes, then arg2 normally (for trailing punctuation).
.\"
.\" .PQ arg1 ?arg2?
.\"     Print an open parenthesis, arg1 in quotes, then arg2 normally
.\"     (for trailing punctuation) and then a closing parenthesis.
.\"
.\"     # Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
.if t .wh -1.3i ^B
.nr ^l \n(.l
.ad b
.\"     # Start an argument description
.de AP
.ie !"\\$4"" .TP \\$4
.el \{\
.   ie !"\\$2"" .TP \\n()Cu
.   el          .TP 15
.\}
.ta \\n()Au \\n()Bu
.ie !"\\$3"" \{\
\&\\$1 \\fI\\$2\\fP (\\$3)
.\".b
.\}
.el \{\
.br
.ie !"\\$2"" \{\
\&\\$1  \\fI\\$2\\fP
.\}
.el \{\
\&\\fI\\$1\\fP
.\}
.\}
..
.\"     # define tabbing values for .AP
.de AS
.nr )A 10n
.if !"\\$1"" .nr )A \\w'\\$1'u+3n
.nr )B \\n()Au+15n
.\"
.if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n
.nr )C \\n()Bu+\\w'(in/out)'u+2n
..
.AS Tcl_Interp Tcl_CreateInterp in/out
.\"     # BS - start boxed text
.\"     # ^y = starting y location
.\"     # ^b = 1
.de BS
.br
.mk ^y
.nr ^b 1u
.if n .nf
.if n .ti 0
.if n \l'\\n(.lu\(ul'
.if n .fi
..
.\"     # BE - end boxed text (draw box now)
.de BE
.nf
.ti 0
.mk ^t
.ie n \l'\\n(^lu\(ul'
.el \{\
.\"     Draw four-sided box normally, but don't draw top of
.\"     box if the box started on an earlier page.
.ie !\\n(^b-1 \{\
\h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
.\}
.el \}\
\h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
.\}
.\}
.fi
.br
.nr ^b 0
..
.\"     # VS - start vertical sidebar
.\"     # ^Y = starting y location
.\"     # ^v = 1 (for troff;  for nroff this doesn't matter)
.de VS
.if !"\\$2"" .br
.mk ^Y
.ie n 'mc \s12\(br\s0
.el .nr ^v 1u
..
.\"     # VE - end of vertical sidebar
.de VE
.ie n 'mc
.el \{\
.ev 2
.nf
.ti 0
.mk ^t
\h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n'
.sp -1
.fi
.ev
.\}
.nr ^v 0
..
.\"     # Special macro to handle page bottom:  finish off current
.\"     # box/sidebar if in box/sidebar mode, then invoked standard
.\"     # page bottom macro.
.de ^B
.ev 2
'ti 0
'nf
.mk ^t
.if \\n(^b \{\
.\"     Draw three-sided box if this is the box's first page,
.\"     draw two sides but no top otherwise.
.ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
.el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
.\}
.if \\n(^v \{\
.nr ^x \\n(^tu+1v-\\n(^Yu
\kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c
.\}
.bp
'fi
.ev
.if \\n(^b \{\
.mk ^y
.nr ^b 2
.\}
.if \\n(^v \{\
.mk ^Y
.\}
..
.\"     # DS - begin display
.de DS
.RS
.nf
.sp
..
.\"     # DE - end display
.de DE
.fi
.RE
.sp
..
.\"     # SO - start of list of standard options
.de SO
'ie '\\$1'' .ds So \\fBoptions\\fR
'el .ds So \\fB\\$1\\fR
.SH "STANDARD OPTIONS"
.LP
.nf
.ta 5.5c 11c
.ft B
..
.\"     # SE - end of list of standard options
.de SE
.fi
.ft R
.LP
See the \\*(So manual entry for details on the standard options.
..
.\"     # OP - start of full description for a single option
.de OP
.LP
.nf
.ta 4c
Command-Line Name:      \\fB\\$1\\fR
Database Name:  \\fB\\$2\\fR
Database Class: \\fB\\$3\\fR
.fi
.IP
..
.\"     # CS - begin code excerpt
.de CS
.RS
.nf
.ta .25i .5i .75i 1i
..
.\"     # CE - end code excerpt
.de CE
.fi
.RE
..
.\"     # UL - underline word
.de UL
\\$1\l'|0\(ul'\\$2
..
.\"     # QW - apply quotation marks to word
.de QW
.ie '\\*(lq'"' ``\\$1''\\$2
.\"" fix emacs highlighting
.el \\*(lq\\$1\\*(rq\\$2
..
.\"     # PQ - apply parens and quotation marks to word
.de PQ
.ie '\\*(lq'"' (``\\$1''\\$2)\\$3
.\"" fix emacs highlighting
.el (\\*(lq\\$1\\*(rq\\$2)\\$3
..
.\"     # QR - quoted range
.de QR
.ie '\\*(lq'"' ``\\$1''\\-``\\$2''\\$3
.\"" fix emacs highlighting
.el \\*(lq\\$1\\*(rq\\-\\*(lq\\$2\\*(rq\\$3
..
.\"     # MT - "empty" string
.de MT
.QW ""
..
.BS
.SH NAME
Tcl_Interp \- client-visible fields of interpreter structures
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
typedef struct {
    char *\fIresult\fR;
    Tcl_FreeProc *\fIfreeProc\fR;
    int \fIerrorLine\fR;
} \fBTcl_Interp\fR;

typedef void \fBTcl_FreeProc\fR(
        char *\fIblockPtr\fR);
.BE
.SH DESCRIPTION
.PP
The \fBTcl_CreateInterp\fR procedure returns a pointer to a Tcl_Interp
structure.  Callers of \fBTcl_CreateInterp\fR should use this pointer
as an opaque token, suitable for nothing other than passing back to
other routines in the Tcl interface.  Accessing fields directly through
the pointer as described below is no longer supported.  The supported
public routines \fBTcl_SetResult\fR, \fBTcl_GetResult\fR,
\fBTcl_SetErrorLine\fR, \fBTcl_GetErrorLine\fR must be used instead.
.PP
For legacy programs and extensions no longer being maintained, compiles
against the Tcl 8.6 header files are only possible with the compiler
directives
.CS
#define USE_INTERP_RESULT
.CE
and/or
.CS
#define USE_INTERP_ERRORLINE
.CE
depending on which fields of the \fBTcl_Interp\fR struct are accessed.
These directives may be embedded in code or supplied via compiler options.
.PP
The \fIresult\fR and \fIfreeProc\fR fields are used to return
results or error messages from commands.
This information is returned by command procedures back to \fBTcl_Eval\fR,
and by \fBTcl_Eval\fR back to its callers.
The \fIresult\fR field points to the string that represents the
result or error message, and the \fIfreeProc\fR field tells how
to dispose of the storage for the string when it is not needed anymore.
The easiest way for command procedures to manipulate these
fields is to call procedures like \fBTcl_SetResult\fR
or \fBTcl_AppendResult\fR;  they
will hide all the details of managing the fields.
The description below is for those procedures that manipulate the
fields directly.
.PP
Whenever a command procedure returns, it must ensure
that the \fIresult\fR field of its interpreter points to the string
being returned by the command.
The \fIresult\fR field must always point to a valid string.
If a command wishes to return no result then \fIinterp->result\fR
should point to an empty string.
Normally, results are assumed to be statically allocated,
which means that the contents will not change before the next time
\fBTcl_Eval\fR is called or some other command procedure is invoked.
In this case, the \fIfreeProc\fR field must be zero.
Alternatively, a command procedure may dynamically
allocate its return value (e.g. using \fBTcl_Alloc\fR)
and store a pointer to it in \fIinterp->result\fR.
In this case, the command procedure must also set \fIinterp->freeProc\fR
to the address of a procedure that can free the value, or \fBTCL_DYNAMIC\fR
if the storage was allocated directly by Tcl or by a call to
\fBTcl_Alloc\fR. 
If \fIinterp->freeProc\fR is non-zero, then Tcl will call \fIfreeProc\fR
to free the space pointed to by \fIinterp->result\fR before it
invokes the next command.
If a client procedure overwrites \fIinterp->result\fR when
\fIinterp->freeProc\fR is non-zero, then it is responsible for calling
\fIfreeProc\fR to free the old \fIinterp->result\fR (the \fBTcl_FreeResult\fR
macro should be used for this purpose).
.PP
\fIFreeProc\fR should have arguments and result that match the
\fBTcl_FreeProc\fR declaration above:  it receives a single
argument which is a pointer to the result value to free.
In most applications \fBTCL_DYNAMIC\fR is the only non-zero value ever
used for \fIfreeProc\fR.
However, an application may store a different procedure address
in \fIfreeProc\fR in order to use an alternate memory allocator
or in order to do other cleanup when the result memory is freed.
.PP
As part of processing each command, \fBTcl_Eval\fR initializes
\fIinterp->result\fR
and \fIinterp->freeProc\fR just before calling the command procedure for
the command.  The \fIfreeProc\fR field will be initialized to zero,
and \fIinterp->result\fR will point to an empty string.  Commands that
do not return any value can simply leave the fields alone.
Furthermore, the empty string pointed to by \fIresult\fR is actually
part of an array of \fBTCL_RESULT_SIZE\fR characters (approximately 200).
If a command wishes to return a short string, it can simply copy
it to the area pointed to by \fIinterp->result\fR.  Or, it can use
the sprintf procedure to generate a short result string at the location
pointed to by \fIinterp->result\fR.
.PP
It is a general convention in Tcl-based applications that the result
of an interpreter is normally in the initialized state described
in the previous paragraph.
Procedures that manipulate an interpreter's result (e.g. by
returning an error) will generally assume that the result
has been initialized when the procedure is called.
If such a procedure is to be called after the result has been
changed, then \fBTcl_ResetResult\fR should be called first to
reset the result to its initialized state.  The direct use of
\fIinterp->result\fR is strongly deprecated (see \fBTcl_SetResult\fR).
.PP
The \fIerrorLine\fR
field is valid only after \fBTcl_Eval\fR returns
a \fBTCL_ERROR\fR return code.  In this situation the \fIerrorLine\fR
field identifies the line number of the command being executed when
the error occurred.  The line numbers are relative to the command
being executed:  1 means the first line of the command passed to
\fBTcl_Eval\fR, 2 means the second line, and so on.
The \fIerrorLine\fR field is typically used in conjunction with
\fBTcl_AddErrorInfo\fR to report information about where an error
occurred.
\fIErrorLine\fR should not normally be modified except by \fBTcl_Eval\fR.

.SH KEYWORDS
free, initialized, interpreter, malloc, result