| '\" |
| '\" 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. |
| '\" |
| '\" RCS: @(#) $Id: Interp.3,v 1.3 2000/04/14 23:01:51 hobbs Exp $ |
| '\" |
| '\" The 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 |
| '\" Start of list of standard options for a Tk widget. The |
| '\" options follow on successive lines, in four 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. |
| '\" |
| '\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $ |
| '\" |
| '\" # 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 |
| .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 \\fBoptions\\fR 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 |
| .. |
| .de UL |
| \\$1\l'|0\(ul'\\$2 |
| .. |
| .TH Tcl_Interp 3 7.5 Tcl "Tcl Library Procedures" |
| .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; |
| } Tcl_Interp; |
| |
| typedef void Tcl_FreeProc(char *\fIblockPtr\fR); |
| .BE |
| |
| .SH DESCRIPTION |
| .PP |
| The \fBTcl_CreateInterp\fR procedure returns a pointer to a Tcl_Interp |
| structure. This pointer is then passed into other Tcl procedures |
| to process commands in the interpreter and perform other operations |
| on the interpreter. Interpreter structures contain many many fields |
| that are used by Tcl, but only three that may be accessed by |
| clients: \fIresult\fR, \fIfreeProc\fR, and \fIerrorLine\fR. |
| .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 isn't 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. |
| .VS |
| 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. |
| .VE |
| 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. |
| .VS |
| In most applications \fBTCL_DYNAMIC\fR is the only non-zero value ever |
| used for \fIfreeProc\fR. |
| .VE |
| 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 |