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'\"
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'\" Copyright (c) 1996-1997 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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'\" RCS: @(#) $Id: EvalObj.3,v 1.1.1.1 2002-01-16 10:25:23 markom Exp $
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'\"
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.so man.macros
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.TH Tcl_EvalObj 3 8.0 Tcl "Tcl Library Procedures"
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.BS
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.SH NAME
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Tcl_EvalObj, Tcl_GlobalEvalObj \- execute Tcl commands
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.SH SYNOPSIS
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.nf
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\fB#include \fR
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.sp
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int
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\fBTcl_EvalObj\fR(\fIinterp, objPtr\fR)
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.sp
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int
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\fBTcl_GlobalEvalObj\fR(\fIinterp, objPtr\fR)
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.SH ARGUMENTS
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.AS Tcl_Interp **termPtr;
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.AP Tcl_Interp *interp in
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Interpreter in which to execute the command.
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The command's result will be stored in the interpreter's result object
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and can be retrieved using \fBTcl_GetObjResult\fR.
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.AP Tcl_Obj *objPtr in
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A Tcl object containing a command string
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(or sequence of commands in a string) to execute.
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.BE
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.SH DESCRIPTION
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.PP
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These two procedures execute Tcl commands.
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\fBTcl_EvalObj\fR is the core procedure
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and is used by \fBTcl_GlobalEvalObj\fR.
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It executes the commands in the script held by \fIobjPtr\fR
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until either an error occurs or it reaches the end of the script.
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If this is the first time \fIobjPtr\fR has been executed,
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its commands are compiled into bytecode instructions
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that are then executed if there are no compilation errors.
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.PP
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The return value from \fBTcl_EvalObj\fR is one of the Tcl return codes
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\fBTCL_OK\fR, \fBTCL_ERROR\fR, \fBTCL_RETURN\fR, \fBTCL_BREAK\fR, or
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\fBTCL_CONTINUE\fR,
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and a result object containing additional information
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(a result value or error message)
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that can be retrieved using \fBTcl_GetObjResult\fR.
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If an error occurs during compilation, this return information
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describes the error.
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Otherwise, this return information corresponds to the last command
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executed from \fIobjPtr\fR.
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.PP
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\fBTcl_GlobalEvalObj\fR is similar to \fBTcl_EvalObj\fR except that it
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processes the command at global level.
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This means that the variable context for the command consists of
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global variables only (it ignores any Tcl procedure that is active).
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This produces an effect similar to the Tcl command ``\fBuplevel 0\fR''.
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.PP
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During the processing of a Tcl command it is legal to make nested
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calls to evaluate other commands (this is how procedures and
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some control structures are implemented).
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If a code other than \fBTCL_OK\fR is returned
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from a nested \fBTcl_EvalObj\fR invocation,
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then the caller should normally return immediately,
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passing that same return code back to its caller,
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and so on until the top-level application is reached.
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A few commands, like \fBfor\fR, will check for certain
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return codes, like \fBTCL_BREAK\fR and \fBTCL_CONTINUE\fR, and process them
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specially without returning.
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.PP
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\fBTcl_EvalObj\fR keeps track of how many nested \fBTcl_EvalObj\fR
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invocations are in progress for \fIinterp\fR.
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If a code of \fBTCL_RETURN\fR, \fBTCL_BREAK\fR, or \fBTCL_CONTINUE\fR is
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about to be returned from the topmost \fBTcl_EvalObj\fR
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invocation for \fIinterp\fR,
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it converts the return code to \fBTCL_ERROR\fR
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and sets the interpreter's result object
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to point to an error message indicating that
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the \fBreturn\fR, \fBbreak\fR, or \fBcontinue\fR command was
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invoked in an inappropriate place.
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This means that top-level applications should never see a return code
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from \fBTcl_EvalObj\fR other then \fBTCL_OK\fR or \fBTCL_ERROR\fR.
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.SH "SEE ALSO"
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Tcl_GetObjResult, Tcl_SetObjResult
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.SH KEYWORDS
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command, execute, file, global, object, object result, variable
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