107 lines
4.0 KiB
Groff
107 lines
4.0 KiB
Groff
'\"
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'\" Copyright (c) 1989-1993 The Regents of the University of California.
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'\" Copyright (c) 1994-1996 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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'\" SCCS: @(#) Eval.3 1.17 96/03/25 20:02:33
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'\"
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.so man.macros
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.TH Tcl_Eval 3 7.0 Tcl "Tcl Library Procedures"
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.BS
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.SH NAME
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Tcl_Eval, Tcl_VarEval, Tcl_EvalFile, Tcl_GlobalEval \- execute Tcl commands
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.SH SYNOPSIS
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.nf
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\fB#include <tcl.h>\fR
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.sp
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int
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.VS
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\fBTcl_Eval\fR(\fIinterp, cmd\fR)
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.VE
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.sp
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int
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\fBTcl_VarEval\fR(\fIinterp, string, string, ... \fB(char *) NULL\fR)
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.sp
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int
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\fBTcl_EvalFile\fR(\fIinterp, fileName\fR)
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.sp
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int
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\fBTcl_GlobalEval\fR(\fIinterp, cmd\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. String result will be
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stored in \fIinterp->result\fR.
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.AP char *cmd in
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Command (or sequence of commands) to execute. Must be in writable
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memory (\fBTcl_Eval\fR makes temporary modifications to the command).
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.AP char *string in
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String forming part of Tcl command.
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.AP char *fileName in
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Name of file containing Tcl command string.
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.BE
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.SH DESCRIPTION
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.PP
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All four of these procedures execute Tcl commands.
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\fBTcl_Eval\fR is the core procedure: it parses commands
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from \fIcmd\fR and executes them in
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.VS
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order until either an error occurs or it reaches the end of the string.
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.VE
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The return value from \fBTcl_Eval\fR is one
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of the Tcl return codes \fBTCL_OK\fR, \fBTCL_ERROR\fR, \fBTCL_RETURN\fR, \fBTCL_BREAK\fR, or
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\fBTCL_CONTINUE\fR, and \fIinterp->result\fR will point to
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a string with additional information (result value or error message).
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This return information corresponds to the last command executed from
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\fIcmd\fR.
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.PP
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\fBTcl_VarEval\fR takes any number of string arguments
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of any length, concatenates
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them into a single string, then calls \fBTcl_Eval\fR to
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execute that string as a Tcl command.
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It returns the result of the command and also modifies
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\fIinterp->result\fR in the usual fashion for Tcl commands. The
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last argument to \fBTcl_VarEval\fR must be NULL to indicate the end
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of arguments.
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.PP
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\fBTcl_EvalFile\fR reads the file given by \fIfileName\fR and evaluates
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its contents as a Tcl command by calling \fBTcl_Eval\fR. It returns
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a standard Tcl result that reflects the result of evaluating the
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file.
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If the file couldn't be read then a Tcl error is returned to describe
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why the file couldn't be read.
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.PP
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\fBTcl_GlobalEval\fR is similar to \fBTcl_Eval\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 conditionals, loops,
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and procedures are implemented).
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If a code other than
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\fBTCL_OK\fR is returned from a nested \fBTcl_Eval\fR invocation, then the
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caller should normally return immediately, passing that same
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return code back to its caller, and so on until the top-level application is
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reached. 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_Eval\fR keeps track of how many nested Tcl_Eval invocations are
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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_Eval\fR invocation for
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\fIinterp\fR, then \fBTcl_Eval\fR converts the return code to \fBTCL_ERROR\fR
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and sets \fIinterp->result\fR 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. This means that top-level
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applications should never see a return code from \fBTcl_Eval\fR other then
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\fBTCL_OK\fR or \fBTCL_ERROR\fR.
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.SH KEYWORDS
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command, execute, file, global, interpreter, variable
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