'\"
'\" Copyright (c) 1994 The Regents of the University of California.
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
'\" Copyright (c) 2000 Ajuba Solutions.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
.TH Tcl_Main 3tcl 9.0 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)
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.\"	name are examples of largest possible arguments that will be passed
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.\" .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?
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.\"
.\" .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
..
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.\"	# ^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
..
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.\"	# 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
..
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.de CS
.RS
.nf
.ta .25i .5i .75i 1i
..
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.de CE
.fi
.RE
..
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.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_Main, Tcl_MainEx, Tcl_MainExW, Tcl_SetStartupScript, Tcl_GetStartupScript, Tcl_SetMainLoop \- main program, startup script, and event loop definition for Tcl-based applications
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
\fBTcl_Main\fR(\fIargc, argv, appInitProc\fR)
.sp
\fBTcl_MainEx\fR(\fIargc, charargv, appInitProc, interp\fR)
.sp
\fBTcl_MainExW\fR(\fIargc, wideargv, appInitProc, interp\fR)
.sp
\fBTcl_SetStartupScript\fR(\fIpath, encoding\fR)
.sp
Tcl_Obj *
\fBTcl_GetStartupScript\fR(\fIencodingPtr\fR)
.sp
\fBTcl_SetMainLoop\fR(\fImainLoopProc\fR)
.SH ARGUMENTS
.AS Tcl_MainLoopProc *mainLoopProc
.AP Tcl_Size argc in
Number of elements in \fIargv\fR.
.AP char *argv[] in
Array of strings containing command-line arguments. On Windows, when
using -DUNICODE, the parameter type changes to wchar_t *.
.AP char *charargv[] in
As argv, but does not change type to wchar_t.
.AP char *wideargv[] in
As argv, but type is always wchar_t.
.AP Tcl_AppInitProc *appInitProc in
Address of an application-specific initialization procedure.
The value for this argument is usually \fBTcl_AppInit\fR.
.AP Tcl_Obj *path in
Name of file to use as startup script, or NULL.
.AP "const char" *encoding in
Encoding of file to use as startup script, or NULL.
.AP "const char" **encodingPtr out
If non-NULL, location to write a copy of the (const char *)
pointing to the encoding name.
.AP Tcl_MainLoopProc *mainLoopProc in
Address of an application-specific event loop procedure.
.AP Tcl_Interp *interp in
Already created Tcl Interpreter.
.BE
.SH DESCRIPTION
.PP
\fBTcl_Main\fR can serve as the main program for Tcl-based shell
applications.  A
.QW "shell application"
is a program
like tclsh or wish that supports both interactive interpretation
of Tcl and evaluation of a script contained in a file given as
a command line argument.  \fBTcl_Main\fR is offered as a convenience
to developers of shell applications, so they do not have to
reproduce all of the code for proper initialization of the Tcl
library and interactive shell operation.  Other styles of embedding
Tcl in an application are not supported by \fBTcl_Main\fR.  Those
must be achieved by calling lower level functions in the Tcl library
directly.
.PP
The \fBTcl_Main\fR function has been offered by the Tcl library
since release Tcl 7.4.  In older releases of Tcl, the Tcl library
itself defined a function \fBmain\fR, but that lacks flexibility
of embedding style and having a function \fBmain\fR in a library
(particularly a shared library) causes problems on many systems.
Having \fBmain\fR in the Tcl library would also make it hard to use
Tcl in C++ programs, since C++ programs must have special C++
\fBmain\fR functions.
.PP
Normally each shell application contains a small \fBmain\fR function
that does nothing but invoke \fBTcl_Main\fR.
\fBTcl_Main\fR then does all the work of creating and running a
\fBtclsh\fR-like application.
.PP
\fBTcl_Main\fR is not provided by the public interface of Tcl's
stub library.  Programs that call \fBTcl_Main\fR must be linked
against the standard Tcl library.  If the standard Tcl library is
a dll (so, not a static .lib/.a) , then the program must be linked
against the stub library as well. Extensions
(stub-enabled or not) are not intended to call \fBTcl_Main\fR.
.PP
\fBTcl_Main\fR is not thread-safe.  It should only be called by
a single main thread of a multi-threaded application.  This
restriction is not a problem with normal use described above.
.PP
\fBTcl_Main\fR and therefore all applications based upon it, like
\fBtclsh\fR, use \fBTcl_GetStdChannel\fR to initialize the standard
channels to their default values. See \fBTcl_StandardChannels\fR for
more information.
.PP
\fBTcl_Main\fR supports two modes of operation, depending on
whether the filename and encoding of a startup script has been
established.  The routines \fBTcl_SetStartupScript\fR and
\fBTcl_GetStartupScript\fR are the tools for controlling this
configuration of \fBTcl_Main\fR.
.PP
\fBTcl_SetStartupScript\fR registers the value \fIpath\fR
as the name of the file for \fBTcl_Main\fR to evaluate as
its startup script.  The value \fIencoding\fR is Tcl's name
for the encoding used to store the text in that file.  A
value of \fBNULL\fR for \fIencoding\fR is a signal to use
the system encoding.  A value of \fBNULL\fR for \fIpath\fR
erases any existing registration so that \fBTcl_Main\fR
will not evaluate any startup script.
.PP
\fBTcl_GetStartupScript\fR queries the registered file name
and encoding set by the most recent \fBTcl_SetStartupScript\fR
call in the same thread.  The stored file name is returned,
and the stored encoding name is written to space pointed to
by \fIencodingPtr\fR, when that is not NULL.
.PP
The file name and encoding values managed by the routines
\fBTcl_SetStartupScript\fR and \fBTcl_GetStartupScript\fR
are stored per-thread.  Although the storage and retrieval
functions of these routines work in any thread, only those
calls in the same main thread as \fBTcl_Main\fR can have
any influence on it.
.PP
The caller of \fBTcl_Main\fR may call \fBTcl_SetStartupScript\fR
first to establish its desired startup script.  If \fBTcl_Main\fR
finds that no such startup script has been established, it consults
the first few arguments in \fIargv\fR.  If they match
?\fB\-encoding \fIname\fR? \fIfileName\fR,
where \fIfileName\fR does not begin with the character \fI\-\fR,
then \fIfileName\fR is taken to be the name of a file containing
a \fIstartup script\fR, and \fIname\fR is taken to be the name
of the encoding of the contents of that file.  \fBTcl_Main\fR
then calls \fBTcl_SetStartupScript\fR with these values.
.PP
\fBTcl_Main\fR then defines in its main interpreter
the Tcl variables \fIargc\fR, \fIargv\fR, \fIargv0\fR, and
\fItcl_interactive\fR, as described in the documentation for \fBtclsh\fR.
.PP
When it has finished its own initialization, but before it processes
commands, \fBTcl_Main\fR calls the procedure given by the
\fIappInitProc\fR argument.  This procedure provides a
.QW hook
for the application to perform its own initialization of the interpreter
created by \fBTcl_Main\fR, such as defining application-specific
commands.  The application initialization routine might also
call \fBTcl_SetStartupScript\fR to (re-)set the file and encoding
to be used as a startup script.  The procedure must have an interface
that matches the type \fBTcl_AppInitProc\fR:
.PP
.CS
typedef int \fBTcl_AppInitProc\fR(
        Tcl_Interp *\fIinterp\fR);
.CE
.PP
\fIAppInitProc\fR is almost always a pointer to \fBTcl_AppInit\fR; for more
details on this procedure, see the documentation for \fBTcl_AppInit\fR.
.PP
When the \fIappInitProc\fR is finished, \fBTcl_Main\fR calls
\fBTcl_GetStartupScript\fR to determine what startup script has
been requested, if any.  If a startup script has been provided,
\fBTcl_Main\fR attempts to evaluate it.  Otherwise, interactive
mode begins with examination of the variable \fItcl_rcFileName\fR
in the main interpreter.  If that variable exists and holds the
name of a readable file, the contents of that file are evaluated
in the main interpreter.  Then interactive operations begin,
with prompts and command evaluation results written to the standard
output channel, and commands read from the standard input channel
and then evaluated.  The prompts written to the standard output
channel may be customized by defining the Tcl variables \fItcl_prompt1\fR
and \fItcl_prompt2\fR as described in the documentation for \fBtclsh\fR.
The prompts and command evaluation results are written to the standard
output channel only if the Tcl variable \fItcl_interactive\fR in the
main interpreter holds a non-zero integer value.
.PP
\fBTcl_SetMainLoop\fR allows setting an event loop procedure to be run.
This allows, for example, Tk to be dynamically loaded and set its event
loop.  The event loop will run following the startup script.  If you
are in interactive mode, setting the main loop procedure will cause the
prompt to become fileevent based and then the loop procedure is called.
When the loop procedure returns in interactive mode, interactive operation
will continue.
The main loop procedure must have an interface that matches the type
\fBTcl_MainLoopProc\fR:
.PP
.CS
typedef void \fBTcl_MainLoopProc\fR(void);
.CE
.PP
\fBTcl_Main\fR does not return.  Normally a program based on
\fBTcl_Main\fR will terminate when the \fBexit\fR command is
evaluated.  In interactive mode, if an EOF or channel error
is encountered on the standard input channel, then \fBTcl_Main\fR
itself will evaluate the \fBexit\fR command after the main loop
procedure (if any) returns.  In non-interactive mode, after
\fBTcl_Main\fR evaluates the startup script, and the main loop
procedure (if any) returns, \fBTcl_Main\fR will also evaluate
the \fBexit\fR command.
.PP
\fBTcl_Main\fR can not be used in stub-enabled extensions.
.PP
The difference between Tcl_MainEx and Tcl_MainExW is that the arguments
are passed as characters or wide characters. When used in stub-enabled
embedders, the stubs table must be first initialized using one of
\fBTcl_InitSubsystems\fR, \fBTcl_SetPanicProc\fR, \fBTcl_FindExecutable\fR or \fBTclZipfs_AppHook\fR.
.SH "REFERENCE COUNT MANAGEMENT"
.PP
\fBTcl_SetStartupScript\fR takes a value (or NULL) for its \fIpath\fR
argument, and will increment the reference count of it.
.PP
\fBTcl_GetStartupScript\fR returns a value with reference count at least 1, or
NULL. It's \fIencodingPtr\fR is also used (if non-NULL) to return a value with
a reference count at least 1, or NULL. In both cases, the owner of the values
is the current thread.
.SH "SEE ALSO"
tclsh(1), Tcl_GetStdChannel(3tcl), Tcl_StandardChannels(3tcl), Tcl_AppInit(3tcl),
exit(3tcl), encoding(3tcl)
.SH KEYWORDS
application-specific initialization, command-line arguments, main program