Tcl Source Code

'\"
'\" Copyright (c) 1996-1997 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: CrtChannel.3,v 1.1.2.3 1999/04/13 00:01:57 surles Exp $
.so man.macros
.TH Tcl_CreateChannel 3 8.0 Tcl "Tcl Library Procedures"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
Tcl_CreateChannel, Tcl_GetChannelInstanceData, Tcl_GetChannelType, Tcl_GetChannelName, Tcl_GetChannelHandle, Tcl_GetChannelMode, Tcl_GetChannelBufferSize, Tcl_SetChannelBufferSize, Tcl_NotifyChannel, Tcl_BadChannelOption \- procedures for creating and manipulating channels
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
Tcl_Channel
\fBTcl_CreateChannel\fR(\fItypePtr, channelName, instanceData, mask\fR)
.sp

\fBTcl_GetChannelName\fR(\fIchannel\fR)
.VS
.sp
int
\fBTcl_GetChannelHandle\fR(\fIchannel, direction, handlePtr\fR)
.VE
.sp





int
\fBTcl_GetChannelBufferSize\fR(\fIchannel\fR)
.sp
\fBTcl_SetChannelBufferSize\fR(\fIchannel, size\fR)
.sp
.VS
\fBTcl_NotifyChannel\fR(\fIchannel, mask\fR)

for each driver to determine what type of handle is returned.
.VE
.PP
\fBTcl_GetChannelMode\fR returns an OR-ed combination of \fBTCL_READABLE\fR
and \fBTCL_WRITABLE\fR, indicating whether the channel is open for input
and output.
.PP






 \fBTcl_GetChannelBufferSize\fR returns the size, in bytes, of buffers
allocated to store input or output in \fIchan\fR. If the value was not set
by a previous call to \fBTcl_SetChannelBufferSize\fR, described below, then
the default value of 4096 is returned.
.PP
\fBTcl_SetChannelBufferSize\fR sets the size, in bytes, of buffers that
will be allocated in subsequent operations on the channel to store input or
output. The \fIsize\fR argument should be between ten and one million,

	long \fIoffset\fR,
	int \fIseekMode\fR,
	int *\fIerrorCodePtr\fR);
.CE
.PP
The \fIinstanceData\fR argument is the same as the value given to
\fBTcl_CreateChannel\fR when this channel was created.  \fIOffset\fR and
\fIseekMode\fR have the same meaning as for the \fBTcl_Seek\fR
procedure (described in the manual entry for \fBTcl_OpenFileChannel\fR).
.PP
The \fIerrorCodePtr\fR argument points to an integer variable provided by
the generic layer for returning \fBerrno\fR values from the function.  The
function should set this variable to a POSIX error code if an error occurs.
The function should store an \fBEINVAL\fR error code if the channel type
does not implement seeking.

'\"
'\" Copyright (c) 1996-1997 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: CrtObjCmd.3,v 1.1.2.3 1999/04/13 00:01:57 surles Exp $
'\" 
.so man.macros
.TH Tcl_CreateObjCommand 3 8.0 Tcl "Tcl Library Procedures"
.BS
.SH NAME
Tcl_CreateObjCommand, Tcl_DeleteCommand, Tcl_DeleteCommandFromToken, Tcl_GetCommandInfo, Tcl_SetCommandInfo, Tcl_GetCommandName \- implement new commands in C
.SH SYNOPSIS

of the \fIobjv\fR array by assigning new pointer values to any element of the
array (for example, \fIobjv\fR[\fB2\fR] = \fBNULL\fR) because this will
cause memory to be lost and the runtime stack to be corrupted.  The
\fBCONST\fR in the declaration of \fIobjv\fR will cause ANSI-compliant
compilers to report any such attempted assignment as an error.  However,
it is acceptable to modify the internal representation of any individual
object argument.  For instance, the user may call
\fBTcl_GetIntFromObj\fR on \fIobjv\fR[\fB2\fR] to obtain the integer
representation of that object; that call may change the type of the object
that \fIobjv\fR[\fB2\fR] points at, but will not change where
\fIobjv\fR[\fB2\fR] points.
.VE
.PP
\fIproc\fR must return an integer code that is either \fBTCL_OK\fR,
\fBTCL_ERROR\fR, \fBTCL_RETURN\fR, \fBTCL_BREAK\fR, or \fBTCL_CONTINUE\fR.

'\"
'\" Copyright (c) 1997-1998 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: Encoding.3,v 1.1.2.5 1999/04/13 00:01:57 surles Exp $
'\" 
.so man.macros
.TH Tcl_GetEncoding 3 "8.1" Tcl "Tcl Library Procedures"
.BS
.SH NAME
Tcl_GetEncoding, Tcl_FreeEncoding, Tcl_ExternalToUtfDString, Tcl_ExternalToUtf, Tcl_UtfToExternalDString, Tcl_UtfToExternal, Tcl_GetEncodingName, Tcl_SetSystemEncoding, Tcl_GetEncodingNames, Tcl_CreateEncoding, Tcl_GetDefaultEncodingDir, Tcl_SetDefaultEncodingDir \- procedures for creating and using encodings.




.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
Tcl_Encoding
\fBTcl_GetEncoding\fR(\fIinterp, name\fR)
.sp

procedure increments the reference count of the new system encoding,
decrements the reference count of the old system encoding, and returns
TCL_OK.
.PP
\fBTcl_GetEncodingNames\fR sets the \fIinterp\fR result to a list
consisting of the names of all the encodings that are currently defined
or can be dynamically loaded, searching the encoding path specified by
\fBTcl_SetDefaultEncodingDir\fR.  This procedure does not ensure that the
dynamically-loadable encoding files contain valid data, but merely that they
exist.
.PP
\fBTcl_CreateEncoding\fR defines a new encoding and registers the C
procedures that are called back to convert between the encoding and
UTF-8.  Encodings created by \fBTcl_CreateEncoding\fR are thereafter
visible in the database used by \fBTcl_GetEncoding\fR.  Just as with the
\fBTcl_GetEncoding\fR procedure, the return value is a token that
represents the encoding and can be used in subsequent calls to other
encoding functions.  \fBTcl_CreateEncoding\fR returns an encoding with a
reference count of 1. If an encoding with the specified \fIname\fR
already exists, then its entry in the database is replaced with the new
encoding; the token for the old encoding will remain valid and continue

'\"
'\" Copyright (c) 1996-1997 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: Object.3,v 1.1.2.3 1999/04/13 00:01:58 surles Exp $
'\" 
.so man.macros
.TH Tcl_Obj 3 8.0 Tcl "Tcl Library Procedures"
.BS
.SH NAME
Tcl_NewObj, Tcl_DuplicateObj, Tcl_IncrRefCount, Tcl_DecrRefCount, Tcl_IsShared \- manipulate Tcl objects
.SH SYNOPSIS

The procedure \fBTcl_InvalidateStringRep\fR is used
to mark an object's string representation invalid and to
free any storage associated with the old string representation.
.PP
Objects usually remain one type over their life,
but occasionally an object must be converted from one type to another.
For example, a C program might build up a string in an object
with repeated calls to \fBTcl_ObjAppend\fR,
and then call \fBTcl_ListObjIndex\fR to extract a list element from
the object.
The same object holding the same string value
can have several different internal representations
at different times.
Extension writers can also force an object to be converted from one type
to another using the \fBTcl_ConvertToType\fR procedure.

'\"
'\" 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: SetRecLmt.3,v 1.1.2.2 1999/04/13 00:01:59 surles Exp $
'\" 
.so man.macros
.TH Tcl_SetRecursionLimit 3 7.0 Tcl "Tcl Library Procedures"
.BS
.SH NAME
Tcl_SetRecursionLimit \- set maximum allowable nesting depth in interpreter
.SH SYNOPSIS

By default the recursion limit is 1000.
.PP
\fBTcl_SetRecursionLimit\fR may be used to change the maximum
allowable nesting depth for an interpreter.
The \fIdepth\fR argument specifies a new limit for \fIinterp\fR,
and \fBTcl_SetRecursionLimit\fR returns the old limit.
To read out the old limit without modifying it, invoke
\fBTcl_SetRecursionLimit\fR with \fIdepth\fR equal to 0.
.PP
The \fBTcl_SetRecursionLimit\fR only sets the size of the Tcl
call stack:  it cannot by itself prevent stack overflows on the
C stack being used by the application.  If your machine has a
limit on the size of the C stack, you may get stack overflows
before reaching the limit set by \fBTcl_SetRecursionLimit\fR.
If this happens, see if there is a mechanism in your system for
increasing the maximum size of the C stack.

.SH KEYWORDS
nesting depth, recursion

'\"
'\" Copyright (c) 1993-1994 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: catch.n,v 1.1.2.3 1999/04/13 00:01:59 surles Exp $
'\" 
.so man.macros
.TH catch n "8.0" Tcl "Tcl Built-In Commands"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
catch \- Evaluate script and trap exceptional returns

given, then the variable it names is set to the error message from
interpreting \fIscript\fR.
.PP
If \fIscript\fR does not raise an error, \fBcatch\fR will return 0
(TCL_OK) and set the variable to the value returned from \fIscript\fR.
.PP
Note that \fBcatch\fR catches all exceptions, including those
generated by \fBbreak\fR and \fBcontinue\fR as well as errors.  The
only errors that are not caught are syntax errors found when the
script is compiled.  This is because the catch command only catches
errors during runtime.  When the catch statement is compiled, the
script is compiled as well and any syntax errors will generate a Tcl
error. 

.SH EXAMPLES

The \fBcatch\fR command may be used in an \fBif\fR to branch based on
the success of a script.

.DS
.CS
if { [catch {open $someFile w} fid] } {
    puts stderr "Could not open $someFile for writing\\n$fid"
    exit 1
}
.CE
.DE
The \fBcatch\fR command will not catch compiled syntax errors.  The
first time proc \fBfoo\fR is called, the body will be compiled and a
Tcl error will be generated. 

.DS
.CS
proc foo {} {
    catch {expr {1 +- }}
}
.CE
.DE

.SH KEYWORDS
catch, error