Tcl Source Code

the stack trace text they append to the \fB\-errorinfo\fR option.
Tcl provides several simpler interfaces to more directly set
these return options.
.PP
The \fB\-errorinfo\fR option holds a stack trace of the
operations that were in progress when an error occurred,
and is intended to be human-readable.
The \fB\-errorcode\fR option holds a Tcl list of items that
are intended to be machine-readable.
The first item in the \fB\-errorcode\fR value identifies the class of
error that occurred
(e.g., POSIX means an error occurred in a POSIX system call)
and additional elements hold additional pieces
of information that depend on the class.
See the manual entry on the \fBerrorCode\fR variable for details on the
various formats for the \fB\-errorcode\fR option used by Tcl's built-in
commands.
.PP
The \fB\-errorinfo\fR option value is gradually built up as an
error unwinds through the nested operations.
Each time an error code is returned to \fBTcl_Eval\fR, or
any of the routines that performs script evaluation,
the procedure \fBTcl_AddErrorInfo\fR is called to add
additional text to the \fB\-errorinfo\fR value describing the

occurred after all.
The global variables \fBerrorInfo\fR and
\fBerrorCode\fR are not modified by \fBTcl_ResetResult\fR
so they continue to hold a record of information about the
most recent error seen in an interpreter.
.SH "SEE ALSO"
Tcl_DecrRefCount(3), Tcl_IncrRefCount(3), Tcl_Interp(3), Tcl_ResetResult(3),
Tcl_SetErrno(3), errorCode(n), errorInfo(n)
.SH KEYWORDS
error, value, value result, stack, trace, variable

a token for it. The token is required in calls to most other Tcl
procedures, such as \fBTcl_CreateCommand\fR, \fBTcl_Eval\fR, and
\fBTcl_DeleteInterp\fR.  The token returned by \fBTcl_CreateInterp\fR
may only be passed to Tcl routines called from the same thread as
the original \fBTcl_CreateInterp\fR call.  It is not safe for multiple
threads to pass the same token to Tcl's routines.
The new interpreter is initialized with the built-in Tcl commands
and with standard variables like \fBtcl_platform\fR and \fBenv\fR. To
bind in additional commands, call \fBTcl_CreateCommand\fR, and to
create additional variables, call \fBTcl_SetVar\fR.
.PP
\fBTcl_DeleteInterp\fR marks an interpreter as deleted; the interpreter
will eventually be deleted when all calls to \fBTcl_Preserve\fR for it have
been matched by calls to \fBTcl_Release\fR. At that time, all of the
resources associated with it, including variables, procedures, and
application-specific command bindings, will be deleted. After
\fBTcl_DeleteInterp\fR returns any attempt to use \fBTcl_Eval\fR on the

.VS 8.6
Note that the protection mechanisms do not work well with conventional garbage
collection systems. When in such a managed environment, \fBTcl_InterpActive\fR
should be used to determine when an interpreter is a candidate for deletion
due to inactivity.
.VE 8.6
.SH "SEE ALSO"
Tcl_Preserve(3), Tcl_Release(3)
.SH KEYWORDS
command, create, delete, interpreter

.QW \fINAME\fB=\fIvalue\fR .
This procedure is
intended to be a stand-in for the UNIX \fBputenv\fR system call. All
Tcl-based applications using \fBputenv\fR should redefine it to
\fBTcl_PutEnv\fR so that they will interface properly to the Tcl
runtime.
.SH "SEE ALSO"
env(n)
.SH KEYWORDS
environment, variable

    set timestamp [clock format [clock seconds]]
    set fl [open mylog.txt {WRONLY CREAT APPEND}]
    puts $fl "$timestamp: bgerror in $::argv '$message'"
    close $fl
}
.CE
.SH "SEE ALSO"
after(n), errorCode(n), errorInfo(n), interp(n)
.SH KEYWORDS
background error, reporting
'\" Local Variables:
'\" mode: nroff
'\" End:

.CS
set f [open $filename rb]
set data [read $f]
close $f
puts [\fBbinary encode\fR base64 \-maxlen 64 $data]
.CE
.SH "SEE ALSO"
format(n), scan(n), tcl_platform(n)
.SH KEYWORDS
binary, format, scan
'\" Local Variables:
'\" mode: nroff
'\" End:

    exit 1
}
.CE
.PP
There are more complex examples of \fBcatch\fR usage in the
documentation for the \fBreturn\fR command.
.SH "SEE ALSO" 
break(n), continue(n), dict(n), error(n), errorCode(n), errorInfo(n), info(n),
return(n)
.SH KEYWORDS
catch, error, exception
'\" Local Variables:
'\" mode: nroff
'\" fill-column: 78
'\" End:

However, the last line would now normally be written without
\fBeval\fR, like this:
.PP
.CS
set var [linsert $var 0 {*}$args]
.CE
.SH "SEE ALSO"
catch(n), concat(n), error(n), errorCode(n), errorInfo(n), interp(n), list(n),
namespace(n), subst(n), uplevel(n)
.SH KEYWORDS
concatenate, evaluate, script
'\" Local Variables:
'\" mode: nroff
'\" End:

.TP
\fBinfo library\fR
.
Returns the name of the library directory in which standard Tcl
scripts are stored.
This is actually the value of the \fBtcl_library\fR
variable and may be changed by setting \fBtcl_library\fR.

.TP
\fBinfo loaded \fR?\fIinterp\fR?
.
Returns a list describing all of the packages that have been loaded into
\fIinterp\fR with the \fBload\fR command.
Each list element is a sub-list with two elements consisting of the
name of the file from which the package was loaded and the name of

.VS 8.6
Returns information about the object, \fIobject\fR. The \fIsubcommand\fRs are
described in \fBOBJECT INTROSPECTION\fR below.
.VE 8.6
.TP
\fBinfo patchlevel\fR
.
Returns the value of the global variable \fBtcl_patchLevel\fR, which holds
the exact version of the Tcl library by default.
.TP
\fBinfo procs \fR?\fIpattern\fR?
.
If \fIpattern\fR is not specified, returns a list of all the
names of Tcl command procedures in the current namespace.
If \fIpattern\fR is specified,
only those procedure names in the current namespace

Returns the extension used on this platform for the names of files
containing shared libraries (for example, \fB.so\fR under Solaris).
If shared libraries are not supported on this platform then an empty
string is returned.
.TP
\fBinfo tclversion\fR
.
Returns the value of the global variable \fBtcl_version\fR, which holds the
major and minor version of the Tcl library by default.
.TP
\fBinfo vars\fR ?\fIpattern\fR?
.
If \fIpattern\fR is not specified,
returns a list of all the names of currently-visible variables.
This includes locals and currently-visible globals.
If \fIpattern\fR is specified, only those names matching \fIpattern\fR

    # Assume no forwards
    return [\fBinfo class definition\fR $cls $method]
}
.CE
.VE 8.6
.SH "SEE ALSO"
.VS 8.6
global(n), oo::class(n), oo::define(n), oo::object(n), proc(n), self(n),
.VE 8.6
tcl_library(n), tcl_patchLevel(n), tcl_version(n)
.SH KEYWORDS
command, information, interpreter, introspection, level, namespace,
.VS 8.6
object,
.VE 8.6
procedure, variable
'\" Local Variables:
'\" mode: nroff
'\" fill-column: 78
'\" End:

any commands.
.TP
\fBauto_noload\fR
If set to any value, then \fBunknown\fR will not attempt to auto-load
any commands.
.TP
\fBauto_path\fR
.
If set, then it must contain a valid Tcl list giving directories to
search during auto-load operations (including for package index
files when using the default \fBpackage unknown\fR handler).
This variable is initialized during startup to contain, in order:
the directories listed in the \fBTCLLIBPATH\fR environment variable,
the directory named by the \fBtcl_library\fR global variable,
the parent directory of \fBtcl_library\fR,
the directories listed in the \fBtcl_pkgPath\fR variable.
Additional locations to look for files and package indices should
normally be added to this variable using \fBlappend\fR.
.TP
\fBenv(TCL_LIBRARY)\fR
If set, then it specifies the location of the directory containing
library scripts (the value of this variable will be
assigned to the \fBtcl_library\fR variable and therefore returned by
the command \fBinfo library\fR).  If this variable is not set then
a default value is used.

This variable contains a regular expression that is used by routines
like \fBtcl_endOfWord\fR to identify whether a character is part of a
word or not.  If the pattern matches a character, the character is
considered to be a word character.  On Windows platforms, words are
comprised of any character that is not a space, tab, or newline.  Under
Unix, words are comprised of numbers, letters or underscores.
.SH "SEE ALSO"
env(n), info(n), re_syntax(n)
.SH KEYWORDS
auto-exec, auto-load, library, unknown, word, whitespace 
'\"Local Variables:
'\"mode: nroff
'\"End:

    }
    set options [dict merge {-level 1} $args]
    dict incr options -level
    \fBreturn\fR -options $options $result
}
.CE
.SH "SEE ALSO"
break(n), catch(n), continue(n), dict(n), error(n), errorCode(n),
errorInfo(n), proc(n), source(n), throw(n), try(n)
.SH KEYWORDS
break, catch, continue, error, exception, procedure, result, return
.\" Local Variables:
.\" mode: nroff
.\" End:

You should note that it is also common practice to install tclsh with
its version number as part of the name.  This has the advantage of
allowing multiple versions of Tcl to exist on the same system at once,
but also the disadvantage of making it harder to write scripts that
start up uniformly across different versions of Tcl.
.SH "VARIABLES"
.PP
\fBTclsh\fR sets the following global Tcl variables in addition to those
created by the Tcl library itself (such as \fBenv\fR, which maps
environment variables such as \fBPATH\fR into Tcl):
.TP 15
\fBargc\fR
.
Contains a count of the number of \fIarg\fR arguments (0 if none),
not including the name of the script file.
.TP 15
\fBargv\fR

\fIfileName\fR was specified and standard input is a terminal-like
device), 0 otherwise.
.SH PROMPTS
.PP
When \fBtclsh\fR is invoked interactively it normally prompts for each
command with
.QW "\fB% \fR" .
You can change the prompt by setting the global
variables \fBtcl_prompt1\fR and \fBtcl_prompt2\fR.  If variable
\fBtcl_prompt1\fR exists then it must consist of a Tcl script
to output a prompt;  instead of outputting a prompt \fBtclsh\fR
will evaluate the script in \fBtcl_prompt1\fR.
The variable \fBtcl_prompt2\fR is used in a similar way when
a newline is typed but the current command is not yet complete;
if \fBtcl_prompt2\fR is not set then no prompt is output for
incomplete commands.
.SH "STANDARD CHANNELS"
.PP
See \fBTcl_StandardChannels\fR for more explanations.
.SH "SEE ALSO"
auto_path(n), encoding(n), env(n), fconfigure(n)
.SH KEYWORDS
application, argument, interpreter, prompt, script file, shell

The following produces an error that is identical to that produced by
\fBexpr\fR when trying to divide a value by zero.
.PP
.CS
\fBthrow\fR {ARITH DIVZERO {divide by zero}} {divide by zero}
.CE
.SH "SEE ALSO"
catch(n), error(n), errorCode(n), errorInfo(n), return(n), try(n)
.SH "KEYWORDS"
error, exception
'\" Local Variables:
'\" mode: nroff
'\" End: