path: root/doc/info.n

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'\" RCS: @(#) $Id: info.n,v 1.18 2006/11/28 22:20:27 andreas_kupries Exp $
'\" 
.so man.macros
.TH info n 8.4 Tcl "Tcl Built-In Commands"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
info \- Return information about the state of the Tcl interpreter
.SH SYNOPSIS
\fBinfo \fIoption \fR?\fIarg arg ...\fR?
.BE

.SH DESCRIPTION
.PP
This command provides information about various internals of the Tcl
interpreter.
The legal \fIoption\fR's (which may be abbreviated) are:
.TP
\fBinfo args \fIprocname\fR
Returns a list containing the names of the arguments to procedure
\fIprocname\fR, in order.  \fIProcname\fR must be the name of a
Tcl command procedure.
.TP
\fBinfo body \fIprocname\fR
Returns the body of procedure \fIprocname\fR.  \fIProcname\fR must be
the name of a Tcl command procedure.
.TP
\fBinfo cmdcount\fR
Returns a count of the total number of commands that have been invoked
in this interpreter.
.TP
\fBinfo commands \fR?\fIpattern\fR?
If \fIpattern\fR isn't specified,
'\" Do not move this .VS above the .TP
.VS 8.5
returns a list of names of all the Tcl commands visible
(i.e. executable without using a qualified name) to the current namespace,
including both the built-in commands written in C and
the command procedures defined using the \fBproc\fR command.
If \fIpattern\fR is specified,
only those names matching \fIpattern\fR are returned.
Matching is determined using the same rules as for \fBstring match\fR.
\fIpattern\fR can be a qualified name like \fBFoo::print*\fR.
That is, it may specify a particular namespace
using a sequence of namespace names separated by double colons (\fB::\fR),
and may have pattern matching special characters
at the end to specify a set of commands in that namespace.
If \fIpattern\fR is a qualified name,
the resulting list of command names has each one qualified with the name
of the specified namespace, and only the commands defined in the named
namespace are returned.
'\" Technically, most of this hasn't changed; that's mostly just the
'\" way it always worked. Hardly anyone knew that though.
.VE 8.5
.TP
\fBinfo complete \fIcommand\fR
Returns 1 if \fIcommand\fR is a complete Tcl command in the sense of
having no unclosed quotes, braces, brackets or array element names.
If the command doesn't appear to be complete then 0 is returned.
This command is typically used in line-oriented input environments
to allow users to type in commands that span multiple lines;  if the
command isn't complete, the script can delay evaluating it until additional
lines have been typed to complete the command.
.TP
\fBinfo default \fIprocname arg varname\fR
\fIProcname\fR must be the name of a Tcl command procedure and \fIarg\fR
must be the name of an argument to that procedure.  If \fIarg\fR
doesn't have a default value then the command returns \fB0\fR.
Otherwise it returns \fB1\fR and places the default value of \fIarg\fR
into variable \fIvarname\fR.
.TP
\fBinfo exists \fIvarName\fR
Returns \fB1\fR if the variable named \fIvarName\fR exists in the
current context (either as a global or local variable) and has been
defined by being given a value, returns \fB0\fR otherwise.

.TP
\fBinfo frame\fR ?\fInumber\fR?
This command provides access to all frames on the stack, even those
hidden from \fBinfo level\fR. If \fInumber\fR is not specified, this
command returns a number giving the frame level of the command. This
is 1 if the command is invoked at top-level. If \fInumber\fR is
specified, then the result is a dictionary containing the location
information for the command at the \fInumber\fRed level on the stack.
.sp
If \fInumber\fR is positive (> 0) then it selects a particular stack
level (1 refers to the top-most active command, i.e., \fBinfo frame\fR
itself, 2 to the command it was called from, and so on); otherwise it
gives a level relative to the current command (0 refers to the current
command, i.e., \fBinfo frame\fR itself, -1 to its caller, and so on).
.sp
This is similar to how \fBinfo level\fR works, except that this
subcommand reports all frames, like \fBsource\fR'd scripts,
\fBeval\fR's, \fBuplevel\fR's, etc.
.sp
Note that for nested commands, like "foo [[bar [[x]]]]" only "x" will
be seen by an \fBinfo frame\fR invoked within "x". This is the same as
for \fBinfo level\fR and error stack traces.
.sp
The result dictionary may contain the keys listed below, with the
specified meanings for their values:
.RS
.TP
\fItype\fR
This entry is always present and describes the nature of the location
for the command. The recognized values are \fBsource\fR, \fBproc\fR,
\fBeval\fR, and \fBprecompiled\fR.
.RS
.TP
\fBsource\fR
means that the command is found in a script loaded by the \fBsource\fR
command.
.TP
\fBproc\fR
means that the command is found in dynamically created procedure body.
.TP
\fBeval\fR
means that the command is executed by \fBeval\fR or \fBuplevel\fR.
.TP
\fBprecompiled\fR
means that the command is found in a precompiled script (loadable by
the package \fBtbcload\fR), and no further information will be
available.
.RE
.TP
\fIline\fR
This entry provides the number of the line the command is at inside of
the script it is a part of. This information is not present for type
\fBprecompiled\fR. For type \fBsource\fR this information is counted
relative to the beginning of the file, whereas for the last two types
the line is counted relative to the start of the script.
.TP
\fIfile\fR
This entry is present only for type \fBsource\fR. It provides the
normalized path of the file the command is in.
.TP
\fIcmd\fR
This entry provides the string representation of the command. This is
usually the unsubstituted form, however for commands which are a pure
list executed by eval it is the substituted form as they have no other
string representation. Care is taken that the pure-List property of
the latter is not spoiled.
.TP
\fIproc\fR
This entry is present only if the command is found in the body of a
regular Tcl procedure. It then provides the name of that procedure.
.TP
\fIlambda\fR
This entry is present only if the command is found in the body of an
anonymous Tcl procedure, i.e. a lambda. It then provides the entire
definition of the lambda in question.
.TP
\fIlevel\fR
This entry is present only if the queried frame has a corresponding
frame returned by \fBinfo level\fR. It provides the index of this
frame, relative to the current level (0 and negative numbers).
.RE
.sp
.RS
A thing of note is that for procedures statically defined in files the
locations of commands in their bodies will be reported with type
\fBsource\fR and absolute line numbers, and not as type
\fBproc\fR. The same is true for procedures nested in statically
defined procedures, and literal eval scripts in files or statically
defined procedures.
.sp
In contrast, a procedure definition or \fBeval\fR within a dynamically
\fBeval\fRuated environment count linenumbers relative to the start of
their script, even if they would be able to count relative to the
start of the outer dynamic script. That type of number usually makes
more sense.
.sp
A different way of describing this behaviour is that file based
locations are tracked as deeply as possible, and where this is not
possible the lines are counted based on the smallest possible
\fBeval\fR or procedure body, as that scope is usually easier to find
than any dynamic outer scope.
.sp
The syntactic form \fB{expand}\fR is handled like \fBeval\fR. I.e. if it
is given a literal list argument the system tracks the linenumber
within the list words as well, and otherwise all linenumbers are
counted relative to the start of each word (smallest scope)
.RE
.TP
\fBinfo functions \fR?\fIpattern\fR?
If \fIpattern\fR isn't specified, returns a list of all the math
functions currently defined.
If \fIpattern\fR is specified, only those functions whose name matches
\fIpattern\fR are returned.  Matching is determined using the same
rules as for \fBstring match\fR.
.TP
\fBinfo globals \fR?\fIpattern\fR?
If \fIpattern\fR isn't specified, returns a list of all the names
of currently-defined global variables.
Global variables are variables in the global namespace.
If \fIpattern\fR is specified, only those names matching \fIpattern\fR
are returned.  Matching is determined using the same rules as for
\fBstring match\fR.
.TP
\fBinfo hostname\fR
Returns the name of the computer on which this invocation is being
executed.
Note that this name is not guaranteed to be the fully qualified domain
name of the host.  Where machines have several different names (as is
common on systems with both TCP/IP (DNS) and NetBIOS-based networking
installed,) it is the name that is suitable for TCP/IP networking that
is returned.
.TP
\fBinfo level\fR ?\fInumber\fR?
If \fInumber\fR is not specified, this command returns a number
giving the stack level of the invoking procedure, or 0 if the
command is invoked at top-level.  If \fInumber\fR is specified,
then the result is a list consisting of the name and arguments for the
procedure call at level \fInumber\fR on the stack.  If \fInumber\fR
is positive then it selects a particular stack level (1 refers
to the top-most active procedure, 2 to the procedure it called, and
so on); otherwise it gives a level relative to the current level
(0 refers to the current procedure, -1 to its caller, and so on).
See the \fBuplevel\fR command for more information on what stack
levels mean.
.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.
See the \fBtclvars\fR manual entry for more information.
.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
the package.
For statically-loaded packages the file name will be an empty string.
If \fIinterp\fR is omitted then information is returned for all packages
loaded in any interpreter in the process.
To get a list of just the packages in the current interpreter, specify
an empty string for the \fIinterp\fR argument.
.TP
\fBinfo locals \fR?\fIpattern\fR?
If \fIpattern\fR isn't specified, returns a list of all the names
of currently-defined local variables, including arguments to the
current procedure, if any.
Variables defined with the \fBglobal\fR, \fBupvar\fR  and
\fBvariable\fR commands will not be returned.
If \fIpattern\fR is specified, only those names matching \fIpattern\fR
are returned.  Matching is determined using the same rules as for
\fBstring match\fR.
.TP
\fBinfo nameofexecutable\fR
Returns the full path name of the binary file from which the application
was invoked.  If Tcl was unable to identify the file, then an empty
string is returned.
.TP
\fBinfo patchlevel\fR
Returns the value of the global variable \fBtcl_patchLevel\fR; see
the \fBtclvars\fR manual entry for more information.
.TP
\fBinfo procs \fR?\fIpattern\fR?
If \fIpattern\fR isn't 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
matching \fIpattern\fR are returned.
Matching is determined using the same rules as for
\fBstring match\fR.
If \fIpattern\fR contains any namespace separators, they are used to
select a namespace relative to the current namespace (or relative to
the global namespace if \fIpattern\fR starts with \fB::\fR) to match
within; the matching pattern is taken to be the part after the last
namespace separator.
.TP
\fBinfo script\fR ?\fIfilename\fR?
If a Tcl script file is currently being evaluated (i.e. there is a
call to \fBTcl_EvalFile\fR active or there is an active invocation
of the \fBsource\fR command), then this command returns the name
of the innermost file being processed.  If \fIfilename\fR is specified,
then the return value of this command will be modified for the
duration of the active invocation to return that name.  This is
useful in virtual file system applications.
Otherwise the command returns an empty string.
.TP
\fBinfo sharedlibextension\fR
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 aren't supported on this platform then an empty
string is returned.
.TP
\fBinfo tclversion\fR
Returns the value of the global variable \fBtcl_version\fR; see
the \fBtclvars\fR manual entry for more information.
.TP
\fBinfo vars\fR ?\fIpattern\fR?
If \fIpattern\fR isn't 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
are returned.  Matching is determined using the same rules as for
\fBstring match\fR.
\fIpattern\fR can be a qualified name like \fBFoo::option*\fR.
That is, it may specify a particular namespace
using a sequence of namespace names separated by double colons (\fB::\fR),
and may have pattern matching special characters
at the end to specify a set of variables in that namespace.
If \fIpattern\fR is a qualified name,
the resulting list of variable names
has each matching namespace variable qualified with the name
of its namespace.
Note that a currently-visible variable may not yet "exist" if it has not
been set (e.g. a variable declared but not set by \fBvariable\fR).
.SH EXAMPLE
This command prints out a procedure suitable for saving in a Tcl
script:
.CS
proc printProc {procName} {
    set result [list proc $procName]
    set formals {}
    foreach var [\fBinfo args\fR $procName] {
        if {[\fBinfo default\fR $procName $var def]} {
            lappend formals [list $var $def]
        } else {
            # Still need the list-quoting because variable
            # names may properly contain spaces.
            lappend formals [list $var]
        }
    }
    puts [lappend result $formals [\fBinfo body\fR $procName]]
}
.CE

.SH "SEE ALSO"
global(n), proc(n)

.SH KEYWORDS
command, information, interpreter, level, namespace, procedure, variable

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