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'\" RCS: @(#) $Id: info.n,v 1.19 2007/07/04 13:51:29 dkf Exp $
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.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

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

.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\0\0\0\0\0\0\0\0
means that the command is found in a script loaded by the \fBsource\fR
command.
.TP
\fBproc\fR\0\0\0\0\0\0\0\0
means that the command is found in dynamically created procedure body.
.TP
\fBeval\fR\0\0\0\0\0\0\0\0
means that the command is executed by \fBeval\fR or \fBuplevel\fR.
.TP
\fBprecompiled\fR\0\0\0\0\0\0\0\0
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

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).
.PP


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.
.PP
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.
.PP
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.
.PP
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?

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:
.PP
.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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