TIP:            261
Title:          Return Imported Commands from [namespace import]
Version:        $Revision: 1.7 $
Author:         Martin Lemburg <martin.lemburg@gmx.net>
Author:         <dgp@users.sf.net>
State:          Final
Type:           Project
Vote:           Done
Created:        20-Dec-2005
Post-History:   
Tcl-Version:    8.5

~ Abstract

This TIP describes a mechanism for easily finding out the list of
commands in the current namespace that have been imported from other
namespaces.

~ Rationale

While writing a profiling and introspection module for our C++/Tcl
application, I searched for ways to query all the exported and
imported commands of a namespace.

Although I found the introspection functionality for discovering all
exported commands of a namespace using '''namespace export''' in the
exporting namespace, I found no way to query all imported commands
inside the importing namespace.

The documentation of '''namespace import''' said nothing about the
behaviour, if no arguments were given, and testing '''namespace
import''' without arguments resulted in nothing, in a no-op.

Prompted by this, I started a thread in news:comp.lang.tcl which goes
into more detail
[http://groups.google.com/group/comp.lang.tcl/browse_frm/thread/9fb246cf65aba54f?tvc=1].

What seems to be more logical to me would be to change the no-op
behaviour of '''namespace import''' to be comparable to '''namespace
export''', and return all imported commands inside the namespace
'''namespace import''' is executed in.

As an example...

 * to get all exported commands of a namespace ::exportingNspc:

| namespace inscope ::exportingNspc {namespace export}

 * to get all imported commands of the namespace ::importingNspc:

| namespace inscope ::importingNspc {namespace import}

~ Consequences

The only consequence I know is, that old scripts using the no-op
'''namespace import''' suddenly will return a list, probably filled
with names of imported commands. That's all.

Because of the fact, that '''namespace import''' never returned
values, no script should really break, thus no script should require
values from this command.

~ Proposed Change

The result of '''namespace import''' without arguments shall be a list
of all commands that have been imported into the current namespace.
Each command in the list will be the simple name by which the command
is known in the current namespace.  This format for the
returned value is most useful because it composes well
with '''namespace forget'''.  To remove all imported
commands from a namespace, use the command

| namespace forget {*}[namespace import]

~ Implementation

A patch implementing an earlier draft is available,
[http://sf.net/tracker/?func=detail&aid=1437008&group_id=10894&atid=310894],
and updated patches will be attached to the same Tracker report.

~ Copyright

This document has been placed in the public domain.