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From: Randy Melton on 24 Feb 2010 20:11
consider the following:

namespace eval a {}
proc a::unknown {args} {puts stderr "my unknown ..."}
namespace eval a {namespace unknown ::a::unknown}
a::help
--> invalid command name "a::help"
namespace eval a {help}
--> my unknown ...

I assumed that the unknown handler local to the namespace would be
invoked? I can see why you might want the global unknown, but it
wasn't obvious what would happen.
From: slebetman on 25 Feb 2010 04:57
On Feb 25, 9:11 am, Randy Melton <seade...(a)gmail.com> wrote:
> consider the following:
>
> namespace eval a {}
> proc a::unknown {args} {puts stderr "my unknown ..."}
> namespace eval a {namespace unknown ::a::unknown}
> a::help
> --> invalid command name "a::help"
> namespace eval a {help}
> --> my unknown ...
>
> I assumed that the unknown handler local to the namespace would be
> invoked?  I can see why you might want the global unknown, but it
> wasn't obvious what would happen.

namespace unknown catches unknown procs that are executed in the given
namespace. You are instead attempting to execute a proc defined in a
given namespace in the current (global) namespace which is why the
unknown mechanism for the current namespace is invoked. If instead you
did:

namespace eval a {help}

then you would have triggered the unknown mechanism for namespace "a".
From: Randy Melton on 25 Feb 2010 13:42
On Feb 25, 2:57 am, "slebet...(a)yahoo.com" <slebet...(a)gmail.com> wrote:
> namespace unknown catches unknown procs that are executed in the given
> namespace. You are instead attempting to execute a proc defined in a
> given namespace in the current (global) namespace which is why the
> unknown mechanism for the current namespace is invoked. If instead you

I'm not sure this is true. I think a::help is "launched" from the
global namespace but executes in the "a" namespace. I believe the
distinction between launch/execution namespace is is unclear in the
"namespace unknown" command. I believe I clearly understand what is
happening, I'm just questioning the implementation. One of the things
I appreciate in Tcl is that most things follow pretty clear rules. I
think this launch vs execution namespace WRT unknown is at best
ambiguous. One might expect a::help to behave the same as namespace
eval a {help}.

I've read the TIP (http://www.tcl.tk/cgi-bin/tct/tip/181.html) several
times trying to understand the implementation constraints. When the
phrase "current namespace" is used I think it refers to the launch
namespace then later it seems to refer to execution namespace. (step 4
in the "to this" section.)

For the issue at hand I found "let unknown know" and the "namespace
unknown" version (http://wiki.tcl.tk/12790) very useful. Using those
I added a handler to watch for a::* and dispatch those calls to
a::unknown.

thanks,
randy
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