upvar bad level error

[jemptymethod]

Somebody suggested the following code to me for debugging an http
request:

package require http
set tok [http::geturl http://localhost:1565/pgn4desk.htm]
upvar $tok token
set token(body) ""
parray token

However it results in the following error. I still haven't wrapped my
head around upvar :( Hopefully in the near future as I use Tcl more
and more. Thanks in advance for any guidance:

$ ./tclkit-cli pgn4desk.vfs/debug.tcl
bad level "::http::1"
while executing
"upvar $tok token"
(file "pgn4desk.vfs/debug.tcl" line 3)

[Uwe Klein]

# there is no level further up than (the current) toplevel scope thus
# upvar wants that optional level argument:
upvar #0 $tok token

set token(body) ""
parray token

#or

package require http
set tok [http::geturl http://localhost:1565/pgn4desk.htm]

set ${tok}(body) ""
parray $tok

uwe

[Alexandre Ferrieux]

On Jul 23, 1:09 pm, Uwe Klein <uwe_klein_habertw...@t-online.de>
wrote:

> jemptymethod wrote:
> > Somebody suggested the following code to me for debugging an http
> > request:
>
> > package require http

> > set tok [http::geturlhttp://localhost:1565/pgn4desk.htm]

> > upvar $tok token
> > set token(body) ""
> > parray token
>
> > However it results in the following error.  I still haven't wrapped my
> > head around upvar :(  Hopefully in the near future as I use Tcl more
> > and more.  Thanks in advance for any guidance:
>
> > $ ./tclkit-cli pgn4desk.vfs/debug.tcl
> > bad level "::http::1"
> >     while executing
> > "upvar $tok token"
> >     (file "pgn4desk.vfs/debug.tcl" line 3)
>
> package require http

> set tok [http::geturlhttp://localhost:1565/pgn4desk.htm]

> # there is no level further up  than (the current) toplevel scope thus
> # upvar wants that optional level argument:
> upvar #0 $tok token
>
> set token(body) ""
> parray token
>
> #or
> package require http

> set tok [http::geturlhttp://localhost:1565/pgn4desk.htm]

> set ${tok}(body) ""
> parray $tok
>
> uwe

Note that the confusing error message

bad level "::http::1"

is now (8.6) replaced by the accurate

bad level "1"

since the root cause of the problem is the fact that, without an
explicit level, upvar assumes [upvar 1] (meaning one up), which here
is invalid as you said, since we're already at toplevel.

This message improvement was part of the fix for bug 2673163:

https://sourceforge.net/tracker/index.php?func=detail&aid=2673163&group_id=10894&atid=110894

-Alex