Hi,

I would like to add "chan exists str" just to signal a boolean return on exists and I want to do this
*without* to touch the tcl distribution.

there is already a feature like "::tcl:mathfunc::????" to add an additional function to "expr" and I
ask me now it is possible to do such a kind of "addition" to the "chan" command as well ?

mfg ao

On 17/06/2024 15:20, aotto1968 wrote:
>  I would like to add "chan exists str" just to signal a boolean return
> on exists and I want to do this
>  *without* to touch the tcl distribution.
>
>  there is already a feature like "::tcl:mathfunc::????" to add an
> additional function to "expr" and I
>  ask me now it is possible to do such a kind of "addition" to the
> "chan" command as well ?
>
The chan command is an ensemble, so you can add your own subcommands. It
is a bit more work than adding a math function, but not too much:

proc chanexists {fd} {
return [expr {$fd in [chan names]}]
} namespace ensemble configure chan -map [dict replace \
[namespace ensemble configure chan -map] exists ::chanexists]

After that, you get the following results:
% chan help
unknown or ambiguous subcommand "help": must be blocked, close,
configure, copy, create, eof, event, exists, flush, gets, names,
pending, pipe, pop, postevent, push, puts, read, seek, tell, or truncate
% chan exists stdin
1 % chan exists nosuchchan
0

Schelte.

thanks … the technology to add my own ensemble-command into an existing ensemble should be more used.

On 17.06.24 16:11, Schelte wrote:
> On 17/06/2024 15:20, aotto1968 wrote:
>>   I would like to add "chan exists str" just to signal a boolean return on exists and I want to do this
>>   *without* to touch the tcl distribution.
>>
>>   there is already a feature like "::tcl:mathfunc::????" to add an additional function to "expr" and I
>>   ask me now it is possible to do such a kind of "addition" to the "chan" command as well ?
>>
> The chan command is an ensemble, so you can add your own subcommands. It is a bit more work than adding a math function, but not
> too much:
>
> proc chanexists {fd} {
>     return [expr {$fd in [chan names]}]
> }
> namespace ensemble configure chan -map [dict replace \
>   [namespace ensemble configure chan -map] exists ::chanexists]
>
> After that, you get the following results:
> % chan help
> unknown or ambiguous subcommand "help": must be blocked, close, configure, copy, create, eof, event, exists, flush, gets, names,
> pending, pipe, pop, postevent, push, puts, read, seek, tell, or truncate
> % chan exists stdin
> 1
> % chan exists nosuchchan
> 0
>
>
> Schelte.
>

On 17.06.24 16:11, Schelte wrote:
> chan exists stdin

question: is this possible with an additional level?

proc chanexists {fd} {
return [expr {$fd in [chan names]}]
} namespace ensemble configure chan -map [dict replace \
[namespace ensemble configure chan -map] exists ::chanexists]

#chan help

puts [chan exists stdin] ; # → OK

# problem: "ensemble" is an ensemble IN the "namespace" ensemble
# goal: namespace ensemble add ENSEMBLE NAME CMD

proc ::namespace_ensemble_add {ensb name cmd} {
namespace ensemble configure $ensb -map [dict replace \
[namespace ensemble configure $ensb -map] $name $cmd]
}

→ how I do this for a *two* level ensemble (ensemble in a ensemble) ?

ok… "namespace ensemble" is not an ensemble"
namespace ensemble configure namespace -map =
children = ::tcl::namespace::children
code = ::tcl::namespace::code
current = ::tcl::namespace::current
delete = ::tcl::namespace::delete
ensemble = ::tcl::namespace::ensemble
eval = ::tcl::namespace::eval
exists = ::tcl::namespace::exists
export = ::tcl::namespace::export
forget = ::tcl::namespace::forget
import = ::tcl::namespace::import
inscope = ::tcl::namespace::inscope
origin = ::tcl::namespace::origin
parent = ::tcl::namespace::parent
path = ::tcl::namespace::path
qualifiers = ::tcl::namespace::qualifiers
tail = ::tcl::namespace::tail
unknown = ::tcl::namespace::unknown
upvar = ::tcl::namespace::upvar
which = ::tcl::namespace::which
namespace ensemble configure ::tcl::namespace::ensemble -map = "::tcl::namespace::ensemble" is not an ensemble command
info body ::tcl::namespace::ensemble = "::tcl::namespace::ensemble" isn't a procedure