Remove added binding command

[Harald Oehlmann]

Hi TCL'ers,

is there a common method to remove added binding commands:

Existing binding command:
bind . a otherhandler

My own binding;
bind . a +myhandler

Another module adds its handler:
bind .a +anotherhandler

Is there a common way to remove myhandler from the list of bindings
without touching the other ones ?

Thank you,
Harald

[Harald Oehlmann]

I wrote this procedure to do the job:

# Remove first Cmd from bind pattern.
# @return true if removed
proc gui::guiBindRemove {Win Pattern CmdIn} {
set CmdCur [bind $Win $Pattern]
while {-1 != [set Pos [string first $CmdIn $CmdCur]]} {
# >> Check if found string starts at the beginning of after a
new-line
if { $Pos == 0 || [string index $CmdCur $Pos-1] eq "\n" } {
# >> Check if found string ends at end or before a new-line
set PosEnd [expr {$Pos + [string length $CmdIn]}]
if { $PosEnd == [string length $CmdCur]
|| [string index $CmdCur $PosEnd] eq "\n"
} {
# Binding found
if {$Pos != 0} {
set CmdNew [string range $CmdCur 0 $Pos-2]
} else {
set CmdNew ""
}
if {$PosEnd!= [string length $CmdCur]} {
if {$CmdNew ne ""} {
append CmdNew \n
}
append CmdNew [string range $CmdCur $PosEnd+1 end]
}
bind $Win $Pattern $CmdNew
return 1
}
}
}
return 0
}

Is this wise ?
Should it go to the wiki ?
Or in a TIP for bind Win Pattern -CmdIn ?

Thanks,
Harald

[Christian Gollwitzer]

Am 12.04.19 um 15:38 schrieb Harald Oehlmann:

Yes, don't add it in this way, it is a misdesign of Tk events. There is
another level of indirection, the bindtags. Bindtags are a list, and
therefore you can easily add and remove bindings. Snit, e.g., manages
this for you, if you use a snit::widgetadaptor.

Another way, if you "misuse" virtual events for signalling between
modules in a big program, I suggest you take a look at uevent. This is a
module in tcllib which implements an event mechanism disconnected from
Tk, and there each handler/listener gets a token (similar to an afterid)
with which you can unsubscribe. This is way cleaner of you have non-GUI
objects.

Christian

[Harald Oehlmann]

Thank you, Christian, so I am not missing the obvious.

I am in AndroWish where a lot of information valid for a lot of modules
is delivered by virtual events.

bind . <<WillEnterBackground>> +ScannerUnregister

I wanted to add a command without disturbing any other modules using the
same virtual event.

I suppose, I can not use nor bindtags, nor uevent for this purpose.

By the way, in my posted program, there is an infinite loop.

Thanks,
Harald

[Harald Oehlmann]

I have add all this on a wiki page:

https://wiki.tcl-lang.org/page/bind%3A+remove+one+command

Enjoy,
Harald

[Christian Gollwitzer]

Am 12.04.19 um 17:28 schrieb Harald Oehlmann:

> I am in AndroWish where a lot of information valid for a lot of modules
> is delivered by virtual events.
>
> bind . <<WillEnterBackground>> +ScannerUnregister

This is the classic case of "misusing" Tk events - an event which has
multiple listeners cannot be cleanly expressed in Tk.

>
> I wanted to add a command without disturbing any other modules using the
> same virtual event.
>
> I suppose, I can not use nor bindtags, nor uevent for this purpose.

Yes, you can - if you have all the modules under your control. Refire
the event as a uevent in the main setup:

bind . <<WillEnterBackground>> { uevent::generate AndroidWish GoesDown }

then, in each module, you do:

set myid [uevent::bind AndroidWish GoesDown mymethod]

and when you unload the module

uevent::unbind $myid


We use uevent in aRTist precisely to do this - signalling general events
that are not connected to a widget.

Christian

[Mike Griffiths]

You can still use bindtags:

> bindtags
. Wish all
> bindtags . [linsert [bindtags .] 1 CustomFoo]
> bindtags .
. CustomFoo Wish all
> bind CustomFoo <<WillEnterBackground>> [list ScannerUnregister]

(Output above is on Wish on Windows; default bindtags may be different on AndroWish, or already altered by other libraries, but by using [linsert] as above you can inject your new bindtag safely regardless)

[Gerald Lester]

On 4/12/19 12:49 PM, Christian Gollwitzer wrote:
> Am 12.04.19 um 17:28 schrieb Harald Oehlmann:
>> I am in AndroWish where a lot of information valid for a lot of modules
>> is delivered by virtual events.
>>
>> bind . <<WillEnterBackground>> +ScannerUnregister
>
> This is the classic case of "misusing" Tk events - an event which has
> multiple listeners cannot be cleanly expressed in Tk.

This is not so much a misuse as a very old way of doing things that
predates bindtags.

IMHO, this should not appear in any modern code, instead make use of
bindtags.

>>...

--
+----------------------------------------------------------------------+
| Gerald W. Lester, President, KNG Consulting LLC |
| Email: Gerald...@kng-consulting.net |
+----------------------------------------------------------------------+

[sled...@gmail.com]

slightly off topic...uevent is a super solution.

However, Komodo IDE crashes upon "package require uevent". Otherwise, I like the IDE

Is there another IDE\debugger that you would recommend? Have tried Ramdebugger, but like Komodo (for tcl) , not really supported

Rick