Re: Question about connecting to a node and proposed patch

Matthias,

Matthias Radestock <[email protected]> writes:

> Bill Clementson <[email protected]> writes:
>
>> Have you tried debugging the erl-check-backend call to determine why
>> it's failing to load the distel beam files on the target node or do
>> you have any clues as to why it's not working (other than the badrpc
>> messages)?
>
> I have only spent a short time debugging this problem. I have a
> workaround (using .erlang) that works ok, and my elisp debugging skills
> aren't strong enough to be confident I would be able to fix the issue in a
> reasonable time. I'll give it another try though when I have a spare few
> hours.
>
>>> I use "C-c C-d n" for its documented purpose - to select "the nodename
>>> to connect to in future.". So, for example, I often use the same node
>>> for a long time and frequently restart it, and don't want to have to
>>> think about / find out whether the node is up or down when typing "C-c
>>> C-d n".
>>
>> But, since all "C-c C-d n" seems to do is change the current node that
>> distel deals with and update the node name in the mode line [...]
>
> Correct. And that is all it is supposed to do. I want to keep it that
> way.
>
>> However, I agree that my patch doesn't deal with nodes that are
>> bumped/restarted.
>
> That is a major regression. Not from the current state of affairs,
> obviously, but from the original design and how things work when not
> using the new auto code-loading feature.
>
>>> As a stop-gap solution, may I suggest another key-bound command
>>> "erl-ping" which executes the erl-spawn call from your patch on
>>> (erl-target-node), i.e. it will work like most other distel commands by
>>> prompting for a node if none is currently selected and performing the
>>> action (in this case a call to erlang:node()) on it. 
>>
>> I dislike having a separate "erl-ping" function as it is something
>> that one has to manually do (and know when to do it).
>
> You can invoke that command *instead* of "C-c C-d n" in order to connect
> (rather than just select) the first time, and subsequently reconnect
> after node bounces. This isn't any more manual than what you currently
> do; it's just a different command.

ok

> To let us switch nodes, we make the command prompt us for a node name
> when invoked with a prefix argument (C-u ...) - something I wish all
> distel commands did. Give this code a try:
>
> (defun erl-ping (node)
>   "Ping the NODE, uploading distel code as a side effect."
>   (interactive (list (if current-prefix-arg
>                          (erl-choose-nodename)
>                        (erl-target-node))))
>   (erl-spawn
>     (erl-send-rpc node 'erlang 'node nil)
>     (erl-receive (node)
> 	((['rex response]
>           (if (equal node response)
>               (message "Successfully communicated with remote node %S"
>                        node)
>             (message "Failed to communicate with node %S: %S"
>                      node response)))))))
>
> So, to connect and reconnect just run 'M-x erl-ping'. To switch nodes
> (and connect) run 'C-u M-x erl-ping'.

Works for me. 

> Any suggestions for a key-binding? 'C-c C-d @' or 'C-c C-d !' perhaps?

"C-c C-d @" seems appropriate.

- Bill


-------------------------------------------------------------------------
This SF.net email is sponsored by DB2 Express
Download DB2 Express C - the FREE version of DB2 express and take
control of your XML. No limits. Just data. Click to get it now.
http://sourceforge.net/powerbar/db2/