[Twisted-Python] adding endpoint plugins

[exarkun at twistedmatrix.com]

On 03:50 pm, dstainton415 at gmail.com wrote:
>Hi Jean-Paul,
>
>Thanks for the suggestions.
>OK... here's my SSCCE:

It looks like you need to make an instance of 
`TorClientEndpointStringParser`.  If a class `implements´ an interface 
then instances of that class `provide´ the interface.

The plugin system searches for objects that `project´ the requested 
interface.

Jean-Paul
>cd projects/virtualenv-1.11.1/
>./virtualenv.py ~/virtenv-endpoints-test
>. ~/virtenv-endpoints-test/bin/activate
>usewithtor pip install twisted
>cd ~/projects
>git clone https://github.com/david415/txsocksx.git
>cd txsocksx
>git checkout endpoint_parsers
>usewithtor python setup.py install
>cd examples # CWD is now /home/human/projects/txsocksx/examples
>cp tor_client_endpoint_parser.py
>/home/human/virtenv-endpoints-test/lib/python2.7/site- 
>packages/twisted/plugins
>find /home/human/virtenv-endpoints-test/ -name "*.pyc" | xargs rm
>find /home/human/virtenv-endpoints-test/ -name "dropin.cache" | xargs 
>rm
>python tor-http.py
>Traceback (most recent call last):
>  File "tor-http.py", line 32, in <module>
>    torEndpoint = clientFromString(reactor,
>"tor:host=timaq4ygg2iegci7.onion:port=80")
>  File "/home/human/virtenv-endpoints-test/local/lib/python2.7/site- 
>packages/twisted/internet/endpoints.py",
>line 1737, in clientFromString
>    raise ValueError("Unknown endpoint type: %r" % (aname,))
>ValueError: Unknown endpoint type: 'tor'
>
>
>I also tried the PYTHONPATH trick:
>
>mkdir -p fu/twisted/plugins
>cp tor_client_endpoint_parser.py fu/twisted/plugins
>PYTHONPATH=/home/projects/txsocks/examples/fu python tor-http.py
>Traceback (most recent call last):
>  File "tor-http.py", line 32, in <module>
>    torEndpoint = clientFromString(reactor,
>"tor:host=timaq4ygg2iegci7.onion:port=80")
>  File "/home/human/virtenv-endpoints-test/local/lib/python2.7/site- 
>packages/twisted/internet/endpoints.py",
>line 1737, in clientFromString
>    raise ValueError("Unknown endpoint type: %r" % (aname,))
>ValueError: Unknown endpoint type: 'tor'
>
>
>I wonder if I am having a deployment problem here or if my code has
>got problems.
>https://github.com/david415/txsocksx/blob/endpoint_parsers/examples/tor_client_endpoint_parser.py
>https://github.com/david415/txsocksx/blob/endpoint_parsers/examples 
>/tor-http.py
>
>
>Cheers!
>
>David
>
>On Wed, Apr 30, 2014 at 2:14 PM,  <exarkun at twistedmatrix.com> wrote:
>>On 01:42 pm, dstainton415 at gmail.com wrote:
>>>
>>>Greetings,
>>>
>>>
>>>http://twistedsphinx.funsize.net/projects/core/howto/plugin.html
>>
>>
>>Note that's a random version of the documentation from who knows how 
>>long
>>ago.  If you want a random version of the documentation then I suggest 
>>using
>>http://twisted.readthedocs.org/en/latest/ instead.
>>>
>>>suggests that I can also set the PYTHONPATH to a directory:
>>
>>
>>Sure.  As a development environment trick.  Putting the module 
>>defining your
>>plugin into *the* twisted/plugins/ directory will reduce your runtime 
>>cost.
>>This is purely a deployment decision, though, so if you'd rather 
>>expand
>>PYTHONPATH then you can.
>>>
>>>"""if a directory which has been added to sys.path (typically by
>>>adding it to the PYTHONPATH environment variable) contains a 
>>>directory
>>>named twisted/plugins/ , each .py file in that directory will be
>>>loaded as a source of plugins."""
>>>
>>>I'm using twisted 13.2.0 in a virtualenv... and I've tried setting
>>>PYTHONPATH to a "twisted/plugins" directory no avail. I must be doing
>>>something wrong here but after scouring the docs and twisted source
>>>code... I'm just not sure.
>>
>>
>>I don't think there's enough information here to debug your problem. 
>>Try
>>coming up with an http://sscce.org/ or at least providing all of the 
>>details
>>about your setup - the exact value of PYTHONPATH, the command you use 
>>to
>>launch the program, the working directory you use, the complete, exact
>>filesystem hierarchy starting at the top-most directory containing any 
>>code
>>you wrote or expect to be in use, etc.
>>
>>Some random suggestions that have helped other people and might help 
>>you but
>>who knows:
>>
>>  * delete all the dropin.cache files you can find and try again
>>  * delete all the .pyc files you can find and try again
>>  * put absolute paths into PYTHONPATH, not relative paths
>>  * don't put "/foo/bar/twisted/plugins" into PYTHONPATH, put 
>>"/foo/bar"
>>  * Make sure your plugin *provides* the plugin interface and IPlugin. 
>>This
>>is not the same *implementing* those interfaces.
>>
>>Good luck,
>>Jean-Paul
>>
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