BaseException.message has been deprecated as of Python 2.6

[Jun Omae]

If non-TRAC_ADMIN user requests with hdfdump=1 parameter and Python 2.6 is used, Python says DeprecationWarning.

python trac/web/standalone.py  -p 3000 -a '*,/home/jun66j5/src/trac-htdigest.txt,auth'  /dev/shm/testenv
Server starting in PID 19162.
Serving on 0.0.0.0:3000 view at http://127.0.0.1:3000/
Using HTTP/1.1 protocol version
/home/jun66j5/src/tracdev/git/trac/web/api.py:137: DeprecationWarning: BaseException.message has been deprecated as of Python 2.6
  self.detail = detail.message
192.168.11.11 - - [19/Dec/2014 13:03:40] "GET /testenv?hdfdump=1 HTTP/1.1" 403 -
192.168.11.11 - - [19/Dec/2014 13:03:40] "GET /testenv/chrome/site/your_project_logo.png HTTP/1.1" 404 -
192.168.11.11 - - [19/Dec/2014 13:03:40] "GET /testenv/chrome/site/your_project_logo.png HTTP/1.1" 404 -

[Ryan J Ollos]

Some of the comments in #11286 might be applicable.

[Ryan J Ollos]

While working on #11286 I remember seeing the following behavior: DeprecationWarning with Python 2.6, but not with Python 2.7.

(py2.6)user@ubuntu:~/Workspace/t11944$ python
Python 2.6.9 (default, Jan 25 2014, 21:02:08) 
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> e = Exception("the message")
>>> e.message
__main__:1: DeprecationWarning: BaseException.message has been deprecated as of Python 2.6
'the message'
>>> dir(e)
['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__getitem__', '__getslice__', '__hash__', '__init__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__setstate__', '__sizeof__', '__str__', '__subclasshook__', '__unicode__', 'args', 'message']

Python 2.7.6 (default, Mar 22 2014, 22:59:56) 
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> e = Exception("the exception")
>>> e.message
'the exception'
>>> dir(e)
['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__getitem__', '__getslice__', '__hash__', '__init__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__setstate__', '__sizeof__', '__str__', '__subclasshook__', '__unicode__', 'args', 'message']

I thought I had found an explanation for that somewhere on Stack Overflow, but I'm unable to find it now. Anyway, ​PEP:0352 claims the message attribute was removed in Python 3.0, and I can confirm it is gone at least in 3.4.

Python 3.4.0 (default, Apr 11 2014, 13:05:11) 
[GCC 4.8.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> e = Exception("the exception")
>>> dir(e)
['__cause__', '__class__', '__context__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__le__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__setstate__', '__sizeof__', '__str__', '__subclasshook__', '__suppress_context__', '__traceback__', 'args', 'with_traceback']

So it seems good to remove the message property from the TracError class for consistency. I did some work on that last weekend while I was offline that I'll post here soon for review.

[Ryan J Ollos]

Replying to rjollos:

So it seems good to remove the message property from the TracError class for consistency. I did some work on that last weekend while I was offline that I'll post here soon for review.

Proposed changes in log:rjollos.git:t11886.

[Ryan J Ollos]

Replying to jomae:

If non-TRAC_ADMIN user requests with hdfdump=1 parameter and Python 2.6 is used, Python says DeprecationWarning.

It looks like that's probably a PermissionError. Another way to avoid the deprecation warning would be to define the message property like the TracError class: tags/trac-1.0.2/trac/core.py@:48-49#L30​.

The Error class in ConfigParser.py has the following code:

# exception classes
class Error(Exception):
    """Base class for ConfigParser exceptions."""

    def _get_message(self):
        """Getter for 'message'; needed only to override deprecation in
        BaseException."""
        return self.__message

    def _set_message(self, value):
        """Setter for 'message'; needed only to override deprecation in
        BaseException."""
        self.__message = value

    # BaseException.message has been deprecated since Python 2.6.  To prevent
    # DeprecationWarning from popping up over this pre-existing attribute, use
    # a new property that takes lookup precedence.
    message = property(_get_message, _set_message)

In light of those hints, I may rework the proposed changes.

[Ryan J Ollos]

It seems to come down to:

1. Deprecate message property of TracError and HTTPException and remove uses of message in the codebase.

or

2. Add message property to the PermissionError class.

I'm slightly in favor of (1), for consistency with the BaseException class in Python 3. Any suggestions?

[Jun Omae]

I'm slightly in favor of (1), for consistency with the BaseException class in Python 3. Any suggestions?

+1 for (2).

We could remove uses of message in Trac core. I think we should do. However, we cannot remove uses in all plugins. Therefore, I think we should add message property to prevent the warnings.

[Ryan J Ollos]

Replying to jomae:

We could remove uses of message in Trac core.

Done in [13749:13750].

I think we should do. However, we cannot remove uses in all plugins. Therefore, I think we should add message property to prevent the warnings.

Additional proposed changes in log:rjollos.git:t11886.2 and log:rjollos.git:t11886.2-trunk.

[Ryan J Ollos]

OT: the variable name hdfdump might not make much sense now that ClearSilver is removed. Maybe we should add an alias, such as datadump? This came to mind while reading TracTroubleshooting#ClearsilversHDF.

[Jun Omae]

Additional proposed changes in log:rjollos.git:t11886.2 and log:rjollos.git:t11886.2-trunk.

Looks good to me.

[Jun Omae]

OT: the variable name hdfdump might not make much sense now that ClearSilver is removed. Maybe we should add an alias, such as datadump? This came to mind while reading TracTroubleshooting#ClearsilversHDF.

IMO, I'd like to leave with no changes. I don't think it would be good to add a magic token even if it makes much sense. If an alias is added, I like such as __datadump which it rarely conflicts with tokens from Trac core and other plugins.

[Ryan J Ollos]

Committed to 1.0-stable in [13769,13771], merged to trunk in [13770,13772,13774]. Additional change on trunk in [13773].