[IPython-dev] What To Do With a Problem Like 'cd /'?
danmil at comcast.net
Wed May 23 11:38:23 EDT 2007
As Ville noted below, subsequent to the prefilter reorg, 'cd /' now
gives a syntax error, whereas before, it successfully expanded to an
I've tracked the issue down, but I'm not sure what the proper
behavior should be.
The problem is that the system is now being far more careful about
paying attention to possible python operators on a line. This
started with a commit by Fernando a month+ ago:
This tries to avoid certain bad autocall issues by checking for the
following chars as the start of the rest of a line, and it finds one,
just handling the line normally:
Note how '/' is now in there. When I reorg'd things, I put that
check in prefilter.checkPythonChars, which gets called *before*
checkAutomagic. Thus, when you type:
: cd /
The system sees the /, and says, basically, "Oh, this looks like it
might be a valid python expression, so I'm going to just handle it
normally (and thus not expand the magic cd)".
I'm not sure if this should or should not be 'fixed'. I mean, OTOH,
'cd /' is pretty damn useful. On the other hand, there are some
weird interactions among the various namespaces, and being
consistently careful and respectful of possible python operators
seems like a good, safe practice.
You can work around it with "cd '/'" or "cd \/" (though, ugh).
Or I can maybe special case assignment separately from all the other
python chars, and only check for that before expanding automagics (so
that the full pythonChar check just comes before autocall
expansion). I *think* that would be safe, but I would not swear to it.
What do people think?
On May 21, 2007, at 4:00 AM, Ville M. Vainio wrote:
> On 5/16/07, Dan Milstein <danmil at comcast.net> wrote:
>> ...finally ;-)
>> Okay, I just went ahead and committed it to the trunk (r. 2354).
> Possible regression: "cd /" now gives syntaxerror, instead of being
> caught as a proper magic command. cd \ and other cd invocations work
> Ville M. Vainio - vivainio.googlepages.com
> blog=360.yahoo.com/villevainio - g[mail | talk]='vivainio'
More information about the IPython-dev