is_string_like existed both in matplotlib and matplotlib.cbook

[NelleV]

This closes #1019.

is_string_like existed both in matplotlib and in matplotlib.cbook. The proposed fix was to remove is_string_like from cbook and import the one from matplotlib in cbook. I'm somewhat unsatisfied with this solution, but backward compatibility is completely maintained, and it is better than what existed before (code duplication).

[pelson]

is using basestring as the baseclass not preferred?

[mdboom]

Careful: basestring is not available on Python 3.x, and 2to3 converts it to merely str. This is decidedly not the behavior we want. Best to revert this to isinstance(x, (bytes, unicode)) and add a comment about why we aren't using basestring.

[NelleV]

I've got problems with the code right now. The proposed fix might not work because of circular imports.

I'll revert back to str and unicode, and add the comment.

[NelleV]

So, indeed I have a circular import in my current fix (cbook <- matplotlib <- rcsetup <- colors <- cbook).

I think it is problematic that the "utils" module (cbook) relies on importing matplotlib: this means it cannot be imported everywhere (in particular, in matplotlib.__init__). I think the safest way to proceed would be to split cbook into two: a part that depends on matplotlib for the rcparams dependency, and the rest in another file (including, all the validation methods which are needed in most of the modules). Another way to fix the problem would be to have the module rcsetup not relying on another module (here, colors), hence having matplotlib importable from any submodule of matplotlib.

Thoughts? Maybe this discussion should move on the mailing list, where more people could give their insights on the problem ?

[efiring]

I think #1762 solves the problem, so I am closing this.