Improved dashing for black and white plots?

Hi all,

this is somewhat of a half-feature request, half-question. I just
went through a rather unpleasant exercise in trying to get a line plot
with about 8 traces generated for black and white printing. As it
turns out, mpl seems to only have 4 line styles ('-', '--', '-.',
':'), which isn't really a whole lot (compare this to gnuplot's
extensive dashing support). One can combine dashing with markers, but
the results aren't really very pretty (the relationship in spacing
between the dashing and the markers causes this, since the markers are
right at the data points while the dashing is whatever it is).

Mpl's color support is outstanding, but I need these figures in b/w
for a paper that will have no color figures, and I'm wondering what
others have resorted to in similar situations.

Additionally, I'd like to suggest having a b/w mode, where mpl's
auto-selection of different colors for successive line plots becomes a
rotation of dashing modes. Gnuplot's EPS backend has exactly this
feature, and it's absolutely fantastic: if color is on, it
auto-selects amongst many colors, but if color is off, it
automatically switches to contrasting dashing modes. This more or
less ensures that you can get the same plot made, either in color or
b/w, with nearly zero effort and still have distinguishable traces.
It's really nice to be able to generate a color version of the figures
for a talk and a b/w one for a paper, without hours of manual tweaks.

Anyway, I hacked an ugly-but-functional solution on my own, so this
message is mostly to put the issue on the radar, though I /am/
interested in solutions others may have.