import ply instead of including it in the distribution

[johnyf]

Since ply is developed separately, importing it from site-packages will benefit from any updates and upgrades it experiences.

[victorlei]

Please be more specific -- such and such improvements in ply are currently missing in smop and would help smop in such and such ways.

[johnyf]

There are not specific features which I have in mind, the reason was more because it is a package maintained separately and can be installed automatically as a dependency from pypi or whichever other method each user prefers. One observation is that the included yacc is at version 3.3, whereas the current ply is at version 3.5. The minimal benefit will be to automatically follow updates, when users update their installed packages. Otherwise any changes would have to be committed also here.

Since setup does require other packages (numpy, scipy) the smop package is not entirely independent. So numpy and scipy will be fetched in case they are not already installed, hence fetching ply will not be the only cause of installing dependencies during setup.

Another idea might be to use a git submodule (haven't tried it).