UNC problem on Windows & conda when launching DOT to render plots about schedula HOT 8 CLOSED

UNC paths are supported on windows. To solve your issue you can set the module variable as follows:

import schedula.utils.drw as mdl
setattr(mdl, '_UNC', '')

from schedula.

What if longer than 260 chars is needed?

from schedula.

You have to solve the problem with the CMD.EXE.

from schedula.

So i guess the answer to my "what if" question is that "without UNC paths, schedula will fail for longer than 260-char paths", correct?
And that is why you suggest to fix the CMD problem. correct?

Now, that CMD.exe, i wouldn't be so assertive it is my problem...

from schedula.

Please re-open.

The issue is caused by a difference in the way Graphviz suite installs on Windows,

• when downloading and installing it from the site, or
• when using conda install graphviz.

TL;DR, in conda, the default executable extension is BAT, not exe, and BAT cannot handle UNC paths as CWD.

Normally there wouldn't be an issue, if schedula were not using UNC-paths.
(problem reported also in respective feedstock conda-forge/graphviz-feedstock#34)

Workaround

The dot.exe in conda's Graphvis in inside graphviz/ dir from where the bat is installed:

def is_conda():
    return os.path.exists(os.path.join(sys.prefix, 'conda-meta'))

if os.name == 'nt' and not os.path.splitext(prg)[1] and is_conda():
    monkeypatch_graphviz()

The monkeypatch_graphviz() must change the lines graphviz/backend.py#L124-L125 from this:

    if PLATFORM == 'windows':
        engine = '%s.bat' % engine

to this:

    if PLATFORM == 'windows':
        engine = 'graphviz\%s.exe' % engine

NOTE: you wont find the "from" lines in the original sources of the graphviz project, or in a non-conda Python - these lines are delivered by a conda-patch.

from schedula.

I'm sorry but your patch is invalid. You have used the wrong graphviz library (conda install -c conda-forge graphviz).

The graphviz requirement in schedula corresponds to conda install -c conda-forge python-graphviz=0.8.4.

from schedula.

You seem to be confusing:

• python-graphviz (python) and
• graphviz the native OS suite.

The former, depends on the later, you can't have one or the other, you need both in conda.

My patch is a temporary fix for schedula's UNC paths to play well there, n particular, with python-graphviz, until they fix this upstream (conda-forge/graphviz-feedstock#34, comment).

from schedula.

But the old version python-graphviz-8.4 indeed solves the problem 👍
(reported in graphviz-feedstock-34).

I'm not asking to add this version-boundary to scheulas setup.py since is only involves conda environments - not PyPi packages.

from schedula.