zyga / arrowhead Goto Github PK

Currently when '-t x11' is used to display the dot rendering of the flow a confusing exception is raised:

zyga@iffy:~/arrowhead/examples$ ./tutorial1.py --preview -t x11
Traceback (most recent call last):
File "./tutorial1.py", line 61, in
main(HelloWorld)
File "/home/zyga/arrowhead/arrowhead/main.py", line 57, in main
viewer.update(flow_cls)
File "/home/zyga/arrowhead/arrowhead/main.py", line 144, in update
self.proc = subprocess.Popen(['dot', '-Txlib', self.dot_file.name])
File "/usr/lib/python3.2/subprocess.py", line 745, in init
restore_signals, start_new_session)
File "/usr/lib/python3.2/subprocess.py", line 1361, in _execute_child
raise child_exception_type(errno_num, err_msg)
OSError: [Errno 2] No such file or directory: 'dot'

Arrowhead should handle this situation with something better.

Arrowhead should have tests sufficient for making modifications to the core without the fear of introducing regressions.

Arrowhead should be packaged for Debian. Ideally this should happen after the 1.0 release with python2.7 support (optional) and tests (mandatory)

A lot of good people are still stuck on python2.7 for variety of reasons. Arrowhead should support them, if that does not collide with the goal of having excellent features (some of which may require python3.2)

The step level assignment algorithm is broken. It should maintain a set of nodes with known levels (starting with any pre-existing level as well as the initial state). Items from that set should be the TODO list of the level assignment loop. The algorithm should then reset all levels from all nodes so that it doesn't stop mid way on any pre-set level.

It is quite easy to inherit or create a flow from scratch in which some states are unreachable from the initial state. Such flows should be detected and reported

Many steps can be performed in parallel. Arrowhead should support this feature and allow the user to decide how the parallelism is implemented. The syntax is yet undefined but a simple example can be seen below:

@step(fork=True)
@arrow(to="task_a")
@arrow(to="task_b")
@arrow(to="task_c")
@arrow(to="oops", error=Exception)  # implicit fork=False)
def fork(step):
      """ fork all tasks """

@step
@arrow(to="join")
def task_a(step):
     """do stuff for task A"""


@step
@arrow(to="join")
def task_b(step):
     """do stuff for task B"""


@step
@arrow(to="join")
def task_c(step):
     """do stuff for task C"""


@step(join=True, accepting=True)
def join(step):
    """ join all tasks """

@step(accepting=True)
def oops(step):
    """ something went south """