Raise exceptions on ill-formatted actions

[jonrkarr]

Here's an example of an ill-formatted action (missing end }) that pyBioNetGen doesn't raise an exception for and doesn't parse as intended

simulate_ssa({t_start=>0,t_end=>1000000,n_steps=>1000,seed=>2);

The parsed args for the action can be accessed as below

model.actions.items[0].args

This returns this data structure

[
    ('{t_start=>0', None), 
    ('t_end=>1000000', None), 
    ('n_steps=>1000', None), 
    ('seed=>2', None)
]

The first argument is not parsed as intended.

[ASinanSaglam]

We have a solution coming for this soon but it won't have custom exceptions unfortunately. Once we have a better parsing solution we'll have custom errors that will let the user know. I'll update the issue with the fix once the fix is pushed but I'll keep the issue open until the better parsing solution is implemented.

[jonrkarr]

I was imagining basic validation that just recognizes the general syntax for actions (comma-separated list enclosed in curly brackets).

Validation of the specific attributes associated with particular actions would be even better, but I wasn't trying to suggest that. Basic validation as outlined above would be helpful.

[ASinanSaglam]

This is partially addressed with 0.4.6 release. The actions now know their possible arguments and will raise an error if the argument is incorrect. Eventually with the full parser I'm hoping to point out the exact reason why something fails but until then this should catch majority of these hopefully.