raise custom exceptions when pyclipper fails

[anthrotype]

When an invalid contour is received as a subject or clipping path, pyclipper raises its own ClipperException error.

I wouldn't want clients to have to import pyclipper in order to handle the exception. I believe that should stay private as we may decide to replace pyclipper with another implementation in the future.

So we need to define our own custom exceptions, and re-raise the pyclipper.ClipperException as booleanOperations.BooleanOperationsError.

For example, one could do:

import booleanOperations

try:
    # perform some booleanOpertions
except booleanOperations.BooleanOperationsError:
    # handle the exception

The custom errors are defined in the booleanOperations.exceptions module. For convenience, the generic one is also exported in the top-level module as booleanOperations.BooleanOperationsError.

Note that previously, we were calling pyclipper's AddPaths method, which only raised when all the input path are invalid; I replaced it with AddPath (in a loop), so we can raise when any input path is invalid, and report which one in the exception message, so the user can find it more easily.

[anthrotype]

@typemytype shall I tag and publish v0.6.0 with the new custom exceptions?

[typemytype]

Yes please Thanks

On Monday, 17 October 2016, Cosimo Lupo notifications@github.com wrote:

@typemytype https://github.com/typemytype shall I tag and publish v0.6.0 with the new custom exceptions?

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gr Frederik www.typemytype.com