YAML isn't part of the Python standard library, while JSON is.
If we want `setup.py` to dynamically parse the available integration
manifest files in order to populate the extra dependencies, then it's
better to rely on a JSON format for manifest files - the parser is part
of the standard library and it doesn't require the user to install
`pyyaml` before `platypush`.
continuous-integration/drone/push Build is passingDetails
The `variable` plugin may break in the constructor the first time the
application is started.
That's because it tries to initialize the cache of stored variables, but
the local database hasn't yet been initialized.
That's because plugins are registered _before_ the entities engine is
initialized, as the entities engine assumes that it already has plugins
to scan for entities.
Therefore, the initialization of the `variable` plugin's cache should be
lazy (only done upon the first call to `get`/`set` etc.), in order to
prevent deadlock situations where the plugin waits for the engine to
start, but the engine will be initialized only after the plugin is
ready.
And the lazy initialization logic should also ensure that the entities
engine has been properly started (and emit a `TimeoutError` if that's
not the case), in order to prevent race conditions.
`delete` will actually remove the record from the database (same as
`unset`'s new behaviour), while `unset` will set it to null without
deleting it (same as the `unset`'s previous behaviour).
`entities.transform_entities` will pass back an empty list instead of an
empty dict if no entities were found, and the function should be able to
handle it.
Fabio Manganiello