fix issue #2552: if no motor controller name is given, build controller name with config md5 hash, to ensure good cache per controller

Sebastien Petitdemange authored Jun 26, 2020 and Matias Guijarro committed Oct 23, 2020

Can serve counters and temperature objects.

config: Node object refactoring to allow on-demand references evaluation, and improvements on cloning and conversion to dictionary

* introduction of the Reference object
    - reference object has an 'eval' function to evaluate a reference
    - evaluation returns an object from config, or the value of an object attribute
* '$' prefix in YAML values now creates a Reference
    - no reference evaluation at YAML parsing time
* backward compatibility
    - getting a key with a reference returns the value, not the Reference
        * => introduction of ConfigList object to represent lists
    - '.raw_*' methods returns the raw contents, ie. with Reference objects instead of reference evaluated values
* node filenames are kept in Node objects
    - removed 'node2file' dictionary
* nodes are indexed automatically when inserting a 'name' key
    - no need for 'create_index'
    - same for tags
* '.to_dict()' method relies on the Python JSON decoder
    - simplification of the code
* '.deep_copy()' is renamed to '.clone()'
* '.deep_copy()' now relies on pickle
    - simplification of the code
    - nodes need a reference to the Config object => a trick is used to allow pickling/unpickling
        * the config object is saved to a tmp dict on pickling, and popped out on unpickling
* removed call to 'gc.collect()'
    - unclear why it was there at the first place
* removed weakref to Config object in nodes
    - nodes need the config, the config has to stay alive as long as nodes are there

Piergiorgio Pancino authored May 27, 2020 and Benoit Formet committed May 27, 2020

- option to not raise exception ported from method to an instance attribute
  (allows starting and reloading the page without exceptions)
- Improved exception handling and messages for user

Piergiorgio Pancino authored May 25, 2020 and Benoit Formet committed May 27, 2020

                    situations, specifically when there is a duplicated key in the same
                    file or in another file.
web.configuration.config_app: reload configuration not raising exception in case of
                    some misconfigurations

 - comment saving is now possible
 - updated all bliss modules using pyyaml

As motors and temperature object are insert into the map only once,
no need to update.

config plugin can now yield intermediate object creation to avoid infinite
recursion.

- now deep_copy change the parent with the copied parent =>
  get_inherited on reference object works.

Sebastien Petitdemange authored Jun 28, 2019 and Antonia Beteva committed Jun 28, 2019

+ fixed save for copied node

* added 'add_axes_counter' keyword arg to 'config.get'
    - do not add to map if object is created from another object

* moved Reference class from emotion to utils
    - 'replace_reference_by_object' uses Reference objects by default
* allow empty names, both for motor controllers or temperature controllers
* controllers are not returned from config plugin, if no name has been given