Feature: template in configuration file, 2nd variation

[kparasch]

An unfinished example of a Template category in accelerator that allows generation of devices from templates. Uses a "template resolver" to generate from templates.

Due to the way files are expanded. An "ugly" solution was used to make sure templates have been loaded before the rest of the file. It is unclear if a more elegant solution can be found.

The template class uses the standard python string ".format" function to replace text and generate the template. Internally, it serializes a config dictionary to a yaml string, makes the replacement, and then de-serializes the yaml string into a new config dictionary.

example config with template:

class: pyaml.accelerator.Accelerator
machine: sr
facility: PETRAIII
energy: 6e9
controls:
 - class: tango.pyaml.controlsystem.TangoControlSystem
   tango_host: ebs-simu-3:10000
   name: live
   catalog:
     class: tango.pyaml.tango_catalog.TangoCatalog
     disconnected: True
devices:
- ${template:SHI,SHI,01}
- ${template:SHI,SHI,02}
- ${template:SHI,SHI,03}
templates:
  - name: SHI
    parameters:
      - sh_name
      - ii
    config:
      class: pyaml.magnet.hcorrector.HCorrector
      name: "{sh_name}-{ii}"
      model:
        class: pyaml.magnet.linear_model.LinearMagnetModel
        unit: rad
        hardware_unit: str
        calibration_factor: 1.0
        powerconverter: tango/MAGNET/{sh_name}-{ii}/B1L