frappy/secop/metaclass.py
Markus Zolliker 5c33cbf7a5 introduce update callbacks
includes a use case:
- a software calibration, to be applied to any Readable.
- calibration could be changed on the fly

+ refactored a little bit update events mechanism

Change-Id: Ifa340770caa9eb2185fe7e912c51bd9ddb411ece
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/23093
Tested-by: JenkinsCodeReview <bjoern_pedersen@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>
2020-05-15 15:49:22 +02:00

229 lines
10 KiB
Python

# -*- coding: utf-8 -*-
# *****************************************************************************
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation; either version 2 of the License, or (at your option) any later
# version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc.,
# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
# Module authors:
# Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
# Markus Zolliker <markus.zolliker@psi.ch>
#
# *****************************************************************************
"""Define Metaclass for Modules/Features"""
from collections import OrderedDict
from secop.errors import ProgrammingError, BadValueError
from secop.params import Command, Override, Parameter
from secop.datatypes import EnumType
from secop.properties import PropertyMeta
class Done:
"""a special return value for a read/write function
indicating that the setter is triggered already"""
# warning: MAGIC!
class ModuleMeta(PropertyMeta):
"""Metaclass
joining the class's properties, parameters and commands dicts with
those of base classes.
also creates getters/setter for parameter access
and wraps read_*/write_* methods
(so the dispatcher will get notfied of changed values)
"""
def __new__(cls, name, bases, attrs):
commands = attrs.pop('commands', {})
parameters = attrs.pop('parameters', {})
overrides = attrs.pop('overrides', {})
newtype = type.__new__(cls, name, bases, attrs)
if '__constructed__' in attrs:
return newtype
newtype = PropertyMeta.__join_properties__(newtype, name, bases, attrs)
# merge accessibles from all sub-classes, treat overrides
# for now, allow to use also the old syntax (parameters/commands dict)
accessibles_list = []
for base in reversed(bases):
if hasattr(base, "accessibles"):
accessibles_list.append(base.accessibles)
for accessibles in [parameters, commands, overrides]:
accessibles_list.append(accessibles)
accessibles = {} # unordered dict of accessibles, will be sorted later
for accessibles_dict in accessibles_list:
for key, obj in accessibles_dict.items():
if isinstance(obj, Override):
if key not in accessibles:
raise ProgrammingError("module %s: can not apply Override on %s: no such accessible!"
% (name, key))
obj = obj.apply(accessibles[key])
accessibles[key] = obj
else:
if key in accessibles:
# for now, accept redefinitions:
print("WARNING: module %s: %s should not be redefined"
% (name, key))
# raise ProgrammingError("module %s: %s must not be redefined"
# % (name, key))
if isinstance(obj, Parameter):
accessibles[key] = obj
elif isinstance(obj, Command):
# XXX: convert to param with datatype=CommandType???
accessibles[key] = obj
else:
raise ProgrammingError('%r: accessibles entry %r should be a '
'Parameter or Command object!' % (name, key))
# Correct naming of EnumTypes
for k, v in accessibles.items():
if isinstance(v, Parameter) and isinstance(v.datatype, EnumType):
v.datatype._enum.name = k
# newtype.accessibles will be used in 2 places only:
# 1) for inheritance (see above)
# 2) for the describing message
newtype.accessibles = OrderedDict(sorted(accessibles.items(), key=lambda item: item[1].ctr))
# check for attributes overriding parameter values
for pname, pobj in newtype.accessibles.items():
if pname in attrs:
try:
value = pobj.datatype(attrs[pname])
except BadValueError:
raise ProgrammingError('parameter %s can not be set to %r'
% (pname, attrs[pname]))
newtype.accessibles[pname] = Override(default=value).apply(pobj)
# check validity of Parameter entries
for pname, pobj in newtype.accessibles.items():
# XXX: create getters for the units of params ??
# wrap of reading/writing funcs
if isinstance(pobj, Command):
# skip commands for now
continue
rfunc = attrs.get('read_' + pname, None)
rfunc_handler = pobj.handler.get_read_func(newtype, pname) if pobj.handler else None
if rfunc_handler:
if rfunc:
raise ProgrammingError("parameter '%s' can not have a handler "
"and read_%s" % (pname, pname))
rfunc = rfunc_handler
else:
for base in bases:
if rfunc is not None:
break
rfunc = getattr(base, 'read_' + pname, None)
# create wrapper except when read function is already wrapped
if rfunc is None or getattr(rfunc, '__wrapped__', False) is False:
def wrapped_rfunc(self, pname=pname, rfunc=rfunc):
if rfunc:
self.log.debug("calling %r" % rfunc)
try:
value = rfunc(self)
self.log.debug("rfunc(%s) returned %r" % (pname, value))
if value is Done: # the setter is already triggered
return getattr(self, pname)
except Exception as e:
self.log.debug("rfunc(%s) failed %r" % (pname, e))
self.announceUpdate(pname, None, e)
raise
else:
# return cached value
self.log.debug("rfunc(%s): return cached value" % pname)
value = self.accessibles[pname].value
setattr(self, pname, value) # important! trigger the setter
return value
if rfunc:
wrapped_rfunc.__doc__ = rfunc.__doc__
setattr(newtype, 'read_' + pname, wrapped_rfunc)
wrapped_rfunc.__wrapped__ = True
if not pobj.readonly:
wfunc = attrs.get('write_' + pname, None)
if wfunc is None: # ignore the handler, if a write function is present
wfunc = pobj.handler.get_write_func(pname) if pobj.handler else None
for base in bases:
if wfunc is not None:
break
wfunc = getattr(base, 'write_' + pname, None)
# create wrapper except when write function is already wrapped
if wfunc is None or getattr(wfunc, '__wrapped__', False) is False:
def wrapped_wfunc(self, value, pname=pname, wfunc=wfunc):
self.log.debug("check validity of %s = %r" % (pname, value))
pobj = self.accessibles[pname]
value = pobj.datatype(value)
if wfunc:
self.log.debug('calling %s %r(%r)' % (wfunc.__name__, wfunc, value))
returned_value = wfunc(self, value)
if returned_value is Done: # the setter is already triggered
return getattr(self, pname)
if returned_value is not None: # goodie: accept missing return value
value = returned_value
setattr(self, pname, value)
return value
if wfunc:
wrapped_wfunc.__doc__ = wfunc.__doc__
setattr(newtype, 'write_' + pname, wrapped_wfunc)
wrapped_wfunc.__wrapped__ = True
def getter(self, pname=pname):
return self.accessibles[pname].value
def setter(self, value, pname=pname):
self.announceUpdate(pname, value)
setattr(newtype, pname, property(getter, setter))
# check information about Command's
for attrname in attrs:
if attrname.startswith('do_'):
if attrname[3:] not in newtype.accessibles:
raise ProgrammingError('%r: command %r has to be specified '
'explicitly!' % (name, attrname[3:]))
attrs['__constructed__'] = True
return newtype
@property
def configurables(cls):
# note: this ends up as an property of the Module class (not on the instance)!
# dict of properties with Property and Parameter with dict of properties
res = {}
# collect info about properties
for pn, pv in cls.properties.items():
if pv.settable:
res[pn] = pv
# collect info about parameters and their properties
for param, pobj in cls.accessibles.items():
res[param] = {}
for pn, pv in pobj.getProperties().items():
if pv.settable:
res[param][pn] = pv
return res