Source code for apache_beam.options.value_provider

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"""A ValueProvider class to implement templates with both statically
and dynamically provided values.

from functools import wraps

from apache_beam import error

__all__ = [

[docs]class ValueProvider(object):
[docs] def is_accessible(self): raise NotImplementedError( 'ValueProvider.is_accessible implemented in derived classes' )
[docs] def get(self): raise NotImplementedError( 'ValueProvider.get implemented in derived classes' )
[docs]class StaticValueProvider(ValueProvider): def __init__(self, value_type, value): self.value_type = value_type self.value = value_type(value)
[docs] def is_accessible(self): return True
[docs] def get(self): return self.value
def __str__(self): return str(self.value)
[docs]class RuntimeValueProvider(ValueProvider): runtime_options = None def __init__(self, option_name, value_type, default_value): self.option_name = option_name self.default_value = default_value self.value_type = value_type
[docs] def is_accessible(self): return RuntimeValueProvider.runtime_options is not None
[docs] def get(self): if RuntimeValueProvider.runtime_options is None: raise error.RuntimeValueProviderError( '%s.get() not called from a runtime context' % self) candidate = RuntimeValueProvider.runtime_options.get(self.option_name) if candidate: value = self.value_type(candidate) else: value = self.default_value return value
[docs] def set_runtime_options(cls, pipeline_options): RuntimeValueProvider.runtime_options = pipeline_options
def __str__(self): return '%s(option: %s, type: %s, default_value: %s)' % ( self.__class__.__name__, self.option_name, self.value_type.__name__, repr(self.default_value) )
[docs]def check_accessible(value_provider_list): """Check accessibility of a list of ValueProvider objects.""" assert isinstance(value_provider_list, list) def _check_accessible(fnc): @wraps(fnc) def _f(self, *args, **kwargs): for obj in [getattr(self, vp) for vp in value_provider_list]: if not obj.is_accessible(): raise error.RuntimeValueProviderError('%s not accessible' % obj) return fnc(self, *args, **kwargs) return _f return _check_accessible