9a2e25c370
- Enables a method of deriving Django settings from other Django settings after all other Django settings are stable.
70 lines
2.4 KiB
Python
70 lines
2.4 KiB
Python
"""
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Allows the registration of Django/Python settings that are derived from other settings
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via callable methods/lambdas. The derivation time can be controlled to happen after all
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other settings have been set. The derived setting can also be overridden by setting the
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derived setting to an actual value.
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"""
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import six
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import sys
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# Global list holding all settings which will be derived.
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__DERIVED = []
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def derived(*settings):
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"""
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Registers settings which are derived from other settings.
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Can be called multiple times to add more derived settings.
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Args:
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settings (list): List of setting names to register.
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"""
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__DERIVED.extend(settings)
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def derived_dict_entry(setting_dict, key):
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"""
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Registers a setting which is a dictionary and needs a derived value for a particular key.
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Can be called multiple times to add more derived settings.
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Args:
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setting_dict (str): Name of setting which contains a dictionary.
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key (str): Name of key in the setting dictionary which will be derived.
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"""
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__DERIVED.append((setting_dict, key))
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def derive_settings(module_name):
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"""
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Derives all registered settings and sets them onto a particular module.
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Skips deriving settings that are set to a value.
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Args:
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module_name (str): Name of module to which the derived settings will be added.
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"""
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module = sys.modules[module_name]
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for derived in __DERIVED:
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if isinstance(derived, six.string_types):
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setting = getattr(module, derived)
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if callable(setting):
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setting_val = setting(module)
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setattr(module, derived, setting_val)
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elif isinstance(derived, tuple):
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# If a tuple, two elements are expected - else ignore.
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if len(derived) == 2:
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# Both elements are expected to be strings.
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# The first string is the attribute which is expected to be a dictionary.
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# The second string is a key in that dictionary containing a derived setting.
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setting = getattr(module, derived[0])[derived[1]]
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if callable(setting):
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setting_val = setting(module)
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getattr(module, derived[0]).update({derived[1]: setting_val})
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def clear_for_tests():
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"""
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Clears all settings to be derived. For tests only.
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"""
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global __DERIVED
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__DERIVED = []
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