6cb62f2697
Please note that this is a squshed commit and the work of: Symbolist, macdiesel, nedbat, doctoryes, muzaffaryousaf and muhammad-ammar
81 lines
2.7 KiB
Python
81 lines
2.7 KiB
Python
"""
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Monkey-patch the edX platform
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Here be dragons (and simians!)
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* USE WITH CAUTION *
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No, but seriously, you probably never really want to make changes here.
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This module contains methods to monkey-patch [0] the edx-platform.
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Patches are to be applied as early as possible in the callstack
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(currently lms/startup.py and cms/startup.py). Consequently, changes
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made here will affect the entire platform.
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That said, if you've decided you really need to monkey-patch the
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platform (and you've convinced enough people that this is best
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solution), kindly follow these guidelines:
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- Reference django_18_upgrade.py for a sample implementation.
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- Name your module by replacing periods with underscores for the
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module to be patched:
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- patching 'django.utils.translation'
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becomes 'django_utils_translation'
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- patching 'your.module'
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becomes 'your_module'
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- Implement argumentless function wrappers in
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monkey_patch.your_module for the following:
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- is_patched
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- patch
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- unpatch
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- Add the following code where needed (typically cms/startup.py and
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lms/startup.py):
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```
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from monkey_patch import your_module
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your_module.patch()
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```
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- Write tests! All code should be tested anyway, but with code that
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patches the platform runtime, we must be extra sure there are no
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unintended consequences.
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[0] http://en.wikipedia.org/wiki/Monkey_patch
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"""
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# Use this key to store a reference to the unpatched copy
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__BACKUP_ATTRIBUTE_NAME = '__monkey_patch'
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def is_patched(module, attribute_name):
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"""
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Check if an attribute has been monkey-patched
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"""
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attribute = getattr(module, attribute_name)
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return hasattr(attribute, __BACKUP_ATTRIBUTE_NAME)
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def patch(module, attribute_name, attribute_replacement):
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"""
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Monkey-patch an attribute
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A backup of the original attribute is preserved in the patched
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attribute (see: __BACKUP_ATTRIBUTE_NAME).
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"""
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attribute = getattr(module, attribute_name)
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setattr(attribute_replacement, __BACKUP_ATTRIBUTE_NAME, attribute)
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setattr(module, attribute_name, attribute_replacement)
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return is_patched(module, attribute_name)
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def unpatch(module, attribute_name):
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"""
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Un-monkey-patch an attribute
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Restore a backup of the original attribute from the patched
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attribute, iff it exists (see: __BACKUP_ATTRIBUTE_NAME).
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Return boolean whether or not the attribute could be unpatched
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"""
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was_patched = False
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attribute = getattr(module, attribute_name)
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if hasattr(attribute, __BACKUP_ATTRIBUTE_NAME):
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attribute_old = getattr(attribute, __BACKUP_ATTRIBUTE_NAME)
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setattr(module, attribute_name, attribute_old)
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was_patched = True
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return was_patched
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