65 lines
2.1 KiB
ReStructuredText
65 lines
2.1 KiB
ReStructuredText
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Differences with Python
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=======================
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* ``py.js`` completely ignores old-style classes as well as their
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lookup details. All ``py.js`` types should be considered matching
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the behavior of new-style classes
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* New types can only have a single base. This is due to ``py.js``
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implementing its types on top of Javascript's, and javascript being
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a single-inheritance language.
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This may change if ``py.js`` ever reimplements its object model from
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scratch.
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* Piggybacking on javascript's object model also means metaclasses are
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not available (:js:func:`py.type` is a function)
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* A python-level function (created through :js:class:`py.PY_def`) set
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on a new type will not become a method, it'll remain a function.
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* :js:func:`py.PY_parseArgs` supports keyword-only arguments (though
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it's a Python 3 feature)
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* Because the underlying type is a javascript ``String``, there
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currently is no difference between :js:class:`py.str` and
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:js:class:`py.unicode`. As a result, there also is no difference
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between :js:func:`__str__` and :js:func:`__unicode__`.
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Unsupported features
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--------------------
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These are Python features which are not supported at all in ``py.js``,
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usually because they don't make sense or there is no way to support them
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* The ``__delattr__``, ``__delete__`` and ``__delitem__``: as
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``py.js`` only handles expressions and these are accessed via the
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``del`` statement, there would be no way to call them.
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* ``__del__`` the lack of cross-platform GC hook means there is no way
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to know when an object is deallocated.
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* ``__slots__`` are not handled
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* Dedicated (and deprecated) slicing special methods are unsupported
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Missing features
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----------------
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These are Python features which are missing because they haven't been
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implemented yet:
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* Class-binding of descriptors doesn't currently work.
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* Instance and subclass checks can't be customized
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* "poor" comparison methods (``__cmp__`` and ``__rcmp__``) are not
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supported and won't be falled-back to.
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* ``__coerce__`` is currently supported
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* Context managers are not currently supported
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* Unbound methods are not supported, instance methods can only be
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accessed from instances.
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