PyProtocols API Reference

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PyProtocols API Reference |
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### Fixes and changes since PyProtocols 0.9.3 release candidate 1 Fixed a missing import problem in the version of `adapt()` used when PyProtocols is built using the `--without-speedups` option, as reported by Matthew Scott. ### Fixes and changes since PyProtocols 0.9.2 Adapter factories are now only called with one argument: the object to adapt. For backward compatibility, any adapter factories that require more than one argument are wrapped in a converter. It's highly recommended that you transition to one-argument adapters as soon as practical, since using two-argument adapters will cause deprecation warnings in PyProtocols version 1.0 (and causes PendingDeprecationWarnings in 0.9.3). This change was made for symmetry with Zope and Twisted adapters, as well as Pythonic adapter factories like `int` et al. The `factory` parameter to `adapt()` is DEPRECATED. An informal survey of PyProtocols' users indicated that nobody was using it to any significant degree, and its removal was unopposed. This feature was an extension to PEP 246, so this brings PyProtocols into closer conformance with the PEP. If you are currently using it, you will receive a `DeprecationWarning`, and in PyProtocols 1.0 your code will break. Fixed `protocols.sequenceOf()` being unable to directly imply a non-sequence protocol. Raise `AdaptationFailure` instead of `NotImplementedError` when adaptation is unsuccessful. `AdaptationFailure` is a subclass of both `TypeError` and `NotImplementedError`, so code written according to either PEP 246 or older versions of PyProtocols will still catch the error. There is now an `AbstractBase` class, similar to `Interface`, that can be used for the "ABC" (Abstract Base Class) style of interface usage, where the interface may contain implementation code, and can be subclassed to create concrete implementations. In previous versions, you could use `Interface` as such a base class, but now calling an `Interface` object performs adaptation rather than instantiation, unless the subclass redefines `__init__`. `Protocol` instances (except for `AbstractBase` subclasses) are now callable with a signature similar to `adapt()`. E.g. 'ISomething(foo,args)' is equivalent to 'adapt(foo,ISomething,args)'. This convenient API, pioneered by Twisted and later adopted by Zope X3, is now available in PyProtocols as well. (Note that as a result of this change, the PyProtocols test suite now requires a Zope X3 alpha release or better.) `setup.py` now accepts a `--without-speedups` global option to disable the C speedups module. We now support the latest `adapter_hooks` protocol provided by Zope X3 interfaces, allowing multiple interface registry systems to participate in Zope interfaces' `__adapt__()` implementation. Declaring an adapter from an instance to a protocol that was part of a circular implication path resulted in infinite recursion. Correcting the problem required a change in the return signature of the `declareProvides()` method in the `IOpenProvider` interface. Please see the docstring or the updated reference manual for details. Thanks to Bob Ippolito for discovering the problem and bringing it to my attention. Defining an adapter from one protocol to another, when that adapter does not shorten the adaptation path, would produce a spurious `KeyError`. ### Fixes since PyProtocols 0.9.1 Fixed missing unit tests for `Variation` class, and the two bugs in `Variation` that weren't found because of the missing tests. ### Fixes and Enhancements since PyProtocols 0.9 Added the `factoryMethod` and `equivalentProtocols` keywords to `advise()`. Added `sequenceOf()`, allowing you to easily create a protocol that represents a sequence of some base protocol, and automatically adapt basic sequences (e.g. lists and tuples) to a "sequence of" the base protocol, as long as all members of the input sequence can be adapted to the base protocol. By default, only lists and tuples are considered to support `IBasicSequence`. Added `protocolForType()` and `protocolForURI()`, that allow you to link interfaces by intended semantics, not just by having identical instances. For example, you can use `protocolForType(file,["read"])` to symbolize a file-like object with a `read()` method, or `protocolForURI("some UUID")` to symbolize some documented interface. In addition to compact declarations, this also allows a module to refer to an interface without importing a specific definition of it. Then, when that module is used in a larger program, the linkage between the symbolic and actual forms of the interface can be accomplished semi-automatically. Enhanced Zope 3 support: Now, adapters can be registered between Zope interfaces, and any types or instances. Note, however, that interface-to-interface adaptation may not work if a class only declares what it implements using the Zope interface API. This limitation might be able to be removed later. Zope interfaces can now pass a much larger segment of the test suite than before. Added 'protocols.Variation(baseProtocol,context=None)'; this implements the `LocalProtocol` example in the documentation. Added `Adapter` and `StickyAdapter` convenience base classes. `Adapter` offers a ready-made `__init__()` method suitable for most adapter classes, while `StickyAdapter` instances automatically declare themselves as an instance-specific adapter for any object they're used on. Thus, a `StickyAdapter` can maintain its state across `adapt()` calls for the same object, so long as the object can have instance-specific adapters declared. (See "Protocol Declarations for Individual Objects" in the reference manual for more information on this.) Added experimental support for 'ExtensionClass'; previously, PyProtocols could raise bizarre errors and/or behave strangely when `adapt()` was called on `ExtensionClass` instances. Fixed some problems with the test suite when running under Python 2.3. PyProtocols itself worked fine, but the test suite was bitten by two minor semantic changes that took effect in 2.3, resulting in lots of error messages about ModuleType needing a parameter, and a test failure for `checkClassInfo` in the `FrameInfoTest` test class. Fixed a memory leak in the C "speedups" module that leaked unbound `__conform__` and `__adapt__` methods, as well as `__class__` and `__mro__` references. Also, fixed the C code potentially reraising invalid error tracebacks under certain circumstances.

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