[Twisted-Python] Unknown constants
Hi, I've been looking into using twisted.python.constants for representing the status codes of the XMPP Multi-User Chat protocol [1]. I will have objects representing messages, of which one of the attributes is 'mucStatuses', a set of status codes. This works out great for the initial set of available status codes. The protocol is parsed, and the status codes are represented by the ValueConstant instances returned by lookupByValue. However, not all of the possible codes can be known up-front, as the protocol allows for registering new ones without changing the specification itself. Eventually, applications will receive status codes that are not (yet?) part of the set of defined constants in the implementation, and application developers (that do know about new codes) will want to handle these. A possible remedy to would be to register new status codes from the application itself. My first try of just adding a new attribute to the class fails because they are not 'realized' as the _enumerants are cached. I can imagine this also goes for unknown HTTP methods and HTTP status codes, used as examples in the documentation. Any suggestions on how to handle such unknown constants? [1] <http://xmpp.org/extensions/xep-0045.html#statuscodes> -- ralphm
On Dec 26, 2011, at 12:21 PM, Ralph Meijer wrote:
Hi,
I've been looking into using twisted.python.constants for representing the status codes of the XMPP Multi-User Chat protocol [1]. I will have objects representing messages, of which one of the attributes is 'mucStatuses', a set of status codes. This works out great for the initial set of available status codes. The protocol is parsed, and the status codes are represented by the ValueConstant instances returned by lookupByValue.
However, not all of the possible codes can be known up-front, as the protocol allows for registering new ones without changing the specification itself. Eventually, applications will receive status codes that are not (yet?) part of the set of defined constants in the implementation, and application developers (that do know about new codes) will want to handle these.
A possible remedy to would be to register new status codes from the application itself. My first try of just adding a new attribute to the class fails because they are not 'realized' as the _enumerants are cached.
I can imagine this also goes for unknown HTTP methods and HTTP status codes, used as examples in the documentation. Any suggestions on how to handle such unknown constants?
twisted.python.constants is a work in progress; there are many planned features that it doesn't have yet. Perhaps you should simply add the feature that you want - the ability to adding new attributes to the class? -glyph
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Glyph -
Ralph Meijer