[Python-Dev] New syntax for 'dynamic' attribute access

["Martin v. Löwis"]

Brett Cannon schrieb:
>         name = 'open_' + urltype
>         self.type = urltype
>         name = name.replace('-', '_')
>         if not hasattr(self, name):
>             if proxy:
>                 return self.open_unknown_proxy(proxy, fullurl, data)
>             else:
>                 return self.open_unknown(fullurl, data)
>         try:
>             if data is None:
>                 return self.(name)(url)
>             else:
>                 return self.(name)(url, data)
>         except socket.error, msg:
>             raise IOError, ('socket error', msg), sys.exc_info()[2]

Also notice that this leaves a hasattr call in, as there is no 
replacement proposed for that.

>         name = 'http_error_%d' % errcode
>         if hasattr(self, name):
>             method = self.(name)
>             if data is None:
>                 result = method(url, fp, errcode, errmsg, headers)
>             else:
>                 result = method(url, fp, errcode, errmsg, headers, data)
>             if result: return result
>         return self.http_error_default(url, fp, errcode, errmsg, headers)

Likewise.

>         if attr[:12] == '_Request__r_':
>             name = attr[12:]
>             if hasattr(Request, 'get_' + name):
>                 self.['get_' + name]()
>                 return self.[attr]
>         raise AttributeError, attr

And again. Apparently, people favor hasattr over catching 
AttributeError. I'm not sure why this is - I would probably
rewrite them all to deal with AttributeError if I use the new
syntax in the first place.


Regards,
Martin