[Twisted-Python] Appropriate exception for AMP types receiving garbage?

[Glyph]

On Dec 26, 2012, at 1:43 PM, Laurens Van Houtven <_ at lvh.cc> wrote:

> I'm writing a custom AMP type. I noticed that when writing the unit test for garbage input, I didn't really know what exception to check for.
> 
> I couldn't find any place where this was formally defined, so I checked for implementation behavior. Boolean explicitly raises TypeError. Integer raises ValueError, but that appears to only be an implementation detail of int.
> 
> It could also be that it doesn't matter at all, but it does seem a little strange that Integer and Boolean raise different exceptions when fed garbage...

Hey Laurens,

This is basically a feature request :).  There's no particular defined error type for argument parse errors in AMP.  It's not a bad feature though.  The exception also doesn't go anywhere useful - the only contract is basically that it'll bubble up and break the connection if you get some bad data.  A more sophisticated and trappable / trackable way to propagate this sort of error would be useful.

(I would personally consider it a compatible change if the behavior of the error cases changed here, on the grounds that anything that uncontrollably logs a traceback in response to network input is a gross spec violation of a sort.  Maybe we should add an explicit exemption for that case.)

-glyph
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