[Python-Dev] PEP 342 support for string exceptions in throw() (original) (raw)

Phillip J. Eby pje at telecommunity.com
Fri Mar 24 23:24:09 CET 2006

Should geniter.throw() issue a deprecation warning for string exceptions?

My first thought was yes, since that's what raise() does.

On the other hand, one of the key motivating uses for throw() is to allow exception propagation on a coroutine stack. In this use case, the original "raise" of the string exception is what should be warned about. Issuing a warning for the line of code calling "throw()" is misleading, since that is not the line that is "wrong".

So, here's what I propose to do instead. Rather than support arbitrary string exceptions, which are deprecated anyway, they should only be allowed in the case where a non-None traceback argument is provided. Thus, string exceptions could be propagated using throw(), but not initiated.

Meanwhile, if you throw() a string exception with no traceback argument, you would receive the same error you do now.

Any objections?

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