Re: [PATCH v2 6/8] qom: introduce qdev_new_dynamic()

["Daniel P. Berrangé" <berrange@redhat.com>]

On Thu, Nov 14, 2024 at 03:47:20PM -0500, Peter Xu wrote:
> On Mon, Nov 11, 2024 at 03:55:53PM +0000, Daniel P. Berrangé wrote:
> > qdev_new() has a failure scenario where it will assert() if given
> > an abstract type. Callers which are creating qdevs based on user
> > input, or unknown/untrusted type names, must manually check the
> > result of qdev_class_is_abstract() before calling qdev_new()
> > to propagate an Error, instead of asserting.
> > 
> > Introduce a qdev_new_dynamic() method which is a counterpart to
> > qdev_new() that directly returns an Error, instead of asserting.
> > This new method is to be used where the typename is specified
> > dynamically by code separate from the immediate caller.
> > 
> > Do likewise with qdev_try_new_dynamic() as a counterpart to
> > qdev_try_new().
> 
> Since at it, would it make sense to simply replace qdev_try_new() with
> qdev_new_dynamic(), assuming it plays similar role of "it can fail" version
> of qdev_new()?

That is tricky as callers of qdev_try_new have to distinguish between
expected failures and unexpected failures.

That said you made me look at the usage patterns and I concluded these
xxx_try_new() methods are a bad design for other reasons, so I have
simply eliminated them entirely in v3.

With regards,
Daniel
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