Re: [Qemu-devel] [PATCH v2] Revised: Add object_property_get_child().

["Andreas Färber" <afaerber@suse.de>]

Am 19.02.2012 17:04, schrieb Alexander Barabash:
> 
>     Add object_property_get_child().
> 
>     Adding a direct accessor to a child property.
> 
>     In the existing implementation, object_property_get() must be used,
>     with with a visitor, implementing the 'type_str' callback,
>     receiving the child's canonical path.
> 
>     In the new implementation, the child is returned directly.
>     For link properties, object_property_get_link() is used
>     to resolve the link.
> 
>     Also, in the new implementation, object_property_get_child() is used
>     as a subroutine of object_resolve_abs_path(). This changes the way
>     object_resolve_abs_path() operates, moving away from directly peeking
>     the property's 'opaque' field to using object_property_get_link().
> 
>     Thus, in the mew implementation link properties are resolved in the
> same way,
>     as they are when an absolute path is resolved.
> 
>     Errors relevant to the operation, QERR_OBJECT_PROPERTY_NOT_FOUND
>     and QERR_OBJECT_PROPERTY_INVALID_TYPE were added.
> 
>     Also, in the new implementation, some common sense refactoring was done
>     in the file 'qom/object.c' in the code extracting child and link
> properties.
> 
>     Signed-off-by: Alexander Barabash <alexander_barabash@mentor.com>

Please use git-send-email to submit your patches: The commit message is
unnecessarily indented and the first line is duplicated. Instead of
"Revised: " (which v2 already indicates) the subject should mention the
topic, here "qom: ".

http://wiki.qemu.org/Contribute/SubmitAPatch

Your patch is doing too many things at once. Please split it up into a
series of easily digestable and bisectable patches, e.g.:
* ..._PREFIX/SUFFIX introduction and use in _add_child/link,
* ..._is_child/_is_link introduction and use in
_property_del_child/_get_canonical_path/_resolve_partial_path,
* link_type_to_type() and use in _set_link_property,
* REPORT_OBJECT_ERROR(),
* object_property_get_child().

> +/* Go from LINK_PROPERTY_TYPE_PREFIX FOO LINK_PROPERTY_TYPE_SUFFIX to
> FOO.  */
> +static gchar *link_type_to_type(const gchar *type)
> +{
> +    return g_strndup(&type[sizeof(LINK_PROPERTY_TYPE_PREFIX) - 1],
> +                     strlen(type)
> +                     - (sizeof(LINK_PROPERTY_TYPE_PREFIX) - 1)
> +                     - (sizeof(LINK_PROPERTY_TYPE_SUFFIX) - 1));

Any reason not to use strlen()? I don't think this is a hot path, and
repeated sizeof() - 1 does not read so nice. The alternative would be to
hardcode the offsets.

Andreas

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