On 09/14/2017 02:50 AM, Peter Xu wrote: > Then I can get NULL rather than crash when calling things like: > > qstring_get_str(qobject_to_qstring(object)); > > when key does not exist.
Right now, qdict_get_str() is documented as:
* This function assumes that 'key' exists and it stores a
* QString object.
Your code changes that, by making it now return NULL instead of crashing
on what used to be usage in violation of the contract; compared to
qdict_get_try_str() which gracefully returns NULL, but which could use
your new semantics for doing so in fewer lines of code.
I'm not necessarily opposed to the change, but I worry that it has
subtle ramifications that we haven't thought about, as well as
consistency with the rest of the QObject APIs. It may be better to just
introduce qstring_get_try_str(), which gracefully handles NULL input,
and leave the existing function alone; and if you do introduce a new
helper, it may be worth converting existing clients (perhaps with help
from Coccinelle) to take advantage of the helper.
> +++ b/qobject/qstring.c
> @@ -125,7 +125,7 @@ QString *qobject_to_qstring(const QObject *obj)
> */
> const char *qstring_get_str(const QString *qstring)
> {
> - return qstring->string;
> + return qstring ? qstring->string : NULL;
> }
>
> /**
>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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