1437606 - tidy up QI implementations in libpref

Status: RESOLVED FIXED

(Core :: Preferences: Backend, enhancement)

Comment 1

[Nathan Froyd [:froydnj]]

Attachment: part 1 - use NS_IMPL_QUERY_INTERFACE in modules/libpref/

This construct is nicer than NS_INTERFACE_MAP_BEGIN and assures the
reader there's no weirdness in the QI implementation.  This change does
mean that PGO doesn't get an opportunity to measure the frequency of
which interfaces are QI'd most often.  I think this is probably an OK
tradeoff to make, given the prevalence of NS_IMPL_QUERY_INTERFACE
elsewhere in the codebase.

The one thing we have to ensure with this change is that the ambiguous
QI to nsISupports uses the proper class after the change.  The
NS_IMPL_QUERY_INTERFACE macro chooses the first interface listed to
disambiguate the cast to nsISupports.

Comment 2

[Nathan Froyd [:froydnj]]

Attachment: part 2 - use NS_IMPL_ISUPPORTS in modules/libpref/

Now that we've used the standard NS_IMPL_QUERY_INTERFACE macro, we can
start using the even more standard NS_IMPL_ISUPPORTS macro.

Comment 3

[Nicholas Nethercote [inactive]]

Comment on attachment 8950293 [details] [diff] [review]
part 2 - use NS_IMPL_ISUPPORTS in modules/libpref/

Review of attachment 8950293 [details] [diff] [review]:
-----------------------------------------------------------------

This is one case where I think folding the two patches together would make them easier to understand :)

Comment 4

[Nathan Froyd [:froydnj]]

(In reply to Nicholas Nethercote [:njn] from comment #3)
> This is one case where I think folding the two patches together would make
> them easier to understand :)

Maybe so.  For the xpconnect version (bug 1437605), it seemed easier to split them up, because it was easier to verify that the ambiguous nsISupports cast was in the right place.  But I guess here, that was less of a concern.

Comment 5

[Nicholas Nethercote [inactive]]

It's not a big deal either way.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/98c4ffa07c96
part 1 - use NS_IMPL_QUERY_INTERFACE in modules/libpref/; r=njn
https://hg.mozilla.org/integration/mozilla-inbound/rev/0541e57dfa18
part 2 - use NS_IMPL_ISUPPORTS in modules/libpref/; r=njn

Comment 7

[Dorel Luca [:dluca]]

https://hg.mozilla.org/mozilla-central/rev/98c4ffa07c96
https://hg.mozilla.org/mozilla-central/rev/0541e57dfa18