1312319 - Add a NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING macro for pure virtual AddRef/Release functions

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[Kartikaya Gupta (email:[e-mail])]

What appears to be a common pattern in the code [1] is to have an "interface" type of class (with pure virtual methods) and allow RefPtrs to this interface. That requires having pure virtual AddRef/Release functions on the interface. It would be nice to have a macro that expands to this:

NS_IMETHOD_(MozExternalRefCountType) AddRef(void) = 0;
NS_IMETHOD_(MozExternalRefCountType) Release(void) = 0;

for use in such classes. Not sure if this belongs in MFBT or XPCOM glue. Classes that inherit from this interface can use one of the existing macros to provide an implementation of these functions, or can inherit the implementation from some other base class.

[1] See how many of the results in e.g. http://searchfox.org/mozilla-central/search?q=NS_IMETHOD_(MozExternalRefCountType)&case=false&regexp=false&path= have pure virtual functions.

Comment 1

[Kartikaya Gupta (email:[e-mail])]

Bump. I was just about to file this bug again but it looks like I already filed it :)

Does anybody have objections to this?

Comment 2

[Kartikaya Gupta (email:[e-mail])]

There's even a name suggested at [1]: NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING

[1] http://searchfox.org/mozilla-central/rev/bf98cd4315b5efa1b28831001ad27d54df7bbb68/dom/flyweb/HttpServer.h#38

Comment 3

[Botond Ballo [:botond]]

No objection from me!

Comment 4

[Kartikaya Gupta (email:[e-mail])]

Try push in progress: https://treeherder.mozilla.org/#/jobs?repo=try&revision=d3bf6bd5d41b4b4e3dc8cfb1c5aef1bffbd7e1db

Comment 5

[Kartikaya Gupta (email:[e-mail])]

Attachment: Bug 1312319 - Add a NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING macro and replace existing pure-virtual AddRef/Release declarations.

Review commit: https://reviewboard.mozilla.org/r/107218/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/107218/

Comment 6

[Nathan Froyd [:froydnj]]

Comment on attachment 8830465 [details]
Bug 1312319 - Add a NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING macro and replace existing pure-virtual AddRef/Release declarations.

https://reviewboard.mozilla.org/r/107218/#review108616

Thanks for cleaning this up.  Have to say that I'm kind of impressed that everybody declared it more-or-less the same way prior to this patch.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/ff0000b808c5
Add a NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING macro and replace existing pure-virtual AddRef/Release declarations. r=froydnj

Comment 8

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/ff0000b808c5