Re: Private members of ref counted classes and lambdas
On 06/04/2015 07:29 AM, Andrew Osmond wrote: Suppose I have some ref counted class Foo with the private member mBar. Normally with a lambda expression, [...] obviously the Foo object could get released before the dispatch completes You may be interested in this thread from a few months back: Proposal to ban the usage of refcounted objects inside C++ lambdas in Gecko https://groups.google.com/d/msg/mozilla.dev.platform/Ec2y6BWKrbM/xpHLGwJ337wJ (Not sure it arrived at a concrete conclusion, but you may run across some pitfalls/suggestions at least. I haven't used lambdas in C++, so I won't attempt to directly answer your question.) ~Daniel ___ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
Re: Private members of ref counted classes and lambdas
On Jun 4, 2015, at 11:17 AM, Daniel Holbert dholb...@mozilla.com wrote: You may be interested in this thread from a few months back: Proposal to ban the usage of refcounted objects inside C++ lambdas in Gecko https://groups.google.com/d/msg/mozilla.dev.platform/Ec2y6BWKrbM/xpHLGwJ337wJ (Not sure it arrived at a concrete conclusion, but you may run across some pitfalls/suggestions at least. I haven't used lambdas in C++, so I won't attempt to directly answer your question.) My impression was that the conclusion was “refcounted objects are not banned inside C++ lambdas” - i.e., no policy change from the status quo - but we need to be aware of the pitfalls”. The pitfalls are discussed pretty thoroughly in the thread. - Seth ___ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
Re: Private members of ref counted classes and lambdas
Turns out my original problem was some other mistake I made. Using just self works (thanks botond for the poke on IRC about that). I remember reading the linked thread, although I had since forgotten about it -- thanks for the reminder. My impression was that using raw pointers for ref counted objects with lambdas is something to be discouraged, rightfully so. That's why I use nsRefPtr, just like I would if I explicitly used a nested class inheriting from nsRunnable instead of a lambda. I'll review the thread again though (I *did* forgot about using Move, perhaps other bits as well). On Thu, Jun 4, 2015 at 2:24 PM, Seth Fowler s...@mozilla.com wrote: On Jun 4, 2015, at 11:17 AM, Daniel Holbert dholb...@mozilla.com wrote: You may be interested in this thread from a few months back: Proposal to ban the usage of refcounted objects inside C++ lambdas in Gecko https://groups.google.com/d/msg/mozilla.dev.platform/Ec2y6BWKrbM/xpHLGwJ337wJ (Not sure it arrived at a concrete conclusion, but you may run across some pitfalls/suggestions at least. I haven't used lambdas in C++, so I won't attempt to directly answer your question.) My impression was that the conclusion was “refcounted objects are not banned inside C++ lambdas” - i.e., no policy change from the status quo - but we need to be aware of the pitfalls”. The pitfalls are discussed pretty thoroughly in the thread. - Seth ___ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
Re: Private members of ref counted classes and lambdas
On Thu, Jun 4, 2015 at 2:24 PM, Seth Fowler s...@mozilla.com wrote: My impression was that the conclusion was “refcounted objects are not banned inside C++ lambdas” - i.e., no policy change from the status quo - but we need to be aware of the pitfalls”. The pitfalls are discussed pretty thoroughly in the thread. Capturing of raw pointers to refcounted objects was in fact banned - a static analysis forbidding it was introduced in bug 1153304. (Note that, as I discovered recently, the static analysis was over-eager and was also complaining about raw pointers to refcounted object being taken as an argument or used as a local variable inside a lambda - I'm about to land a fix for that in bug 1170388). Cheers, Botond ___ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
