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February 2017

82 participants
62 discussions

Re: [boost] Is there any interest in non-owning pointer-like types?
by Joseph Thomson 01 Feb '17

01 Feb '17

On 1 Feb 2017 7:51 p.m., "Olaf van der Spek" <ml(a)vdspek.org> wrote: On Wed, Feb 1, 2017 at 12:39 PM, Oswin Krause <Oswin.Krause(a)ruhr-uni-bochum.de> wrote: > On 2017-02-01 12:02, Olaf van der Spek wrote: >> >> On Wed, Feb 1, 2017 at 11:24 AM, Oswin Krause >> <Oswin.Krause(a)ruhr-uni-bochum.de> wrote: >>> >>> For me, the biggest problem of the proposal is that observer_ptr<T> is >>> implicitely constructed from T&. In my code I often use: >>> >>> Foo a; >>> Bar b(&a);//&a signals that b only references to a, but does not copy it. >>> >>> Now, when I write >>> >>> Bar b(a); //so is a now copied? >>> >>> While the interface is clearer in documentation, the usage is less clear! >> >> >> IMO using pointers instead of references to indicate something isn't >> copied is bad practice.. the language is C++, not C. > > > > This is not a C vs C++ thing. > > But assume it was. How would you indicate that in C++? It should be clear > without looking at the reference whether it is okay for a to go out of scope > before b or not. There's no way to indicate that, AFAIK. The way to indicate it is to require explicit conversion from `T&` to your pointer-like type. `make_observer` can play the role of a type-safe `&`. I would be happy to remove implicit conversion from `T&` if it is agreed to be undesirable. Joseph

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Re: [boost] Boost XML Serialization Stability across library versions
by Adlai Shawareb 01 Feb '17

01 Feb '17

Thanks Robert, Regarding your suggestion to use text serialization. Since, over time, we will be adding and deleting data from the data set that we serialize, would the following be the right approach to managing the changes in the data that is de/serialized. I'm thinking that we would set the BOOST_CLASS_VERSION before de/serializing. { ar & mInt; If(version >= 2) ar & mFloat; If(version >= 3) ar & mInt2; ar & mFloat2; } Regards, Adlai On 1/25/17 12:04:00, Robert Ramey wrote: > Right. No one as under taken that task. Should be fairly straight > forward using spirit v3. > Robert Ramey

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