AMDG On 07/26/2012 02:57 AM, Christophe Henry wrote:
Hi all,
here's my review for TypeErasure.
Thank you very much for your review.
Please state clearly whether you think this library should be accepted as a Boost library.
Let's answer this upfront: YES!
Other questions you may want to consider: 1. What is your evaluation of the design?
Seen from outside, the design is clean and allows powerful constructs.
2. What is your evaluation of the implementation?
I only had a quick glance.
3. What is your evaluation of the documentation?
What is there is very good, but we could do with more documentation. A few suggestions: - provide a small example of usage of each concept to help new users manage faster the learning curve. I had some difficulties getting istreamable working and had to look at the tests to finally get it.
Okay.
- provide more real-looking examples of the sort of the polymorphic range formatter. The more the better. I'll myself provide one later on in this message.
4. What is your evaluation of the potential usefulness of the library?
Huge! And by this I mean a very interesting programming style which should be made available also to average programmers. Which makes the doc even more important.
5. Did you try to use the library? With what compiler? Did you have any problems?
Yes, on a real private project I do on my free time. I used VC9. I'm in vacations so I couldn't try gcc and VC10 yet but I'll do this in the next few weeks. I got no problem besides a single warning about unused variable (fixed).
Good to hear.
I tried the library for 2 different use cases: - a streamable any (actually I need a boost-serializable any but didn't come to it yet). One always needs something like this. In the past, I had to modify a Boost.Any to achieve this. In my design, this helps implement my low-level saving/loading to/from file easily as the low level layer needs no knowledge about the types it gets, they're just a bunch of serializable things.
- improve my MVC (Model-View-Controller) design. Here's my use case: I started with a classical (OO style) interface-based design a graphical editor where the user can place and edit items of different kinds on a drawing area. The interface for these items is something along the lines: <snip example>
This looks great. I'll work this into a complete example.
There is only one thing missing to be able to throw away all these interfaces: the ability to navigate through dynamic/static cast in the hierarchy. TypeErasure supports upcasting of concepts but not downcasting. According to Steven, this would be possible. I won't make it an acceptance condition, but I could make good use of this feature. My use case: different view items get an IItem, then a view Item for Type1 would safely cast down its IItem to IType1. This is at the moment not possible with TypeErasure. I view this as a killer feature, so I can only advise providing it at a later point.
I hadn't considered this very important, but you're the second person to request this, so I'll bump up it's priority.
One last request: I would like the possibility to read the concept of an any through a metaprogram. I found this: /** INTERNAL ONLY */ typedef Concept _boost_type_erasure_concept_type;
I try to avoid using internals, could this be made part of the public interface?
This is provided as a metafunction concept_of. In Christ, Steven Watanabe