Re: [Boost-users] [Review] ITL review starts today, February 18th

Subject: Re: [Boost-users] [Review] ITL review starts today, February 18th
From: Jeff Flinn (TriumphSprint2000_at_[hidden])
Date: 2010-03-08 10:28:04

> Please always state in your review, whether you think the library should be
> accepted as a Boost library.

Yes, I think the library (with the interface improvements brought out 
during the review) should be accepted into boost. I've already 
successfully used the library with it's existing interface in a 
commercial product.

> - What is your evaluation of the design?

As brought up during the course of the review period my main concerns 
for the library's interface are:

1) the bloated size of the interval class with it's dynamic bound data 
member. This is being addressed by Joachim providing an interface to 
allow use of static bound interval classes.

2) the fat interface on the interval class. In my view the myriad of 
mutators would best be replaced with free functions in terms of the 
interval's extents and return a interval passing the calculated extents 
to an interval constructor which enforces the interval's invariant(s). 
There should also be a method to construct an interval given unordered 
extents that effectively does interval(min(arg1, arg2), max(arg1, arg2)).

3) better integration of std and user defined data types en lieu of 
itl's specific types. Joachim has agreed to improvements in this area.

4) I'd also like to see std::inserter "just work" with the containers. I 
shouldn't have to expect to look for the itl specific adder to do this. 
This was the most common usage my applications had for populating 
interval containers using std::copy/transform from my applications 
existing data structures.

> - What is your evaluation of the implementation?

Seems adequate. I was able to port to the portions I needed to 
CodeWarrior 9.4 (from 2003?). IIRC, Joachim integrated the 
changes(simplifications) that allowed itl to work in this environment.

Performance for the scale of problems I've been dealing with were fine, 
but as has been discussed scaling to larger sizes of millions of items 
may require some specialized containers. I don't see this as a problem, 
it's analogous to std::map and std::unordered_map.

Hmm, It just occurs to me that for my application I could void the N^2 
size issue of a split_interval_map<int, set<> > with a 
non_combining_map<int, data> that allowed me to iterate through all 
items that overlap with an arbitrary interval in and ordered fashion. 
That's not much different from a std::map<interval, data>, but with some 
more interval specific wrapping of the upper/lower_bound/equal_range 
methods.

> - What is your evaluation of the documentation?

I was able to get up and running fairly quickly. As discussed some of 
the colorful terminology got in the way rather than helping. Also I had 
expected to just be able to populate with std::inserter, and had trouble 
finding docs related to this. The example for copy/transform helped, but 
even during this review I have trouble finding the docs for 
itl::adder/inserter.

> - What is your evaluation of the potential usefulness of the library?

Very, I've come across needs for this capability in 3 different jobs in 
3 very different industries. I've had domain specific solutions and was 
looking to create just such a generic library when Joachim submitted his 
library.

> - Did you try to use the library?  With what compiler?  Did you have any
> problems?

Yes, the library is being used in a commercial application built with 
CodeWarrior 9.4 on Mac/Windows and with VC8 and XCode 3.x. The library 
required some modifications to the template declarations for CodeWarrior.

> - How much effort did you put into your evaluation? A glance? A quick
> reading? In-depth study?

I read through the documentation, integrated the library with production 
code, dug through compilation error messages and headers on CodeWarrior 
to port a portion of the library. I've profiled code using itl to 
understand performance implications.

> - Are you knowledgeable about the problem domain?

Yes, I've designed/implemented/optimized integral open-closed Interval 
and IntervalSet classes for use in previous projects.

Jeff