Object Mentor Blog: C++ Algorithms, Boost and function currying

C++ Algorithms, Boost and function currying

Brett Schuchert — Sat, 12 Jun 2010 23:41:00 -0500

I’ve been experimenting with C++ using the Eclipse CDT and gcc 4.4. Since I’m a fan of boost, I’ve been using that as well. I finally got into I realistic use of boost::bind.

I converted this:

int Dice::total() const {
  int total = 0;

  for(const_iterator current = dice.begin();
      current != dice.end();
      ++current)
    total += (*current)->faceValue();

  return total;
}

Into this:

int Dice::total() const {
  return std::accumulate(
      dice.begin(),
      dice.end(),
      0,
      bind(std::plus<int>(), _1, bind(&Die::faceValue, _2))
  );
}

To see how to go from the first version to the final version with lots of steps in between: http://schuchert.wikispaces.com/cpptraining.SummingAVector.

This is a first draft. I’ll be cleaning it up over the next few days. If you see typos, or if anything is not clear from the code, please let me know where. Also, if my interpretation of what boost is doing under the covers (there’s not much of that) is wrong, please correct me.

Thanks!

"C++ Algorithms, Boost and function currying" by UGG pas cher

Tue, 07 Sep 2010 03:45:04 -0500

Tout d’accord sur votre opinion. Et moi, aussi le fan de <a href=”http://www.uggbottessoldes.com”

target=”_blank”>bottes uggs, surtout sur sa doublure en laine. La marque

target=”_blank”>ugg bottes

. venait de trouver sa signature. En ce moment, vous pouvez pré-commander les

href=”http://www.uggbottessoldes.com” target=”_blank”>UGG Soldes

"C++ Algorithms, Boost and function currying" by dupont lighter

Sun, 05 Sep 2010 20:50:53 -0500

dupont lighter, dupont lighters, st dupont lighter, s.t. dupont lighters. Some actually seem like they are created with space creatures – not real women – in mind. But this fall, designers rolled out a multitude of great wearable looks.

"C++ Algorithms, Boost and function currying" by armani belt

Sun, 05 Sep 2010 20:50:10 -0500

armani belt, armani belts, armani belts for men, armani mens belt. Classic fashion styles are the looks that last through the ages and appear flattering on almost anyone. They go beyond trends and are a triumph of art. Despite the decade, figure or fashion, classic styles are always a demonstration of truly refined taste.

"C++ Algorithms, Boost and function currying" by Men’s belts

Sun, 05 Sep 2010 20:49:46 -0500

Men’s belts, LV men’s belts, Fashionable Gucci men’s belts, Attractive style Hermes men’s belts.
Today fashion and beauty can be affordable for everyone. There is always a range such as Avon that provides quality beauty, make up and accessory products at a prices most can afford. Mass fashion is moving so fast that fashion now moves in a weekly cycle and fashion trends are hot for a short time only.

"C++ Algorithms, Boost and function currying" by Hermes belt

Sun, 05 Sep 2010 20:49:18 -0500

Hermes belts, Elegant Hermes belt, Fashion Hermes belts for men, Hermes mens belt.
Today fashion and beauty can be affordable for everyone. There is always a range such as Avon that provides quality beauty, make up and accessory products at a prices most can afford. Mass fashion is moving so fast that fashion now moves in a weekly cycle and fashion trends are hot for a short time only.

"C++ Algorithms, Boost and function currying" by gucci wallet

Sun, 05 Sep 2010 20:48:55 -0500

gucci wallet, gucci wallets, mens gucci wallet, women gucci wallet.
The continually changing fashions of the West have been generally unparalleled either in antiquity or in the other great civilizations of the world until recent decades.

"C++ Algorithms, Boost and function currying" by louis vuitton wallet

Sun, 05 Sep 2010 20:48:38 -0500

louis vuitton wallet, louis vuitton wallets, mens louis vuitton wallet, women louis vuitton wallet.
Traditional country, Southwestern prints and modern city styles elegantly merge in a new collection of men’s-wear by Highland.

"C++ Algorithms, Boost and function currying" by supplynflshop

Tue, 31 Aug 2010 21:18:03 -0500

good post and thanks http://www.supplynflshop.com cheap nfl jerseys

"C++ Algorithms, Boost and function currying" by Leucadia Real Estate

Sun, 22 Aug 2010 11:06:25 -0500

I made that erroneous change and I had a failing unit test – so no thought experiment, I know with certainty that your subtle error isn’t so subtle at all……............

"C++ Algorithms, Boost and function currying" by Mission Hills Real Estate

Sat, 14 Aug 2010 12:16:47 -0500

I made that erroneous change and I had a failing unit test – so no thought experiment, I know with certainty that your subtle error isn’t so subtle at all…...............

"C++ Algorithms, Boost and function currying" by cosplay

Tue, 10 Aug 2010 21:27:21 -0500

The noblest search is the search for excellence

"C++ Algorithms, Boost and function currying" by lady dress

Tue, 20 Jul 2010 03:26:39 -0500

Wholesale clothing,fashion dress,lady dress,lady garment,lady fashion

"C++ Algorithms, Boost and function currying" by Halter

Mon, 19 Jul 2010 05:14:04 -0500

Sunshine of summer, the beautiful flower asperses full whole body, sweet and elegant breath, the circulation of the spread of elegant silk dress eyes from the waves to linger flying skirt . A gentle and graceful elasticity waist foil, more show delicate temperament of your daughter beauties.

"C++ Algorithms, Boost and function currying" by garments

Tue, 13 Jul 2010 21:17:24 -0500

clothing

"C++ Algorithms, Boost and function currying" by human

Mon, 12 Jul 2010 02:06:00 -0500

I do agree the syntax is a bit verbose and difficult which is a threshold for beginners, but I think/hope lambda expressions will help with that.

"C++ Algorithms, Boost and function currying" by Olivea Copper

Thu, 08 Jul 2010 05:59:27 -0500

Through my 27 years of infinite wisdom (my parents always said I was a smart-ass), I’ve learned a few things. Women, yea I consider myself an expert in the female area if you know what I mean (wink) – and the most important thing I’ve learned is to stay away from a woman on her PMS days. In fact, I’ve put together a few acronyms (abbreviations) based on my experience with the syndrome.

"C++ Algorithms, Boost and function currying" by http://www.laviesolar.com

Tue, 06 Jul 2010 03:20:39 -0500

Great web site. Than you for the information

"C++ Algorithms, Boost and function currying" by Birkenstock

Thu, 01 Jul 2010 22:45:54 -0500

thanks for your sharing, very good news.

"C++ Algorithms, Boost and function currying" by r9 irons

Tue, 29 Jun 2010 04:11:53 -0500

The noblest search is the search for excellence

"C++ Algorithms, Boost and function currying" by pump shoes

Tue, 29 Jun 2010 03:54:57 -0500

It seems that you have set many work in to your article and We require more of

those about the net presently. I truly got a drag out of one’s article. We do not

actually possess a lot in order to communicate reacting, I just wished to comment

in order to respond incredible perform

"C++ Algorithms, Boost and function currying" by cell phone headset

Tue, 29 Jun 2010 03:34:03 -0500

Nice one. I have stumbled and twittered this for my friends. Hope others find it as interesting as I did.

"C++ Algorithms, Boost and function currying" by galbur

Mon, 28 Jun 2010 07:57:38 -0500

the use of boost in this example is making for worse code.

"C++ Algorithms, Boost and function currying" by Peach

Fri, 25 Jun 2010 09:22:26 -0500

I also prefer the first version. I is an easy, clear code that works properly. I don’t think that the second has a lot of advantages, in my opiniton the amenity of the first one ist clear and so I would choose this one.

"C++ Algorithms, Boost and function currying" by Steve

Sat, 19 Jun 2010 05:38:35 -0500

The usage of iterators in the second version shows that the author of this post doesn’t understand the concepts of abstraction and of functional programming very well.

"C++ Algorithms, Boost and function currying" by Tim Smith

Tue, 15 Jun 2010 15:05:28 -0500

When Scott first wrote about why hand written loops are evil compared to the new style of doing things, he made three important points. Sadly, he made three huge mistakes.

1) He said it was easier to write correct code. He took a simple handle written loop that was incorrect and make multiple attempts at making a new style loop. Sadly, it would have taken one step to correct the hand written loop.

2) He said it was easier to write correct code (part 2). In his newly created “correct” routine, he incorrectly used as part of the code to select the proper template. Sadly, his input data was doubles. What would have been a trivial bug to catch in unit tests now becomes a more subtle bug to catch. (For example, inputs of 1,2,3 wouldn’t catch Steve’s bug, but 1.4,2.8,3.9 would have)

3) He said that the new fancy code ran just as fast. Sadly, it did not. Due to the complexity of the template code, the optimizer failed to place a temporary in a register thus resulting in the routine using stack space. The new fancy version ran THREE TIMES SLOWER than the hand written loop. (template optimizers have improved a lot since then)