Posts Tagged c++

Chimera wishlist : !NullReferenceException

July 18, 2011 at 12:00 pm · Filed under c++, code, development, programming ·Tagged , , , , , , , , , , , ,

What features from other languages do you wish your main development language had?

As someone whose first real applications were written in C++, the thing that always bugged me about C# and Java (after they got generics and autoboxing sorted) was the way they handled references. In my C++ mind, C# and Java pass pointers around, and pointers are allowed to be null. So every single time I have to use them, I have to check them for null, or set up the caller to make sure they’re not null. As Anders Hejlsberg points out, that single fact causes more problems than anything else in C#.

Also, I wish C# allowed const references like C++ to guarantee an object isn’t modified within a method when passing by reference, which is always useful to avoid copying large objects. C# would have to support const methods too, of course.

50% of the bugs that people run into today, coding with C# in our platform, and the same is true of Java for that matter, are probably null reference exceptions. If we had had a stronger type system that would allow you to say that ‘this parameter may never be null, and you compiler please check that at every call, by doing static analysis of the code’. Then we could have stamped out classes of bugs.

But peppering that on after the fact once you’ve built a whole platform where this isn’t built in… it’s very hard to pepper on afterwards. Because if you start strengthening your APIs and saying that you can’t pass null here or null here or null here, then all of a sudden you’re starting to break a bunch of code. It may not be possible for the compiler to track it all properly.

Anyway, those are just things that are tough later. You sort of end up going, well ok, if we ever get another chance in umpteen years to build a new platform, we’ll definitely get this one right. Of course then we’ll go and make other mistakes! But we won’t make that one.

http://www.computerworld.com.au/index.php/id;1149786074;pp;3

So, what do you wish for?

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Adding HTTP Headers to WaTiN tests

August 17, 2010 at 4:10 pm · Filed under code, development, krugle, programming ·Tagged , , , , , , , ,

EDIT (2010-08-17 21:26 GMT) : I found a bug in the COM interop that prevented the code from compiling on certain machines. This has now been fixed so if you copied this code before, please try it again.

It’s taken me a while to figure this one out, so I’m putting up a post in case anyone else has a problem. In our system, we need to inject specific headers into each request to simulate our live environment, which means either injecting those expected headers into our tests or having different controller behaviour for dev and live environments.

WaTiN is great for all the other tests we do, but it doesn’t currently support adding HTTP headers to a request, and after a look through the source code, I can see the hoops they’d have to jump through to make it cross-browser. For our purposes, we just needed IE support, so we have the option of intercepting the events on the IE instance directly.

MyHeaders is a property of type object for COM interoperability. It uses the SHDocVw dll to interact with IE. If you allow MyHeaders to be null, you will get an infinite loop and a StackOverflow. I will not guarantee anything about this code, but I hope it’s one small step towards native WaTiN cross-browser HTTP headers support. I am happy to hear about any success you have using or extending this. I will leave setting of test-specific values and compatibility for other browsers as an exercise for the reader.

Snippet

        private object MyHeaders { get; set; }

        private void beforenavigate2replaceheaders(object pDisp, ref object URL, ref object Flags, ref object TargetFrameName, ref object PostData, ref object Headers, ref bool Cancel)
        {
            if (Headers == null)
            {
                Cancel = true;
                object objTestHeaders = MyHeaders;
                _ieInstance.Navigate2(ref URL, ref Flags, ref TargetFrameName, ref PostData, ref objTestHeaders);
            }
        }
 
        private void beforenavigatereplaceheaders(string URL, int Flags, string TargetFrameName, ref object PostData, string Headers, ref bool Cancel)
        {
            if (Headers == null)
            {
                Cancel = true;
                object objFlags = Flags;
                object objTargetFrameName = TargetFrameName;
                object objTestHeaders = MyHeaders;
                _ieInstance.Navigate(URL, ref objFlags, ref objTargetFrameName, ref PostData, ref objTestHeaders);
            }
        }

        private void SetUpBrowser()
        {
            CloseBrowser();
            Settings.AutoMoveMousePointerToTopLeft = false;
            Settings.MakeNewIeInstanceVisible = true;
            Settings.WaitForCompleteTimeOut = 120;

            _ieInstance = new SHDocVw.InternetExplorerClass();
            MyHeaders = "Content-Type: application/json\r\n";
            ((SHDocVw.InternetExplorerClass)_ieInstance).BeforeNavigate += beforenavigatereplaceheaders;
            ((SHDocVw.InternetExplorerClass)_ieInstance).BeforeNavigate2 += beforenavigate2replaceheaders;
            _browser = new IE(_ieInstance) { AutoClose = true });
        }

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July Tech Meetup Glasgow: The Beauty of Code – Techmeetup

July 29, 2009 at 2:03 pm · Filed under code, programming ·Tagged , , , , , , ,

The video for my Genetic Algorithm talk has been posted to the TechMeetup blog for those who want to watch it (and can withstand my stuttering ;-) ). If you want to grab the original presentation itself, it’s in the repository for the C++ template project: geneticalgorithmtemplates \ talks and presentations \ techmeetup glasgow 20090701

Craig Nicol on Genetic Algorithms

Craig provided a high-level introduction to what genetic algorithms are and how they can be used.Genetic algorithms is a search technique used in computing to find exact or approximate solutions to optimization and search problems. As the name suggests, they’re inspired by the process of evolution in the natural world. The typical genetic algorithm consists of a genetic representation of the solution domain, and a fitness function for evaluating the solution domain.Craig used example to clarify the topic and his presentation stimulated an interesting discussion of potential applications of the technology.

July Tech Meetup Glasgow: The Beauty of Code – Techmeetup

Craig Nicol talks about Genetic Algorithms from TechMeetup on Vimeo.

Hope to see you at the techmeetup talk tonight.

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Genetic Algorithm Templates

June 29, 2009 at 11:24 pm · Filed under code, programming ·Tagged , , , , , , ,

I had a great time at the Tech MeetUp (@techmeetup) in Glasgow this week. If you want to meet up with other tech minded folk in Scotland, it’s definitely worth checking out. See the details at the end of this post.

At the meeting this week, I got talking to a few folk (including John Gallagher who gave a great talk) about AI and Genetic Algorithms. This inspired me to dig out my old experimental code for doing GAs using C++ Templates. The code’s very rough and ready, and it was written long before I discovered TDD or subversion, but it should be standards-compliant, and it compiles in the latest GCC (I can’t vouch for other compilers, if you try it, let me know). As it’s a source-code library, you’ll have to compile it yourself, but if you don’t know how to use a compiler, you’re probably reading the wrong blog anyway. I will be tidying up the code and creating a wish list as I get the chance, but I’m throwing it out there in case it’s useful to anyone.

If you’re interested, check it out at the link below and let me know what you think.

Genetic Algorithm Templates

If you’re interested in Tech MeetUp, you can see videos from previous talks at their website

The Tech MeetUp is the informal opportunity to meet other developers and tech companies, to showcase your hacks or projects, and to find out what’s happening around us. Help build the tech community – set up a profile and come along to a Tech MeetUp.

Home – Techmeetup

You can find out about upcoming meetings on their mailing list

Description: An easily accessible and friendly community of tech minds, skills and startups around Scotland and Northern UK.


Tech Meetup | Google Groups

Blogged with the Flock Browser

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Genetic Algorithm Templates

June 5, 2009 at 2:09 pm · Filed under code, programming, search ·Tagged , , , , , ,

I had a great time at the Tech MeetUp (@techmeetup) in Glasgow this week. If you want to meet up with other tech minded folk in Scotland, it’s definitely worth checking out. See the details at the end of this post.

At the meeting this week, I got talking to a few folk (including John Gallagher who gave a great talk) about AI and Genetic Algorithms. This inspired me to dig out my old experimental code for doing GAs using C++ Templates. The code’s very rough and ready, and it was written long before I discovered TDD or subversion, but it should be standards-compliant, and it compiles in the latest GCC (I can’t vouch for other compilers, if you try it, let me know). As it’s a source-code library, you’ll have to compile it yourself, but if you don’t know how to use a compiler, you’re probably reading the wrong blog anyway. I will be tidying up the code and creating a wish list as I get the chance, but I’m throwing it out there in case it’s useful to anyone.

If you’re interested, check it out at the link below and let me know what you think.

Genetic Algorithm Templates

If you’re interested in Tech MeetUp, you can see videos from previous talks at their website

The Tech MeetUp is the informal opportunity to meet other developers and tech companies, to showcase your hacks or projects, and to find out what’s happening around us. Help build the tech community – set up a profile and come along to a Tech MeetUp.

Home – Techmeetup

You can find out about upcoming meetings on their mailing list

Description: An easily accessible and friendly community of tech minds, skills and startups around Scotland and Northern UK.


Tech Meetup | Google Groups

Blogged with the Flock Browser

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