Rhino Mocks 3.0 beta is out!

It seemed a long time coming, but finally
Rhino Mock's 3.0
is available, which of course also means

href="http://wiki.castleproject.org/index.php/DynamicProxy%20">Dynamic
Proxy 2 has made it to that sweet generic method support
nirvana as well :)



I don't know where I'd be without these tools, I haven't done a
.Net project without them in the last couple of years... in fact
it's fueled my reluctance over the last couple of years for
returning to bespoke development at any NZ dev shop which might
dictate other (crappier) alternatives ;o)



I also noticed that mono is getting it's C# 3.0 support slowly
sorted
... Extension methods are in, as is some Lambda
support... I need to sit down and spend some time thinking about
how I should go about unit testing some of this stuff, it's on my
list of "testing" things to do right after getting to grips with
RhinoMocks 3 and perhaps writing another blog entry on mocking
Base4 with all the new "goodies" - I need to do a monorail/base4
website for another little venture, so it's probably as good a time
as any.



Went for a swim at Omaha today... just can't get enough of the
beach this year - John
Campbell
turned up at the same time we did, there's only so
many "Not in front of John" jokes I can handle in one day... or a
life time ;o)

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Simplcity vs Ease of Injection...

Found myself writing a simple class for implanting "trial" logic for a client (as in you have 30 days left of your trial etc.) ... it relies on the current date and time, and so you can never really be assured your tests are robust unless you can control the current date & time within the test fixture (in fact any time you find yourself writing DateTime.Now alarm bells should be going off... even worse is logic based on DateTime.Now where it's evaluated more the once for a single function).

In the past I've generally Implemented something like an "IClock" interface, which would have a method like "DateTime GetCurrentTime()" or whatever seemed appropriate to the situation... but I decided to go with the lightweight solution of delegates instead in the morning, if only because I was being lazy I didn't see the need for creating an entire interface for such a trivial requirement... so we have:

private DateTime _trialExpirey;
private int _maxExecutions;
private TimeSpan _trialDuration;
private Func _nowFunction;

public TrialUpdater(DateTime trialExpirey, int maxExecutions, TimeSpan trialDuration)
: this(delegate { return DateTime.Now; }, trialExpirey, maxExecutions, trialDuration)
{
}

public TrialUpdater(Func nowFunction, DateTime trialExpirey, int maxExecutions, TimeSpan trialDuration)
{
if (nowFunction == null) throw new ArgumentNullException("nowFunction");

_nowFunction = nowFunction;
_trialExpirey = trialExpirey;
_maxExecutions = maxExecutions;
_trialDuration = trialDuration;
}

But I'm starting to wonder if this code doesn't smell a bit if I start using it other places... for instance:

  • Could I supply an alternative delegate via the castle container...?
  • Could I mock out the nowFunction parameter easily using something like RhinoMocks and still have it participate in constraints...?


I'm thinking in the case of mocking it out you would probably need to implement some interfaces which lines up with the generic delegates (Func and Proc etc.) - so I would end mocking out an IFuncEvaluator interface (or in this case IFuncEvaluator) -which would implement a method "T Evaluate();"... and the pass an anonymous delegate which in turn invokes the mocked IFuncEvaluator.

Though maybe I've missed something and mocking out delegates is doable with the current RhinoMocks..?

As for being able to inject a value for the nowFunction parameter, I'm thinking a nice solution would be to actually wire it up to a method on another service declaratively i.e.



    




Which I believe should be doable using a facility and a type converter... but I'm sure the devil's in the detail :)

At any rate, just a minor distraction, back to work.

As an aside the clocks a pretty boring example, but there are times
when you want to manipulate the time for instance:

  • If you want to manipulate the time (return dates as UTC instead of Local)
  • Clamp the current Time so it's limited to a certain level of accuracy... perhaps you have an external expectation that all dates will be recorded at a 10ms level of accuracy (perhaps you want to align database timestamps with timestamps within your application).
  • Perhaps your application uses the clock to work with snapshots of your domain model in the past.


How many people are actually using anonymous delegates and generic Func / Proc's in their day to day coding for tasks like this?
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LINQ fun - part two

Just a quick post, for part two let's look at grouping our results for display purposes... first off, I grab only the episodes which we think are "valid" (in this case ones which are assigned a series, episode and part number)...

EpisodeParser episodeParser = new EpisodeParser();

YouTubeSearcher searcher = new YouTubeSearcher(DeveloperId);

// get a list of all the parts we are interested in

IEnumerable parts = (from result in searcher.QueryByTags("QI", "Quite", "Interesting")
select episodeParser.Parse(result))
.Where(p => p.SeriesNumber > 0 && p.EpisodeNumber > 0 && p.PartNumber > 0)
.Distinct();

Obviously what I've done here is probably rather poor style, surely the where clause could have been inside the select statement??... but I'm just trying to illustrate how you can mix the two notations... next we're going to group the results up using some nested "group by" and object projections... this is disgustingly easy, what more can you say about it.

// group those parts

var allSeries = from part in parts
group part by part.SeriesNumber into series
orderby series.Key
select new { SeriesNumber = series.Key,
Episodes = from episodePart in series
group episodePart by episodePart.EpisodeNumber into episodes
orderby episodes.Key
select new {EpisodeNumber = episodes.Key,
Parts = from chunk in episodes
orderby chunk.PartNumber
select chunk
}
};

Great, I think that saved us a lot of time, compared to doing it ourselves in C# 2.0...  let's now generate a little page to view the results - for now I'm just writing code in NUnit fixtures - so we'll use Console.WriteLine... though in a website I would probably just use some quite similar brail template code.

foreach (var series in allSeries)
{
Console.WriteLine("

Series {0}

rn", series.SeriesNumber);
foreach (var episode in series.Episodes)
{
Console.WriteLine("

Episode {0}

rn", episode.EpisodeNumber);

foreach (var author in episode.Parts.GroupBy(p => p.Result.Author))
{
Console.WriteLine("

Author: {0}rn", author.Key);

foreach(var part in author)
{
YouTubeResult result = part.Result;
Console.WriteLine("part {1}  ", result.Url, part.PartNumber, result.ThumbUrl);
}
}
}
}

I've also dumped the output from this to an html page, if you'd like to have a look at it.

Next time I might have a look at storing the results of the youtube query with base4 and writing some code for a little daemon which can identify newly posted episode parts on a periodic basis... which should all lead towards implementing the RSS feed capability I discussed in  part one.

But for now I'm off to enjoy the sun!

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LINQ fun - part one

Well, the recent musings of Alex James have caught my interest around LINQ (part one and two) - and so I thought I would start having a play with LINQ and using it to query some well known web sites... and decided to go with dragging some info out of youtube...



Basically, I like QI (also known as Quite Interesting - british comedy show) - and there's a lot of episodes on youtube, querying on the tags "QI", "Quite" & "Interesting" returns about 1000 results... almost every result represents a part of an episode... and most people posting are kind enough to include something in the title or description of the video which lets you know which episode and series it belongs to...



However it's going to take some effort to actually start watching at series 1, episode 1 and work your way through the episodes in the right order by endlessly browsing youtube's search results... unless we start "value adding" - creating an "episodic" view over youtube's data.



At this point you could put your magic hat on and wish for features from you're youtube "episodes" site:

  • Perhaps an RSS feed notifying me of new episodes as they're listed on youtube daily.

  • A nice way to see a series, it's episodes, and each part that I need to play.
  • Maybe some aggregation of episode summaries from another web site for each episode (in this case I'm thinking maybe TVRage.Com...)

So you can quickly see that we can start making something virtually out of nothing, like MacGyver... but much lamer and without the hair.



First things first, I started having a look at YouTube's API - you can search by tags and get plenty of info back from their REST web service, but you can only get 20 results per page, 20 results isn't much cop so I built a simple class which gives access to the whole set of search results as an IEnumerableYouTubeResult> - here's the code for that:


public class YouTubeSearcher
{
private const string TagQuery = "http://www.youtube.com/api2_rest?method=youtube.videos.list_by_tag&dev_id={0}&tag={1}&page={2}";
private string _developerId;

public YouTubeSearcher(string developerId)
{
if (string.IsNullOrEmpty(developerId)) throw new ArgumentNullException("developerId");
_developerId = developerId;
}

public IEnumerable QueryByTags(params string[] tags)
{
if ((tags == null) || (tags.Length <= 0))="" throw="" new="" argumentnullexception("tags",="" "tags="" must="" contain="" one="" or="" more="">

for (int page=1; true; page++)
{
List results = QueryByTagAndPage(JoinTags(tags), page);
if (results.Count <= 0)="">
foreach (YouTubeResult result in results) yield return result;
}
}

private string JoinTags(string[] tags)
{
if (tags.Length == 1) return tags[0];

StringBuilder builder = new StringBuilder(tags[0]);

for (int i=1; i

return builder.ToString();
}

private List QueryByTagAndPage(string tag, int page)
{
Console.WriteLine("Querying by tag: {0}, page: {1}", tag, page);

Stopwatch watch = Stopwatch.StartNew();
try
{
List results = new List();

string uri = string.Format(TagQuery, _developerId, tag, page);
XPathDocument xpd = new XPathDocument(uri);

XPathNavigator xpn = xpd.CreateNavigator();

XPathNodeIterator xniError = xpn.Select(@"/ut_response");

xniError.MoveNext();

if (xniError.Current.GetAttribute("status", String.Empty) == "fail")
{
string expression = "/ut_response/error/description";
string errorText = xpn.SelectSingleNode(expression).InnerXml;

throw new YouTubeException("Error occured while querying youtube: {0}", errorText);
}

try
{
XPathNodeIterator xni =
xpn.Select(@"/ut_response/video_list/video");

while (xni.MoveNext())
{
XPathNavigator navigator = xni.Current;

string title = navigator.SelectSingleNode("title").InnerXml;
string url = navigator.SelectSingleNode("url").InnerXml;
string thumbUrl = navigator.SelectSingleNode("thumbnail_url").InnerXml;
string id = navigator.SelectSingleNode("id").InnerXml;
string description = navigator.SelectSingleNode("description").InnerXml;
int lengthInSeconds = int.Parse(navigator.SelectSingleNode("length_seconds").InnerXml);
string author = navigator.SelectSingleNode("author").InnerXml;

results.Add(new YouTubeResult(id, url, title, thumbUrl, lengthInSeconds, description, author));
}
}
catch (XPathException xpe)
{
throw new YouTubeException("Xpath exception occured: {0}", xpe.Message);
}

return results;
}
finally
{
Console.WriteLine("Query complete in {0}ms", watch.ElapsedMilliseconds);
}
}
}



Following on from that we need to parse each search result and attempt to pull out it's episode information:
  • Series Number

  • Episode Number
  • Part Number


At this point we might also make the assumption that parts should be grouped by the user who posted them - in case the same episode has been posted twice by two users (quite likely, people are silly).



Parsing part information could be done using successive LINQ queries, but It's actually not that pleasant considering we're generally interogating only two text fields - the title for the clip, and it's description - horses for courses - so instead I built a quick 'n dirty "EpisodeParser" class... here's the code for that:


public class EpisodeParser
{
private List _contributors = new List();

public EpisodeParser()
: this(
new SeriesContributor(),
new EpisodeContributor(),
new PartContributor(),
new XFormatContributor(),
new PilotContributor(),
new PartOfPartsContributor(),
new WordNumberPartsContributor())
{
}

public EpisodeParser(params AbstractContributor[] contributors)
{
if (contributors != null) _contributors.AddRange(contributors);
}

public EpisodePart Parse(YouTubeResult result)
{
EpisodePart ep = new EpisodePart(result);

foreach (AbstractContributor contributor in _contributors)
{
contributor.Contribute(ep);
}

return ep;

/*
* QI Series 4 EpisodePart 12 (part 3)
* s2e10 part 1/4
* Qi Series 1 Ep 5 Part 1/3
* QI 2x01
* Take Out 1
* QI Pilot EpisodePart part 6
* S2E09
*/
}

private class SeriesContributor : AbstractContributor
{
public override void Contribute(EpisodePart episodePart)
{
int? seriesNumber = ParseNameNumber(episodePart, "series", "s");
AssignSeriesNumber(episodePart, seriesNumber);
}
}

private class EpisodeContributor : AbstractContributor
{
public override void Contribute(EpisodePart episodePart)
{
int? episodeNumber = ParseNameNumber(episodePart, "episode", "ep", "e");
AssignEpisodeNumber(episodePart, episodeNumber);
}
}

private class PartContributor : AbstractContributor
{
public override void Contribute(EpisodePart episodePart)
{
int? partNumber = ParseNameNumber(episodePart, "part", "p");
AssignPartNumber(episodePart, partNumber);
}
}

private class PilotContributor : AbstractContributor
{
public override void Contribute(EpisodePart episodePart)
{
if (episodePart.Result.Title.ToUpper().Contains("PILOT"))
{
AssignSeriesNumber(episodePart, 1);
AssignEpisodeNumber(episodePart, 1);
}
}
}

private class XFormatContributor : AbstractContributor
{
public override void Contribute(EpisodePart episodePart)
{
int seriesNumber = 0;
int episodeNumber = 0;

if (SplitNumber(episodePart, ref seriesNumber, ref episodeNumber, 'X'))
{
AssignSeriesNumber(episodePart, seriesNumber);
AssignEpisodeNumber(episodePart, episodeNumber);
}
}
}

private class PartOfPartsContributor : AbstractContributor
{
public override void Contribute(EpisodePart episodePart)
{
int partOf = 0;
int parts = 0;

if (SplitNumber(episodePart, ref partOf, ref parts, '/'))
{
AssignPartNumber(episodePart, partOf);
}
}
}

private class WordNumberPartsContributor : AbstractContributor
{
private static readonly Dictionary _phrases;

static WordNumberPartsContributor()
{
_phrases = new Dictionary();
_phrases.Add("part one", 1);
_phrases.Add("part two", 1);
_phrases.Add("part three", 1);
_phrases.Add("part four", 1);
_phrases.Add("part five", 1);
_phrases.Add("part six", 1);
_phrases.Add("part seven", 1);
_phrases.Add("part eight", 1);
_phrases.Add("part nine", 1);
_phrases.Add("part ten", 1);
}

public override void Contribute(EpisodePart episodePart)
{
AssignPartNumber(episodePart, FindPhrase(episodePart, _phrases));
}
}
}



At this point we have the building blocks for starting to write some LINQ queries... here's my first test - running a basic "select all"...


YouTubeSearcher searcher = new YouTubeSearcher(DeveloperId);

IEnumerable results = from result
in searcher.QueryByTags("QI", "Quite", "Interesting")
select result;

Console.WriteLine("total results: {0}", results.Count());



Trying a more explicit style of query, and parsing episodes:


EpisodeParser episodeParser = new EpisodeParser();

YouTubeSearcher searcher = new YouTubeSearcher(DeveloperId);

IEnumerable parts = searcher.QueryByTags("QI", "Quite", "Interesting")
.Select(result => episodeParser.Parse(result))
.Where(part => part.SeriesNumber == 1 && part.PartNumber == 1)
.OrderBy(part => part.EpisodeNumber);

foreach (EpisodePart part in parts.Distinct())
{
Console.WriteLine(part);
}



Which will let us know which episodes in series 1 exist...



Bit of a rush, but next time I'll start digging in a little deeper...



At this point though it's worth noting that we have some stuff for free because of IEnumerableT>...
  • Search results are being processed as their yielded, if we're just looking for the first matching item for a query we can stop without having to request additional result pages on a match is made.

  • Same goes for episodes, we only parse them as they are required - no unnecessary overhead.


So far nothing has required LINQ, but I think we'll start to see it being a great time saver come the next couple of parts... compared to writing the code ourselves.



We shall see!
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PHP...

Background



As a bit of background, for the last couple of months I've been doing some work for a personal client aside from the work for
Seismic Technologies which is on the back burner till we pick up some more investment interest (I'm still the lead dev though) - the project is an add-in for an existing product (COM interop) which be must be deeply-integrated, as well as being capable of being used in stand alone mode...



It's a very advantageous project considering the time frame, but that's part of the fun :) Once the clients moved forward on some marketing I'll post a little more about some of the challenges I've faced along the way.



At any rate - the project's stalled briefly while the clients doing a little business analysis to get the underlying methodology sorted - so they've asked me to switch across to building the license generation / customer portal / license purchasing module for their preexisting CMS system (CMS made simple - PHP) ... where are the ruby or Monorail CMS's to wean my clients onto?

PHP... ack

... So I haven't used PHP in anger for years and years, but the one advantage of dynamic languages is you can generally hit the ground running a lot quicker then their statically compiled competitors...  maybe PHP even more so because it's focused on web development.



So far the two things that have bugged/puzzled me are:
  • Classes don't call their base classes default constructor implicity - you have to do that yourself.  This isn't all bad, at least you can control when the default constructor is called.

  • Methods are instance, static and pseudo-instance all in one...


I think the second one bugs me more because you end up with 2+ potential code paths that should be accounted for in testing, if your exposing an "api" for consumption - or more importantly you should throw an exception for the usages you don't wish to allow (I'm probably missing the "quick and dirty" point here of course ;o) - it's hard to fight years of  instance methods != static methods...



Maybe I'm just old fashioned and there's nothing wrong with this, I should have a flick through Programming Language Pragmatics again, there must be some other dynamic languages with similar behavior?



At any rate, the example:


class A
{
function foo()
{
if (isset($this)) {
echo '$this is defined (';
echo get_class($this);
echo ")n";
} else {
echo "$this is not defined.n";
}
}
}

class B
{
function bar()
{
A::foo();
}
}

$a = new A();
$a->foo();
A::foo();
$b = new B();
$b->bar();
B::bar();



And the output of that little example is shown below, notice how A:foo() knew it was being called from class
B
...  I wonder what phalanger is doing under the hood to achieve the same thing in the CLR...


$this is defined (a)
$this is not defined.
$this is defined (b)
$this is not defined.

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