Coding in Istanbul 1: PHP in Turkey

I’m having a çoban kavurma in a restaurant with my old mate Jeff who lives in Istanbul. We stopped for lunch in one of the busy pedestrian streets of Kadiköy on the Asian side of the city.

We spent most of yesterday coding on Jeff’s doctors appointment website. We added a small admin functionality that will save him time when mailing doctors. He’s currently working on getting more doctors registered: it involves finding their details and emailing them one by one. Obviously spamming them all in one go is out of the question so each email is slightly personalised (quoting the doctor’s own website). Yet they all follow the same template so there is some room for automation.

Jeff also needs to track how doctors open and view the campaign emails. Each email contains a number of links: to the appointment’s website, press articles, facebook and to twitter. Pretty clever: each link calls a php on his website that logs the doctor’s identifier along with the identifier of the link. Then he can run a report that shows various stats about who clicked what link…

Good places to take the netbooks out in Turkey include a growing number of restaurants, Starbucks, Gloria Jeans… and Wifi is almost always free!

Gloria Jeans is a great place to sit down with the laptop: more comfortable than Starbucks and less crowded. The one in Ortaköy is perfect: beautiful view to the Bosphorus, 3 levels, smoothies, cheesecakes, tosts (paninis) and free wifi.

View Istanbul in a larger map

Setup, TearDown, When to Mock?

 

I’m writing this while eating at the Launceston Place, a very comfy restaurant near Gloucester Road. Warm decor, soft lighting and excellent service.

• Setup and TearDown

Only use those to respectively initialise then destroy mock objects. Methods with [Setup] and [TearDown] attributes are called before and after each test so they’re the only methods that guaranty that things get cleaned up.

Best to avoid the [SetupFixture] attribute (to mark a class that contains Setup and Teardown methods called just once before ALL tests), as well as [TestFixtureSetup]/[TestFixtureTeardown] (called once only before all tests in a fixture). I tried to be clever and used them and ended up having to debug nasty side effects. Unit tests are supposed to run in isolation, so just one [Setup] before and one [TearDown] after each of them, that’s it.

• What should be mocked?

Yesterday while writing a UT I bumped into this question: should I bother writing a mock for that object or can’t I just use the real thing?

One answer: objects that access external systems (DB, hard-drive, client API to some server-based system, …) should always be mocked (for unit-tests that is, not integration tests), otherwise the test is not repeatable, and it’s slow…

If a method under test accesses an injected object and this object does only in-memory stuff, then no need to mock it. It would make sense to mock it because after all this injected object is not actually the thing you want to test… Still, the more real objects are covered by the test, the better. As long as they all run in-memory and do not prevent the test from being repeatable, all is well. So no need to waste time writing a mock in that case.

Got to Treat Yourself

I bought myself a Christmas present. Next week I’ll receive this neat little thing:

It’s a VAIO X-Series.

This is a replacement for the VGN-SZ5 that I carried around every day in a rucksack for more than two years. Now the rucksack will disappear to be replaced by a tiny messenger bag.

Premium carbon finish, SSD drive, embedded 3G. Extremely thin and less than 900g. This is going to be pure pleasure.

In 2007 netbooks were not around yet and I needed something to write code on the go, not just in my lounge. I got the VGN-SZ5 and a Wenger SwissGear rucksack, both of which I’m still using today. I went everywhere with them: Hertfordshire, TechEd Barcelona, Egypt, the French Pyrenees (picture), Paris, Istanbul… In London I use the Vaio in the tube, in Starbucks, Costa, in pubs, in restaurants (which is extremely annoying to people I go out with).

Last year the rucksack felt a bit heavy on my shoulders so I started looking around for a netbook. I read reviews and benchmarks in magasines, tried out all sorts of models in the shop… Samsung, Asus Eee, Acer, Lenovo, MSI Wind… It wasn’t quite that. Either the 3G card was not embedded, or the thing was too bulky… Not sexy enough.

The first time I saw the X-Series in a Sony shop (in October last year two days before the official UK launch), I immediately thought “I want that”. I gave myself some time to think it over (it’s a bit of an investment). In its October 2009 review, PC Pro said:

But the real problem for the X-Series is its price. (…) Who, though, can lavish £1,130 exc VAT on a vanity laptop such as this?

I just ordered one.

 

Cheap IoC in native C++

In a 2008 episode of dnrTV James Kovac describes how to create a very simple IoC container. All the container does is mapping the name of an interface to an instance of this interface.

Easy to do in .NET with a generic Dictionary, but what about native C++? It turns out it's not that much more difficult: all you need is a STL map and C++'s typeid. 

What is an IoC container?
A class that given an interface ISomething returns the concrete object implementing ISomething.


Why do you need an IoC container ?

It's one way to do dependency injection.

Let's say you want to unit-test some business layer that relies on a data layer. The business layer sees the data layer through an interface (let's call it IDataLayer). The actual instance of IDataLayer is created by either:

• the entry point of the code that uses the business layer (an executable for instance). This is production code and it has to create the object connecting to the real database.

 

int _tmain(int argc, _TCHAR* argv[])
{
    // Create the concrete DataLayer object
    DataLayer dataLayer;

    // Register it with the resolver
    Resolver::Register<IDataLayer>(dataLayer);

    BusinessStuff businessStuff;
    businessStuff.DoStuff();

    return 0;
}

• the unit-test code. The IDataLayer object in that case is a fake object that doesn't connect to the real database and therefore makes unit-tests easily reproducible and fast.

void BusinessStuffTest::DoStuff_Nominal_DoesNotRaiseException()
{
    // Arrange

    // Create the concrete DataLayer object
    FakeDataLayer dataLayer;

    // Register it with the resolver
    Resolver::Register<IDataLayer>(dataLayer);

    BusinessStuff businessStuff;

    // Act
    businessStuff.DoStuff();

    // Assert
    dataLayer.AssertStuffWasDone();

}

Implementation of the Resolver class
The Resolver class has two methods Register and Resolve. Here is the code for the Resolver class (very straightforward):

#pragma once

#include
#include

using namespace std;

///
/// Allows you to Register and Resolve global objects
///
class Resolver
{
    static map<string, void* > typeInstanceMap;

public:

    template<class T> static void Register(const T& object)
    {
        typeInstanceMap[typeid(T).name()] = (void*)&object;
    }

    template<class T> static T& Resolve()
    {
        return *((T*)typeInstanceMap[typeid(T).name()]);
    }
};

This is a just a starting point. In production Resolver could do with methods such as Unregister(), IsRegistered(), UnregisterAll()...


An IoC container is one way to do dependency injection. Other ways include:

• pass the injected object using the constructor
• pass the injected object using a setter method

Both methods above can become tedious very quickly in a big project.
I tried all 3 methods and I find the IoC approach scales rather well. I've used it for 10 months in a production project and it works nicely with unit tests.

Resources:

Jean-Paul Boodhoo on the gateway pattern
Roll your own IoC container (dnrTV)
The Art of Unit-Testing where Roy Osherove tells everything about dependency injection and fake objects.