Tag Archives: Patterns

Module Binder Pattern proposal

Whoa! This has been quite an event, the Directions EMEA 2016 in Prague. There has never been this many people (1.700+) and it was quite a pleasure connecting again with old friends, and meeting new friends. Also, it has been quite a pleasure listening to many good sessions, and an even bigger pleasure delivering four of them.

And this is why I am blogging now – to follow up on my promise during my Polymorphic Event Patterns for C/AL. I promised you that I’d post my pattern proposal online, and here I am doing it.

Let’s get started.

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Gentlemen’s agreement pattern, or handling the “Handled” pattern

I’ve delved deep into design patterns story with my last two blog posts, but I am far from over. The patterns I discussed are the ones we could use up until NAV 2015 (we can still use them, of course!) but some more robust loose coupling (excuse the near-oxymoron) can be achieved with what NAV 2016 brought along: events.

It’s the “Handled” pattern. This pattern comes from Thomas Hejlsberg, a chief architect and CTO of Microsoft Dynamics NAV, and was first described by Mark Brummel on his blog. It’s a powerful loose-coupling pattern that successfully addresses the shortcomings of all design patterns I discussed earlier. I would prefer calling this pattern Event Façade rather than “Handled”, but it’s not my baby to christen.

Let’s take a look.

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TempBlob Façade: a pattern proposition

Achieving some kind of polymorphism in C/AL has always been a problem. The fact that true polymorphism with pure C/AL is outright impossible has not stopped the more stubborn of us to at least give it a try. That’s how some cool patterns emerged.

The façade pattern has been evangelized by Gary Winter so eagerly that he couldn’t find time to formally describe it. The other pattern that comes close is the variant façade pattern. It was formally described at the patterns Wiki page, but – to the best of my knowledge – was first figured out by Arend-Jan Kauffmann.

These two patterns can go a long way. No, they are not coming anywhere near true polymorphism, but will achieve some cool loose binding when you need it.

In my practice, I took a step further, and I think it’s about time I share it. Let’s see if it works for you as well as it did for me.

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OnAfter table event subscriber patterns and antipatterns

The purpose of events is to simplify business logic customization while not impeding upgradeability and general extensibility. However, there is one particular class of events that may cause troubles: OnAfter* table events. There are four of them: OnAfterInsert, OnAfterModify, OnAfterDelete, and OnAfterRename.

If you need them, you must be careful.

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.NET Tips & Tricks: Mediator Pattern (on steroids)

When I was writing my last post I had a distinct feeling that I was trampling over some boundaries of good NAV design. After all, you should not do stuff like that, NAV isn’t meant to do things like that, or at least that was how I felt.

And then two things happened.

First, I asked myself: what the heck, why not? What exactly is NAV meant to do, and why not things like that? If folks at Vedbæk didn’t provide an out-of-the-box solution for the problem, why should the problem stay unsolved?

Second, my dear friend and a fellow MVP, Hrvoje of Hudo’s Vibe, identified the thing as the mediator pattern. So, the thing I’ve done to NAV, civilized world has been doing to their programming environments for a long time.

And then I decided to take it all to a different level altogether, and expand the simple class which didn’t do much but raise events on itself when its method was called, into a full-scale framework. And here it is, the mediator pattern incarnated into a brand new Dispatcher class, adapted to NAV, and with features that make it truly flexible. I do not dare starting to think what are all the situations where you could put this thing to use in NAV.

Read on.

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