Thursday, October 31, 2019

How long does it take to develop a "complete" MVVM framework for Delphi?

This is a really good question. (Btw. what is complete? We all know a framework is never complete)

Maybe you have a different question in mind... Is it worth to spend x man days trying to develop it? 

Spoiler - Yes!

If I had not believed that it was possible, I would never have started another attempt. 

If you have not read my other posts about MVVM - yes I've been trying this since 2015. (Of course not all the time).

Is this my last attempt? - I hope so - or better, I hope that this is the final version that fulfills all my wishes - as well as yours  (one of which is to prove: Yes, with delphi it is possible to develop a framework with the idea behind MVVM)  

Most the time I had to spend on a better binding structure, studying the source of this unit... Oh boy, I have to refactor this code for better readability.

We all know the MVVM images with the three colored boxes and  the fancy arrows labeled with read, write, binding, propertychange, event or whatever. Everybody starts with this.

Then you google for tutorials or search at youtube. Yes, you will find some stuff, but if you dig deeper and depper into MVVM you have to rethink about these videos. So many mistakes. (of course from my point of view).

On the surface, the MVVM-Pattern is just a guide how to separate the visual parts from logic and put everything in a state to be able to perform unit tests. Is this so? 

Yes, but the devil is in the detail.

And everybody is doing it a little bit different. Then you learn from this tutorials how to do "a" and by reading more and more "a" is suddenly an antipattern and everybody is blogging about "a" is bad you have to do it like "b". Sometimes it sound like the discussions about using FreeAndNIL. (Please no comments on this topic) ;-)

Who holds the instance of a, who can create b and how to perform c? Using the approach from a tutorial or is there better way? - is the better way still the "right" way? - and who decides this? Some experts or MS? What is an expert in MVVM? 

If you are in front of your screen staring at an empty unit in the IDE - I call this 

"The loneliness of development" 

you easily get overwhelmed from all the decisions you have to make. #AloneInTheDark Only if you are using the darkstyle!

My advice - talk to an other developer. Perhaps she/he is not right or has a complete different idea or opinion - that does not matter. Take the feedback and do it your way, perhaps you can adjust your first idea with the feedback.  

And here I am - 3 month into the final version. (only in my spare time I do the MVVM development). It's working - and it is fast - and it is easy to use - and there is (nearly) no code in the View/Form - and most of the necessary (stock) visual controls are already working (no imposer necessary) - and you have to write less code you would expect - and I love the implementation. 

More than half the time is debugging time (so far). I did not use TDD this time, because I had no idea where to start with the tests. 

Good news:
- The implementation is working with FMX ( this was no question, wasn't it ) but also with VCL.
- I have a small team of developers for beta-testing.
- There will be two different versions. Of course as a Plugin to my FDK, but also a stand-alone Version.

The FMX Version is more advanced at this state and the VCL version will see "the light of release" a little bit later. The documentation is not existing at the moment and to show the benefits of the framework I have to do some youtube-videos - this is for sure. But not this year - perhaps you will see "something" at CodeRage 2019. (Nov 11. 2019). But this is not decided today.

To answer the question of the blogpost: 6 Month or 4 to get a beta and perhaps one more month for documentation and another one for videos. I will use the FDK installer, that is capable of doing the user registration, updates, online-store and invoices. (bug tracker is coming) Two month. So overall until everything is out including VCL - The final answer is one year.

I assume, that with the final framework, I will be able to create MVVM based Apps at least in half the time then before, just a little bit more than doing good old RAD-stuff, but everything testable. By combining this framework with my FDK you can build a multi-platform-app in weeks instead of month. 

The future of App-development will be great.

PS.: The new Version of the installer is using gnostice document studio for FMX. At forentage I told everybody that I not using this component by myself - this has changed. Thanx to my friend Girish Patil for the support.


No comments:

Post a Comment