Archive for the 'Blablabla' category

I think I understand bounded contexts

published on October 24, 2017.

Earlier this year I started reading the DDD book by Eric Evans. Together with the Eventsourcery videos from Shawn McCool, the first three chapters of the book were… easy to understand, even. Lots of “A-ha!” and “Oh!” moments, followed by “That makes perfect sense.” statements, and a couple of excited “I knew that!”-ones. Then I got to the chapter with the bounded contexts. I read the first few pages, thought about them… Then read them again, and thought some more. Then I put the book back on the shelf for a few months.

Last night I read it again, and then…

Click!

A bounded context is a point of view.

A bounded context defines how a section of a business sees, thinks, talks about a subject that is important to that section of the business. And we represent that business subject with a model. That same business subject can be present in different sections of a business, but every section views it differently. To some extent, at least. That is the reason why the context of a model is important — we need to know how to model a subject for that specific business section.

And we need to put boundaries on those models — we must prevent the mixing of, what might seem same, models between these contexts.

A book is a book, right?

Depends on who you ask.

If you ask a publisher, a book has a title, a writer, a cost, a price, and a category. If you ask a seller, a book has a title, a writer, a cost, a price, and a category. They talk about the same things, right?

For a publisher a book has a working title, and a published title. For a seller a book has a title. For a publisher a book has a writer, who needs to be payed. For a seller a book has a writer, which is just a name on the front cover of the book. For a publisher the cost of a book includes the cost of the writer, the editor, the designer, the printing, the binding. For a seller the cost of a book includes the buying price, maybe some discounts from the publisher on the quantity purchased, the paychecks of the store clerks, bills for running the store, taxes… For a publisher the price includes the producing cost plus the profit they want to make. For a seller the price includes the buying cost plus the profit they want to make, and maybe some discounts they want to give to buyers. For a publisher the category can be fiction and non-fiction books. For a seller the category can be epic fantasy, sci-fi, horror, thriller, programming, design, recipe books…

See where am I going with this?

Depending on the point of view, depending on the context, the same book can mean two different things for two different business sections in the business of selling books. Even if at first we might think there is no difference, once we start talking to the business people, these differences will pop-up.

We should also respect the boundaries between these two contexts, so that we always know about what cost or what price we are talking about. Otherwise, the seller would quickly run out of business if they’d sell books at the publisher’s price.

This is just a model

Of course, there is more to bounded contexts, models, DDD, etc., than what I wrote here. More to read, more to learn, more to think, more to write.

Happy hackin’!

Bug triage, the paperwork of open source

published on May 24, 2017.

Everyone loves contributing patches to open source projects, adding new features. Some even like to write documentation.

Probably the least talked about way of contributing to open source is triaging issues (I have no data to back this statement, so I might be wrong!).

I do believe however that it can be the biggest help to project maintainers, because with issue triage out of the way, they are left dealing with the “bigger” problems of the project, such as fixing difficult bugs and implementing new features.

Ideally, a good issue report will include the version numbers of the affected projects, a good description of what the user tried to do, what did they experience, expected and actual results, any logs or stacktraces, and even the smallest possible test case that reproduces the issue being reported.

I say ideally, but that’s not always the case. Sometimes the report has a lot less details, does not include version numbers, or any other information that would help identifying the underlying cause of the issue. In those cases someone needs to go through the reported issues and ask for more information.

It’s paperwork

Issue triage boils down to going through the list of open issues for a project and making sure that the reports include as much as possible useful information. If the reporter hasn’t provided everything needed, we should ask them for more details.

If the initial report includes just enough information to start investigating, we could that as well. Start digging into the codebase and try to figure out what’s going on. If the project has automated tests, we can use them to get a better picture of the issue, and maybe even provide a failing test case to the maintainers. Fun fact: this is how I started with unit tests and test driven development - by submitting failing test cases to projects.

When we deem that we have enough information, we can try to reproduce the issue, and confirm or deny its validity.

Some issues are not really issues, but a case of misconfigured library, or documentation not being read fully. In those cases the solution is not to leave a “RTFM” comment and close it. Asking if they read pages X or Y, is a much better approach. It might be that the documentation is not detailed or clear enough, so we need to update our docs.

Sometimes it’s the lack of documentation that is the real issue.

Once we have enough information, we can leave a comment for the maintainers saying that we managed, or not, to reproduce the bug. From there the maintainers can take over and deal with the issue as they see fit. Or we could attempt at writing a patch and fixing it.

Bug? Feature? Support?

Users will open all kinds of reports. There will be issue reports, there will be feature requests, and there will be questions asking for support.

Deciding on which is which is also a part of issue triage. Label them accordingly, so maintainers and contributors will have an easier time filtering them out.

If you are familiar with how the software works, you might provide an answer to a question and help the user, again taking of the load from the maintainers.

No experience required

One of the best things for me about issue triage is that we don’t need to have experience with the project, let alone be experts in using it. Most of this is communicating with others, asking for more feedback, and making sure that the persons who can decide on the reports can do so with least effort required. Of course, having experience does help, but that’s the way with everything in life, I guess.

Besides, this is also a great opportunity to learn more about the project and the ecosystem around it.

While the work is not grandiose, it will help in getting better at communication skills, it will help the project to move forward just a little bit faster, and it is a great way to contribute to open source projects.

Happy hackin’!

P.S.: Sometimes if you wait long enough, the reporter won’t even remember what the issues was, and they’ll just close the issue.

Everybody knows that

published on May 08, 2017.
Heads-up! You're reading an old post and the information in it is quite probably outdated.

Back in December last year, Matthew Turland published a blog post asking “Why aren’t you speaking?

It made me think.

What I realised is that I always havehad this feeling that everybody already knows what I know.

Is that part of an impostor syndrome?

I don’t know. I really don’t feel like an impostor. I know what I know, I’m perfectly fine accepting that I don’t know everything… but then there’s this feeling that everybody else knows what I know. It’s a strange feeling, I’m not even sure if I can explain it properly.

This also led me to realise why I don’t blog more often. I like blogging. I like writing. I don’t consider myself being a good writer, but with English being my third language, mostly self-taught, I think I do quite alright.

It’s the same thing as with me not speaking at a conference or a user group — everybody knows that.

After doing some more thinking on this subject, there’s only one logical result — it is not possible for everyone to know what I already know. It’s just not possible.

I have learned, and still am learning from other people, by either reading their blogs, or hearing them talk, or looking at their answers on StackOverflow, or digging through their code on GitHub… Surely there are others out there that can learn a thing or two from me.

I also “agreed” with myself that not every blog post needs to be an essay, that it’s OK to publish a couple of short paragraphs, quickly writing down the things going around in my mind.

With those thoughts, with that kind of a mindset, I set out to start blogging again. Since December, since Matthew’s post, I blogged 20 times. I don’t think I have written so many posts in the past 4 years.

Oh, and I gave a talk at two different occasions as well.

Thanks Matthew.

Tags: about, blogging, blog.
Categories: Blablabla.

Recording screencasts of OSS contributions

published on April 19, 2017.
Heads-up! You're reading an old post and the information in it is quite probably outdated.

I enjoy contributing to open source projects, and I learn a lot while doing it. When someone asks me for advice on how to improve as a programmer, I usually tell them to find an open source project that interests them, and start contributing.

Easier said than done.

I’ve been contributing since… early 2009 I think, when I joined the Zend Framework mailing list.

To try and bring closer contributing to beginners, I decided to start recording screencasts of me doing open source contributions. To give a glimpse of how I do it.

So far I have created 4 of them and uploaded on YouTube. The quality is not perfect, but I think it’s good enough. There’s no video editing, I want to show how I really do it, no fixing of mistakes, no retakes. I use zoom to start a “meeting” and then share and record the screen. It’s actually the best screencasting software for Fedora I’ve found, and it’s not even a screencasting software ¯\(ツ)/¯

While doing these screencasts I also realised that I quite enjoy doing this and the whole process has the added bonus of me actual doing rubber ducking, because, well, I talk all the time as I do things.

Also, potential clients and employers can get a peak at how I work.

Happy hackin’!

Waste an hour on a stupid mistake

published on April 07, 2017.
Heads-up! You're reading an old post and the information in it is quite probably outdated.

I made such a stupid mistake today and lost an hour of my time trying to figure out what the hell is wrong, that I just have to blog it.

I was working on embedding a Symfony form into another form, following the documentation to the letter… Yet there I was staring at this stupid error message:

The options "0", "1" do not exist. Defined options are: "action", "allow_add", "allow_delete",
"allow_extra_fields", "attr", "auto_initialize", "block_name", "by_reference", "compound",
"constraints", "csrf_field_name", "csrf_message", "csrf_protection", "csrf_token_id",
"csrf_token_manager", "data", "data_class", "delete_empty", "disabled", "empty_data",
"entry_options", "entry_type", "error_bubbling", "error_mapping", "extra_fields_message",
"help", "inherit_data", "invalid_message", "invalid_message_parameters", "label", "label_attr",
"label_format", "mapped", "method", "post_max_size_message", "property_path", "prototype",
"prototype_data", "prototype_name", "required", "translation_domain", "trim",
"upload_max_size_message", "validation_groups".

What the hell…

Excerpt of the code that was throwing the error:

<?php
declare(strict_types=1);

namespace AppBundle\Form;

use AppBundle\Form\SampleType;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\Extension\Core\Type\CollectionType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolver;

class MultiSampleType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('samples', CollectionType::class, [
                'entry_type', SampleType::class,
                'allow_add' => true,
            ]);
    }

    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults(array(
            'data_class' => null,
        ));
    }
}

I read the documentation over and over again, searched for any one else coming up with the same error, went through the issues on the Symfony repositories… Nothing.

Now when I look at this code sample the error is poking my eyes out, but this morning when I was looking for it… Crickets.

Let’s “zoom” in:

<?php
->add('samples', CollectionType::class, [
    'entry_type', SampleType::class,
    'allow_add' => true,
]);

Do you see it?

The error is that the entry_type should be a key, instead of a value, and SampleType::class is the value for the entry_type key.

<?php
->add('samples', CollectionType::class, [
    'entry_type' => SampleType::class,
    'allow_add' => true,
]);

So stupid.

Oh well, I guess this also part of programming.

Happy hackin’!

Tags: stupid, php.
Categories: Programming, Development, Blablabla.
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