li #[a(href="https://dry-python.org/") dry-python.org]

li Django Channels 1.0

li 5 years of experience in Python

section

h2 pros

ol

ol

li.fragment Really hard to change

li.fragment We can not see the whole picture

section

h2 Implicit API

pre

li.fragment Python vs. Go

li.fragment Emacs vs. Vim

li.fragment Tabs vs. Spaces

section

section

h2 What is the domain-driven design?

p.fragment Focus on the core complexity and opportunity in the domain

p.fragment Explore models in a collaboration of domain experts and software experts

p.fragment Write software that expresses those models explicitly

p.fragment Speak #[b ubiquitous language] within a #[b bounded context]

section

h2 What is a model?

p.fragment #[b HINT:] Not a UML diagram

a(href="https://dry-python.org/") dry-python

p A set of libraries for pluggable business logic components.

img(src="https://raw.githubusercontent.com/dry-python/brand/master/logo/dry-python.png").plain

section

img(src="https://raw.githubusercontent.com/dry-python/brand/master/logo/stories.png").plain

p Define a user story in the business transaction DSL.

li.fragment Each step knows nothing about a neighbor

li.fragment Easy reuse of code

li.fragment Allows to instrument code easily

h2 DEBUG TOOLBAR

br

br

br

br

br

h2(style="color: white") py.test

h2 Sentry

h2 ELK

section

ul

li.fragment We do not have the tooling to work with data

li.fragment There are no data contracts written in code

section

section

h2 Layout

pre

h2.fragment cons

ol

li.fragment Working with data sources manually

section

img(src="https://raw.githubusercontent.com/dry-python/brand/master/logo/mappers.png").plain

p Declarative mappers from ORM models to domain entities. And back again!

}

""", {"id": id}))

section

section

h2 How we use third-party libraries

pre

"private-user-1"

)

section

section

h2 How to use it with DI

pre

load_profile = app.repositories.load_profile

MakePurchase.make_purchase(category_id=1, price_id=1)

section

h2 Get in touch

ul

h2 Complexity

p.fragment #[b Accidental complexity] refers to challenges that developers unintentionally make for themselves as a result of trying to solve a problem.

p.fragment #[b Essential complexity] is just the nature of the beast you're trying to tame.

section

h2 Accidental complexity

ul

li.fragment Emacs vs. Vim

li.fragment Tabs vs. Spaces

section

section

h2 What is the domain-driven design?

p.fragment Focus on the core complexity and opportunity in the domain

p.fragment You have to master the tool first then you can focus on #[b DDD].

p.fragment In most domain models, most design patterns are technical noise.

section

section

h2 What is a model?

p.fragment #[b HINT:] Not a UML diagram

a(href="https://dry-python.org/") dry-python

p A set of libraries for pluggable business logic components.

img(src="https://raw.githubusercontent.com/dry-python/brand/master/logo/dry-python.png").plain

section

img(src="https://raw.githubusercontent.com/dry-python/brand/master/logo/stories.png").plain

p Define a user story in the business transaction DSL.

user = #{"<"}User: 3292#{">"} # Story argument

category = #{"<"}Category: 1318#{">"}

# Set by Subscription.find_category

h2 DEBUG TOOLBAR

br

br

br

br

br

h2(style="color: white") py.test

h2 Sentry

h2 ELK

section

h2 Layout

pre

class Order:

primary_key: OrderId

items: List[LineItem]

section

img(src="https://raw.githubusercontent.com/dry-python/brand/master/logo/mappers.png").plain

p Declarative mappers from ORM models to domain entities. And back again!

loadInvoice(id: %(id)d)

}

""", {"id": id}))

section

h2 Tests & Mocks

pre

li.fragment Contracts and aggregates

li.fragment Mappers

li.fragment Dependency injection

section

h2 Questions?

p.fragment

b and frustrating

p.fragment Let's consider we're developing subscription button for a web service

h2(style="color: white; background-color: black") Startup

br

br

Traceback (most recent call last):

File "views.py", line 1027, in buy_subscription

ZeroDivisionError: division by zero

h2(style="color: white; background-color: black") Enterprise

br

br

ol

li.fragment What exactly does this class do?

li.fragment How to use it?

br

section

h2 Framework internals leak

li.fragment Hard to reason about

li.fragment Time-consuming

section

section

blockquote

p If your code is crap, stickies on the wall won't help.

a(href="https://twitter.com/henrikkniberg").

@HenrikKniberg

section

h2 Service layer

p Defines an application's boundary with a layer of services that establishes a set of available operations and coordinates the application's response in each operation.

user = #{"<"}User: 3292#{">"} # Story argument

category = #{"<"}Category: 1318#{">"}

# Set by Subscription.find_category

h2 DEBUG TOOLBAR

br

br

br

br

br

h2(style="color: white") py.test

h2 Sentry

section

h2 Usage