WEBVTT

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In this session
we'll look at what Pharo is.

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It's a pure object language.

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But it's also an IDE,
an integrated development environment.

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It's inspired by Smalltalk.
That's its spiritual father.

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It's a powerful and elegant language
that's fun to program.

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There's a great community of people
who do a variety of things with it.

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What we'll try to teach you on
this course, with the help of videos,

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is that it's a living system
you can script as you go.

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You can take Pharo with its MIT
licence and do what you want with it.

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When I say that Pharo is elegant
I have arguments to back that up.

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The syntax fits on a postcard

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and the simple
and powerful object model

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takes up four lines.
I'll show you...

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On this slide
you have the full Pharo syntax.

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I mean "full", there's nothing else.

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That doesn't mean you can understand
the syntax just by reading this slide.

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We'll have several sessions,
deciphering

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and helping you understand
how the syntax is structured.

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But it gives you an idea
of the work to be done.

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There's nothing else
but this syntax.

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Likewise, the object model
is summed up on that slide.

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Everything is dynamically typed,

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everything is an object instance
of a class,

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all methods are public virtual,
all attributes are protected,

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and there's single inheritance.

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There's no boxing,
no primitive and non-primitive type,

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no generic type, and so on.

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You have everything.

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You just saw
the Pharo syntax and model.

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We'll come back to that,

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but it's just to give you an idea
of the system's complexity.

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You have to realise that Pharo
is entirely written in itself.

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What do I mean by Pharo?
I mean the strings, characters,

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booleans, IDE, compiler, sockets...

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Everything is written in Pharo.

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So if you master this syntax,
written on one page, and this model,

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then you'll have access
to the entirety of Pharo.

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I think that this is exciting
intellectually

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because you have
this tiny entrance door

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into a gigantic world.

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So if you look
at the title of this mooc,

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it includes the word "immersive".
Why is this?

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Because Pharo isn't a blackbox.

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The entire system
is fully inspectable,

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so you can go and see
how it's implemented.

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And Pharo is reflective.

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It has a representation of itself

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that you can use
in order to understand it.

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This means you can get completely
immersed in a world of objects.

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I like this metaphor of the fish tank.

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A language is usually a blackbox.

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Pharo isn't a blackbox,
it's a fish tank,

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where you can see the objects
and constituents of the system itself,

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but you can also dive into the tank
and interact with the objects.

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So it's really in that sense

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that we're inviting you
to play with Pharo.

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Here I'm showing you an example
of an immersive system.

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What we call immersive
or interactive.

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On the left you have the code.
On the right, what it produces.

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Each time the programmer
presses the compilation key,

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the screen goes blue
and the result is on the right.

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He's constantly modifying his code

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and seeing what he's doing
in the right-hand window.

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You can do this
with any element of the system,

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whether it's a socket, a file...

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3D, like here.
But a web server would be the same.

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The web server functions
and you can modify it as you go.

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Now I'll show you
the supports available

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if you want to work Pharo
outside this mooc.

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There are several books,
all open source.

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There's <i>Pharo by Example</i>,
for beginners, in several languages.

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It's currently being updated
for Pharo 5.

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<i>Deep into Pharo </i>is more advanced,

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going into the libraries,

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into less-known aspects
of the language and the tools.

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There's
<i>Enterprise Pharo, a Web Perspective,</i>

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which puts the emphasis
on web libraries,

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like WebSockets,
HTTP/HTTPS servers

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and templating.

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They're all open source.

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What we'll use mainly for this course
is a web framework, <i>Seaside</i>.

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You have 300 pages available
at the indicated address.

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You can read the book
if you want to know more.

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But we'll give you all you need
to follow the mooc

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without having to read the book too.

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For those interested
in other aspects,

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there's this book of about 300 pages
about the numerical methods in Pharo,

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going from things
like statistical series,

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to iterative algorithms and clustering.

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I told you that Pharo
is a system to learn from.

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I'll give you a few illustrations.

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We'll see them again
in the videos.

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Every graphic element of Pharo
that you click on...

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With Cmd+Shift+Option,

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you'll get a little menu
around the graphic element.

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By using these menus,
you can go directly inside

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and manipulate the visual elements
you're dealing with.

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We'll show you what
an Inspector is,

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an object that lets you manipulate
the properties of other objects,

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and start to implement them.

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We also have an object
called a Finder.

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So I can ask the Finder

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to find all the system's methods
that contain the word "match".

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It shows me a list, and I can access
the method's code directly.

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There's also a tool called Spotter,
which you get with Shift+Enter.

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And you tell it what you want.

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Spotter will help you find
classes, methods or resources.

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You'll have videos
to explain all that.

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But, again,
Spotter is written in Pharo itself.

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The Finder has quite a nice function,

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when you start learning Pharo.

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There'll be a video about this too.

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You can give examples and say:

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"This is what I want to do but I don't
know how to write it in Pharo."

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The Finder will look for methods.

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I have an example.

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I say: "I have two strings, AB and C.
I'd like to concatenate them."

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And I know that the result
should be the string ABC.

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It sounds simple.

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So I say to the system:

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"Give me the message,
if one exists,

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"which will let me
concatenate these strings."

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And that's what you can see here.

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It says “,” is a method implemented
in SequencableCollection.

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This will be sent to my first string,

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and I'll get my third string.

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You'll be able to use this Finder
on examples,

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to make you quicker in Pharo.

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In this Mooc we'll talk
about object oriented design, which is part

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of the DNA of Pharo.

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People who program in Pharo
think OO in an elegant way.

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I'll show you the exercises
we'll be presenting.

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We're often asked
how not is implemented.

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People often wonder
if this is an interesting question.

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It is interesting because
fundamental rules result from it.

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It'll be part of the exercise.

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Once you have Pharo
and you see how not is implemented,

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you'll start thinking
in a different way.

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This really is part of the culture
of people who use Pharo:

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to think a design
in a really elegant way.

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You can install Pharo
as described on the Pharo website.

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Of course, during the MOOC
and on the FUN site,

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you'll get all the instructions

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for installing Pharo on any system.

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Pharo is very easy to install,

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as a drag and drop,
onto any OS.