9:59:59.000,9:59:59.000
Hey, I am Sandi Metz and I am the

9:59:59.000,9:59:59.000
last but one speaker and that means

9:59:59.000,9:59:59.000
you have almost made it.[br][audience laughter]

9:59:59.000,9:59:59.000
You get a break, there's another keynote

9:59:59.000,9:59:59.000
if you stay for that –

9:59:59.000,9:59:59.000
it's really bright up here, I'm going to have

9:59:59.000,9:59:59.000
to look at you some. So, yeah,

9:59:59.000,9:59:59.000
you've almost arrived. Even those of you who

9:59:59.000,9:59:59.000
are new have almost survived a total RailsConf

9:59:59.000,9:59:59.000
and so I think we should – let's do this –

9:59:59.000,9:59:59.000
sponsors pay the bills, they do, we're glad. [clapping]

9:59:59.000,9:59:59.000
Thank 'em.

9:59:59.000,9:59:59.000
But even more than that

9:59:59.000,9:59:59.000
"human people" organize this conference

9:59:59.000,9:59:59.000
and if you see – this is your job before you

9:59:59.000,9:59:59.000
leave today – find someone in one of those

9:59:59.000,9:59:59.000
red shirts, and say thank you.

9:59:59.000,9:59:59.000
Alright? Let's thank 'em here.

9:59:59.000,9:59:59.000
Thank 'em in person.

9:59:59.000,9:59:59.000
Going to start my clock, I have about –

9:59:59.000,9:59:59.000
I really do have about 40 minutes.

9:59:59.000,9:59:59.000
I don't have 500 slides of code this year,

9:59:59.000,9:59:59.000
though, so… it's not going to be that bad.

9:59:59.000,9:59:59.000
Yeah, let's just go. So

9:59:59.000,9:59:59.000
I'm Sandi Metz and I'm really happy to be here

9:59:59.000,9:59:59.000
and I have a talk. This years talk is

9:59:59.000,9:59:59.000
about code smells.

9:59:59.000,9:59:59.000
This is a term invented by this guy. So

9:59:59.000,9:59:59.000
it's really, uh, we did not plan that

9:59:59.000,9:59:59.000
I would follow Katrina

9:59:59.000,9:59:59.000
but it's the perfect talk to follow her

9:59:59.000,9:59:59.000
talk. She just mentioned this guy's name.

9:59:59.000,9:59:59.000
This guy's name is Kent Beck. This guy's

9:59:59.000,9:59:59.000
Martin Fowler, he's the man who wrote

9:59:59.000,9:59:59.000
this book, which is the book

9:59:59.000,9:59:59.000
that teaches us to do refactoring.

9:59:59.000,9:59:59.000
They collaborated together on the

9:59:59.000,9:59:59.000
third chapter of that book, and

9:59:59.000,9:59:59.000
it's like naming things wins and

9:59:59.000,9:59:59.000
the name "code smell", the reason why

9:59:59.000,9:59:59.000
you know that term today is because

9:59:59.000,9:59:59.000
of what these guys did back in the 1990s.

9:59:59.000,9:59:59.000
Now,

9:59:59.000,9:59:59.000
I wrote a book a couple of years ago

9:59:59.000,9:59:59.000
– before that, I wrote code for 35 years,

9:59:59.000,9:59:59.000
I went to my desk every day and

9:59:59.000,9:59:59.000
wrote code – and now, I don't do that.

9:59:59.000,9:59:59.000
I teach. I teach classes in

9:59:59.000,9:59:59.000
object-oriented design.

9:59:59.000,9:59:59.000
And in my classes,

9:59:59.000,9:59:59.000
I have occasion to ask people

9:59:59.000,9:59:59.000
if they've heard of code smells

9:59:59.000,9:59:59.000
and just like I suspect all of you

9:59:59.000,9:59:59.000
everyone in my class always says

9:59:59.000,9:59:59.000
"Oh yeah, we know what code smells

9:59:59.000,9:59:59.000
are." And then I ask them

9:59:59.000,9:59:59.000
to list five…

9:59:59.000,9:59:59.000
and no one can.

9:59:59.000,9:59:59.000
Alright, okay, now I can hear

9:59:59.000,9:59:59.000
you trying, but really most of you cannot.

9:59:59.000,9:59:59.000
I know that, okay.

9:59:59.000,9:59:59.000
And so, we all think

9:59:59.000,9:59:59.000
we know about this term

9:59:59.000,9:59:59.000
but it doesn't mean "I don't like your

9:59:59.000,9:59:59.000
code and I can't tell you why."

9:59:59.000,9:59:59.000
That is not what a code smell is.

9:59:59.000,9:59:59.000
There is some opinion involved

9:59:59.000,9:59:59.000
but really, it's not just that I

9:59:59.000,9:59:59.000
disagree with how you wrote your code,

9:59:59.000,9:59:59.000
the standard is higher. These smells –

9:59:59.000,9:59:59.000
these 22 different smells all have

9:59:59.000,9:59:59.000
very precise meanings…

9:59:59.000,9:59:59.000
and the power, the magic if you will

9:59:59.000,9:59:59.000
of this list is they've given things

9:59:59.000,9:59:59.000
names. Once you've given a complex idea

9:59:59.000,9:59:59.000
a name, if we could just

9:59:59.000,9:59:59.000
learn what that name stood for

9:59:59.000,9:59:59.000
it means we could just talk to each other

9:59:59.000,9:59:59.000
in an unambiguous way without

9:59:59.000,9:59:59.000
having miscommunications. And so

9:59:59.000,9:59:59.000
one of the things they talk about –

9:59:59.000,9:59:59.000
very often when people talk about

9:59:59.000,9:59:59.000
code smells, they prefix "code smell"

9:59:59.000,9:59:59.000
with the word "bad".

9:59:59.000,9:59:59.000
They say "bad smells".

9:59:59.000,9:59:59.000
But really, the definition of a code

9:59:59.000,9:59:59.000
smell is that it might indicate a problem.

9:59:59.000,9:59:59.000
You don't have an obligation

9:59:59.000,9:59:59.000
to filter out all the smells,

9:59:59.000,9:59:59.000
and it's actually important that you not.

9:59:59.000,9:59:59.000
It's also worth getting familiar

9:59:59.000,9:59:59.000
with code smells because they have

9:59:59.000,9:59:59.000
such great names.

9:59:59.000,9:59:59.000
Look at this list.

9:59:59.000,9:59:59.000
"Feature Envy" – that's cool.

9:59:59.000,9:59:59.000
I like this one, the one that

9:59:59.000,9:59:59.000
needs a code of conduct:

9:59:59.000,9:59:59.000
"Innappropriate Intimacy".

9:59:59.000,9:59:59.000
"Shotgun Surgery", that's another

9:59:59.000,9:59:59.000
favourite.

9:59:59.000,9:59:59.000
And so, the problem with this list

9:59:59.000,9:59:59.000
– first of all, okay, I'll confess –

9:59:59.000,9:59:59.000
I had that book for a really long time

9:59:59.000,9:59:59.000
before I read it. I had a really

9:59:59.000,9:59:59.000
hard time with it.

9:59:59.000,9:59:59.000
It's one of those books that's

9:59:59.000,9:59:59.000
like a recipe book and I've heard

9:59:59.000,9:59:59.000
people who – it would be like reading

9:59:59.000,9:59:59.000
a cookbook if you did not eat.

9:59:59.000,9:59:59.000
And so I really need the story

9:59:59.000,9:59:59.000
arc and I had very hard time

9:59:59.000,9:59:59.000
following along, like, persisting

9:59:59.000,9:59:59.000
with a bunch of recipes that were just

9:59:59.000,9:59:59.000
like etc., etc., etc.

9:59:59.000,9:59:59.000
But it turns out

9:59:59.000,9:59:59.000
it was really worthwhile

9:59:59.000,9:59:59.000
and I finally did it and actually

9:59:59.000,9:59:59.000
Katrina made me. I have to say it.

9:59:59.000,9:59:59.000
Katrina made me.

9:59:59.000,9:59:59.000
So there's 22 things on this list.

9:59:59.000,9:59:59.000
I had a Stack Overflow at 22.

9:59:59.000,9:59:59.000
It turns out there's a guy who's name

9:59:59.000,9:59:59.000
I can't pronounce – "Mäntylä" – it'll

9:59:59.000,9:59:59.000
be in the credits, he wrote a paper

9:59:59.000,9:59:59.000
where he grouped 'em. He grouped

9:59:59.000,9:59:59.000
'em in five different categories,

9:59:59.000,9:59:59.000
and through the magic of keynote,

9:59:59.000,9:59:59.000
I can do that.

9:59:59.000,9:59:59.000
This is the only reason we make

9:59:59.000,9:59:59.000
talks, so we can use the effects.

9:59:59.000,9:59:59.000
So here, let's just talk about

9:59:59.000,9:59:59.000
of things that just do not need

9:59:59.000,9:59:59.000
to be that big.

9:59:59.000,9:59:59.000
Long methods and large classes

9:59:59.000,9:59:59.000
are probably self-explanatory.

9:59:59.000,9:59:59.000
Data Clumps is where you have

9:59:59.000,9:59:59.000
two or more pieces of data that

9:59:59.000,9:59:59.000
always appear together; pass 'em

9:59:59.000,9:59:59.000
around and in together.

9:59:59.000,9:59:59.000
Long parameter list is obvious.

9:59:59.000,9:59:59.000
It might only occur once, but if

9:59:59.000,9:59:59.000
it's long enough, there's probably an

9:59:59.000,9:59:59.000
object in there somewhere.

9:59:59.000,9:59:59.000
And this other wonderfully named

9:59:59.000,9:59:59.000
thing called "Primitive Obsession", we saw

9:59:59.000,9:59:59.000
an example of that in the talk Katrina

9:59:59.000,9:59:59.000
just gave. This is like when you have

9:59:59.000,9:59:59.000
an instance of a base class

9:59:59.000,9:59:59.000
like a String, or a Number, or a Hash

9:59:59.000,9:59:59.000
or an Array, and you pass it

9:59:59.000,9:59:59.000
around to a bunch of objects

9:59:59.000,9:59:59.000
and they look at it and decide on what

9:59:59.000,9:59:59.000
to do based on something that

9:59:59.000,9:59:59.000
they know about it.

9:59:59.000,9:59:59.000
So you say, "I got a number,

9:59:59.000,9:59:59.000
it's six so I'll do thing X" or

9:59:59.000,9:59:59.000
"it's eight, I'll do something else."

9:59:59.000,9:59:59.000
If only the thing you got was

9:59:59.000,9:59:59.000
smarter, you could just send

9:59:59.000,9:59:59.000
it messages, so Primitive Obsession

9:59:59.000,9:59:59.000
is when the objects are too dumb

9:59:59.000,9:59:59.000
that you're passing around.

9:59:59.000,9:59:59.000
These things are grouped into

9:59:59.000,9:59:59.000
a category called "Bloaters".

9:59:59.000,9:59:59.000
They make code bigger than it needs to be

9:59:59.000,9:59:59.000
in the places where they use them.

9:59:59.000,9:59:59.000
The next group, this one,

9:59:59.000,9:59:59.000
these are ideas that are available in

9:59:59.000,9:59:59.000
object-oriented programming that you

9:59:59.000,9:59:59.000
can misuse.

9:59:59.000,9:59:59.000
Switch statements, you know they're

9:59:59.000,9:59:59.000
conditionals in normal people talk.

9:59:59.000,9:59:59.000
"Refused Bequest" is when it's an

9:59:59.000,9:59:59.000
inheritance problem. You have a subclass

9:59:59.000,9:59:59.000
that overrides a method that it

9:59:59.000,9:59:59.000
inherits from a superclass, and

9:59:59.000,9:59:59.000
throws an exception and says

9:59:59.000,9:59:59.000
like "I don't implement that thing."

9:59:59.000,9:59:59.000
"I refuse the bequest."

9:59:59.000,9:59:59.000
"Alternative Classes with Alternative

9:59:59.000,9:59:59.000
Interfaces" is pretty obvious.

9:59:59.000,9:59:59.000
The other thing is the Temporary Field –

9:59:59.000,9:59:59.000
it's interesting that Temporary Field is

9:59:59.000,9:59:59.000
on this list, right? Temporary Fields can

9:59:59.000,9:59:59.000
be really handy, but sometimes

9:59:59.000,9:59:59.000
they mean that you should have

9:59:59.000,9:59:59.000
made a method with that name, right?

9:59:59.000,9:59:59.000
Why are you giving it a name?

9:59:59.000,9:59:59.000
What is it about the code that you have

9:59:59.000,9:59:59.000
now that feels like it needs that name?

9:59:59.000,9:59:59.000
And so these things are all grouped

9:59:59.000,9:59:59.000
in a category that he called "Tool

9:59:59.000,9:59:59.000
Abusers". I work on a lot of

9:59:59.000,9:59:59.000
bikes, I have a garage full of bikes

9:59:59.000,9:59:59.000
and I'm an amateur mechanic

9:59:59.000,9:59:59.000
which means I have amateur tools

9:59:59.000,9:59:59.000
which sometimes involves a very short

9:59:59.000,9:59:59.000
wrench, a very long pipe, and a

9:59:59.000,9:59:59.000
hammer.

9:59:59.000,9:59:59.000
I can tell you that it almost always

9:59:59.000,9:59:59.000
turns out badly if you abuse your tools.

9:59:59.000,9:59:59.000
Alright, next. This group

9:59:59.000,9:59:59.000
this is stuff that makes change hard.

9:59:59.000,9:59:59.000
So "Divergent Change", "Shotgun

9:59:59.000,9:59:59.000
Surgery" – which we've talked about –

9:59:59.000,9:59:59.000
"Parallel Inheritance Heirarchies"

9:59:59.000,9:59:59.000
which is pretty obvious – sometimes

9:59:59.000,9:59:59.000
you have a couple of heirarchies

9:59:59.000,9:59:59.000
that each have two sides, and

9:59:59.000,9:59:59.000
every time you change something

9:59:59.000,9:59:59.000
you gotta go add or move

9:59:59.000,9:59:59.000
in both sides of the heirarchy.

9:59:59.000,9:59:59.000
These are the kind of things

9:59:59.000,9:59:59.000
that keep you from wanting

9:59:59.000,9:59:59.000
to change code or make code

9:59:59.000,9:59:59.000
hard to change. Now, notice that

9:59:59.000,9:59:59.000
almost everything that I'm talking

9:59:59.000,9:59:59.000
about… if nothing ever changes,

9:59:59.000,9:59:59.000
it's probably okay. Like, code that's

9:59:59.000,9:59:59.000
– really embarrasing code –

9:59:59.000,9:59:59.000
it's fine to keep that really embarrasing

9:59:59.000,9:59:59.000
code, you should be brave about

9:59:59.000,9:59:59.000
your ugly, embarrasing code

9:59:59.000,9:59:59.000
because it is not costing you money

9:59:59.000,9:59:59.000
if it's not changing. And so,

9:59:59.000,9:59:59.000
just because these smells exist,

9:59:59.000,9:59:59.000
you know, sometimes you should

9:59:59.000,9:59:59.000
just, like, own 'em. Be proud.

9:59:59.000,9:59:59.000
Walk away.

9:59:59.000,9:59:59.000
Don't let people make fun of you

9:59:59.000,9:59:59.000
for having bad code.

9:59:59.000,9:59:59.000
This next category…

9:59:59.000,9:59:59.000
"Lazy Class", "Speculative Generality" –

9:59:59.000,9:59:59.000
okay, on top of the effects

9:59:59.000,9:59:59.000
finding the pictures is also fun –

9:59:59.000,9:59:59.000
classes that don't do enough is a

9:59:59.000,9:59:59.000
lazy class, it doesn't justify its

9:59:59.000,9:59:59.000
existence. I'm going to skip Speculative

9:59:59.000,9:59:59.000
Generality for a minute. Data Class,

9:59:59.000,9:59:59.000
you know, we're object-oriented

9:59:59.000,9:59:59.000
programmers, classes oughta have data

9:59:59.000,9:59:59.000
and behaviour. Duplicated Code is

9:59:59.000,9:59:59.000
pretty obvious. Let me go back to

9:59:59.000,9:59:59.000
Speculative Generality.

9:59:59.000,9:59:59.000
I'm going to ask you to raise your hands

9:59:59.000,9:59:59.000
again. Who in here has ever

9:59:59.000,9:59:59.000
written some code for a feature you

9:59:59.000,9:59:59.000
thought might arrive in the future.

9:59:59.000,9:59:59.000
Keep your hands up for a minute.

9:59:59.000,9:59:59.000
Alright, I'm going to out myself

9:59:59.000,9:59:59.000
with you here.

9:59:59.000,9:59:59.000
Who in here has ever, after many

9:59:59.000,9:59:59.000
months of working around that code

9:59:59.000,9:59:59.000
ripped it out and thrown it

9:59:59.000,9:59:59.000
away? <i>chuckles</i> Yeah, okay.

9:59:59.000,9:59:59.000
We are bad guessers, and

9:59:59.000,9:59:59.000
you know, I love OO,

9:59:59.000,9:59:59.000
I love object-oriented design,

9:59:59.000,9:59:59.000
it's a thing that really interests me,

9:59:59.000,9:59:59.000
but this thing of Speculative Generality,

9:59:59.000,9:59:59.000
where we say, I'm going to do something

9:59:59.000,9:59:59.000
really cool in my code for some feature

9:59:59.000,9:59:59.000
I <i>think</i> we might need later…

9:59:59.000,9:59:59.000
this is why people say bad things

9:59:59.000,9:59:59.000
about OO. Right? This is what

9:59:59.000,9:59:59.000
they blame us for. It's primarily

9:59:59.000,9:59:59.000
things in that category.

9:59:59.000,9:59:59.000
You have to be right. The few times

9:59:59.000,9:59:59.000
that you are right have to <i>really</i>

9:59:59.000,9:59:59.000
be big wins that way the enormous

9:59:59.000,9:59:59.000
cost of being wrong – code is read

9:59:59.000,9:59:59.000
many more times than it is written.

9:59:59.000,9:59:59.000
The reason why we cost money

9:59:59.000,9:59:59.000
is the time spent reading code.

9:59:59.000,9:59:59.000
And if you add generality, you

9:59:59.000,9:59:59.000
increase the level of abstraction

9:59:59.000,9:59:59.000
of code. Very often that means

9:59:59.000,9:59:59.000
adding levels of indirection

9:59:59.000,9:59:59.000
which humans are terrible at

9:59:59.000,9:59:59.000
and every time you look at that code

9:59:59.000,9:59:59.000
it means its harder to understand.

9:59:59.000,9:59:59.000
So we should really try to

9:59:59.000,9:59:59.000
restrain ourselves, and not speculate

9:59:59.000,9:59:59.000
about the future. When the new

9:59:59.000,9:59:59.000
requirements come in, they'll tell us

9:59:59.000,9:59:59.000
how we wish we'd written the code

9:59:59.000,9:59:59.000
and we can do it then.

9:59:59.000,9:59:59.000
Dispensables. Sorry, here.

9:59:59.000,9:59:59.000
Ah, see I did that thing with the clicker!

9:59:59.000,9:59:59.000
Dispensables, okay, you've all

9:59:59.000,9:59:59.000
seen that now so we'll move on.

9:59:59.000,9:59:59.000
So the last category here is this group.

9:59:59.000,9:59:59.000
"Feature Envy", "Inappropriate Intimacy",

9:59:59.000,9:59:59.000
"Message Chains", and "Middle Man".

9:59:59.000,9:59:59.000
Feature Envy is when I have an object

9:59:59.000,9:59:59.000
uh, Joe down here is an object,

9:59:59.000,9:59:59.000
Joe's an object that I know about

9:59:59.000,9:59:59.000
and I send him way more messages

9:59:59.000,9:59:59.000
than I send myself. Could be

9:59:59.000,9:59:59.000
that I'm more tightly coupled to

9:59:59.000,9:59:59.000
Joe than I know, right?

9:59:59.000,9:59:59.000
Inappropriate Intimacy would be

9:59:59.000,9:59:59.000
when Joe had a bunch of private

9:59:59.000,9:59:59.000
methods and I reached in and

9:59:59.000,9:59:59.000
got them, okay, that would be bad.

9:59:59.000,9:59:59.000
<i>laughs</i> I really am sorta pushing

9:59:59.000,9:59:59.000
the code of conduct, aren't I?

9:59:59.000,9:59:59.000
I hope no-one was made uncomfortable

9:59:59.000,9:59:59.000
by that. Message Chains – there's

9:59:59.000,9:59:59.000
the Law of Demeter, those violations

9:59:59.000,9:59:59.000
right? You got dots. You send

9:59:59.000,9:59:59.000
messages to something you know about

9:59:59.000,9:59:59.000
and you get a response and you send

9:59:59.000,9:59:59.000
a message to that. If the types

9:59:59.000,9:59:59.000
change across those dot changes

9:59:59.000,9:59:59.000
that's a Message Chain.

9:59:59.000,9:59:59.000
Middle Man is if you have

9:59:59.000,9:59:59.000
an object that you send messages to

9:59:59.000,9:59:59.000
and it's sole purpose in life is to

9:59:59.000,9:59:59.000
forward those messages to somebody else

9:59:59.000,9:59:59.000
maybe you don't need that object.

9:59:59.000,9:59:59.000
These things are grouped together

9:59:59.000,9:59:59.000
in a group called "Couplers"

9:59:59.000,9:59:59.000
because the effect of this

9:59:59.000,9:59:59.000
is that it binds the objects together

9:59:59.000,9:59:59.000
such that even if they're

9:59:59.000,9:59:59.000
beautiful, even if you've tested

9:59:59.000,9:59:59.000
'em, even if they're little

9:59:59.000,9:59:59.000
works of art, you can't ever

9:59:59.000,9:59:59.000
reach in and get one out

9:59:59.000,9:59:59.000
and use it in another context.

9:59:59.000,9:59:59.000
They come as a bundle, all or nothing.

9:59:59.000,9:59:59.000
And so there you go.

9:59:59.000,9:59:59.000
10 minutes and 34 seconds

9:59:59.000,9:59:59.000
everything you need to know about

9:59:59.000,9:59:59.000
code smells.

9:59:59.000,9:59:59.000
Okay, but we're not done.

9:59:59.000,9:59:59.000
Now I'm going to talk about refactoring

9:59:59.000,9:59:59.000
but not very much

9:59:59.000,9:59:59.000
because you just heard a talk

9:59:59.000,9:59:59.000
on refactoring.

9:59:59.000,9:59:59.000
But there's a thing here

9:59:59.000,9:59:59.000
that people don't know,

9:59:59.000,9:59:59.000
that those guys discovered in the 90s,

9:59:59.000,9:59:59.000
that I want you to go away today

9:59:59.000,9:59:59.000
understanding, and it's this:

9:59:59.000,9:59:59.000
refactorings, just like code smells have

9:59:59.000,9:59:59.000
names and they mean very specific

9:59:59.000,9:59:59.000
things, refactorings have names

9:59:59.000,9:59:59.000
they're very specific, and they

9:59:59.000,9:59:59.000
come with recipes. Not hand-wavy

9:59:59.000,9:59:59.000
recipes, very, very specific, concrete

9:59:59.000,9:59:59.000
recipes. Here's one.

9:59:59.000,9:59:59.000
This is page 149 of Martin Fowler's

9:59:59.000,9:59:59.000
book, and it looks like a recipe, right?

9:59:59.000,9:59:59.000
It has numbers down the side.

9:59:59.000,9:59:59.000
There's little optional clauses here

9:59:59.000,9:59:59.000
for situations that might be different in

9:59:59.000,9:59:59.000
your case. You notice that it refers

9:59:59.000,9:59:59.000
to other recipes, here where the

9:59:59.000,9:59:59.000
things are in capital letters, that's

9:59:59.000,9:59:59.000
another whole recipe by itself.

9:59:59.000,9:59:59.000
It's recipes and recipes

9:59:59.000,9:59:59.000
within recipes.

9:59:59.000,9:59:59.000
All of the refactorings work in the

9:59:59.000,9:59:59.000
same way. This is not something –

9:59:59.000,9:59:59.000
we don't wave our hands and say

9:59:59.000,9:59:59.000
"go refactor" – refactoring has a

9:59:59.000,9:59:59.000
very specific definition, it's to

9:59:59.000,9:59:59.000
rearrange code without changing its

9:59:59.000,9:59:59.000
behaviour and all the ways

9:59:59.000,9:59:59.000
in which you can rearrange code are

9:59:59.000,9:59:59.000
already written down, with instructions

9:59:59.000,9:59:59.000
by people who really thought a lot

9:59:59.000,9:59:59.000
about this. And so now you know

9:59:59.000,9:59:59.000
code smells have names, and they're

9:59:59.000,9:59:59.000
real things, and refactorings have names

9:59:59.000,9:59:59.000
and they're real things, and they

9:59:59.000,9:59:59.000
come with recipes. I can give you

9:59:59.000,9:59:59.000
one last bit of news. Every code smell

9:59:59.000,9:59:59.000
maps to the Curative Refactoring Recipe.

9:59:59.000,9:59:59.000
Ponder that for a minute.

9:59:59.000,9:59:59.000
What does that mean?

9:59:59.000,9:59:59.000
Here's a cheat sheet. This one's

9:59:59.000,9:59:59.000
provided by the guys at Industrial

9:59:59.000,9:59:59.000
Logic. Notice at the top that the code

9:59:59.000,9:59:59.000
smell they're talking about is Data

9:59:59.000,9:59:59.000
Clumps. This is a little tiny definition

9:59:59.000,9:59:59.000
of a Data Clump. "[F 81]" is a

9:59:59.000,9:59:59.000
reference to page 81 in Martin

9:59:59.000,9:59:59.000
Fowler's book. The three things

9:59:59.000,9:59:59.000
on the bottom are the

9:59:59.000,9:59:59.000
refactoring recipes that are curative

9:59:59.000,9:59:59.000
for that code smell.

9:59:59.000,9:59:59.000
So this slide, I just blew it up

9:59:59.000,9:59:59.000
so you could see it,

9:59:59.000,9:59:59.000
I just extracted it from this PDF

9:59:59.000,9:59:59.000
which is a couple pages long. It

9:59:59.000,9:59:59.000
cross-references all the code smells

9:59:59.000,9:59:59.000
and refactorings in Martin Fowler's

9:59:59.000,9:59:59.000
book and also a book by

9:59:59.000,9:59:59.000
another guy named Joshua Kerievsky

9:59:59.000,9:59:59.000
called <i>Refactoring to Patterns.</i>

9:59:59.000,9:59:59.000
It turns out that this is all

9:59:59.000,9:59:59.000
you need to know. The problem

9:59:59.000,9:59:59.000
is solved. You do not have to

9:59:59.000,9:59:59.000
reinvent this wheel.

9:59:59.000,9:59:59.000
All you need to know is a few things.

9:59:59.000,9:59:59.000
And many of you –

9:59:59.000,9:59:59.000
at least, my experience –

9:59:59.000,9:59:59.000
the reason I wanted to give this talk

9:59:59.000,9:59:59.000
from my experience teaching is

9:59:59.000,9:59:59.000
somehow a generation has passed

9:59:59.000,9:59:59.000
since all these books were written, and

9:59:59.000,9:59:59.000
that people new to programming

9:59:59.000,9:59:59.000
in the last 15 years –

9:59:59.000,9:59:59.000
I'm a woman of a certain age,

9:59:59.000,9:59:59.000
you can tell –

9:59:59.000,9:59:59.000
if you're new in the last 15 years

9:59:59.000,9:59:59.000
you may not have this information.

9:59:59.000,9:59:59.000
I'm going to show you some code now.

9:59:59.000,9:59:59.000
I'm going to use the last 15-20 minutes

9:59:59.000,9:59:59.000
looking at code, and I'm going to

9:59:59.000,9:59:59.000
show you the practical effect of

9:59:59.000,9:59:59.000
recognizing code smells and doing

9:59:59.000,9:59:59.000
refactorings.

9:59:59.000,9:59:59.000
My class Sale is a subclass of

9:59:59.000,9:59:59.000
Persistence. You can think of that as

9:59:59.000,9:59:59.000
ActiveRecord. If you're in the back it

9:59:59.000,9:59:59.000
won't hurt my feelings if you get up

9:59:59.000,9:59:59.000
and come forward – that's the font

9:59:59.000,9:59:59.000
size of my code.

9:59:59.000,9:59:59.000
I didn't know I was gonna be in the

9:59:59.000,9:59:59.000
keynote, man, it just happened.

9:59:59.000,9:59:59.000
Let's say I have my class Foo that has

9:59:59.000,9:59:59.000
a sales_total method, takes some params,

9:59:59.000,9:59:59.000
and maybe this a controller-like thing

9:59:59.000,9:59:59.000
or something that a controller calls.

9:59:59.000,9:59:59.000
It knows the name of the Sale class and

9:59:59.000,9:59:59.000
it knows some other things, right?

9:59:59.000,9:59:59.000
It knows that Sale understands where

9:59:59.000,9:59:59.000
and it knows that the thing that comes

9:59:59.000,9:59:59.000
back as a response from sending the where

9:59:59.000,9:59:59.000
message knows sum.