All right, good morning people.
After a bright talk this morning by Ajey, it's
time to get dark and dirty, OK. So I'm
from Josh Software, and it started in 2007. These
are my Twitter handles. And I'm also an author.
I have a couple of books which are out.
Well it doesn't look so dark anymore, does it?
So what is my talk gonna be about? Don't
worry. It's not gonna be anything scary. I love
Ruby. But as with every marriage, and I hope
there's no Ruby in the crowd - OK. As
with every marriage you also need to know the
other side. You know the side you were -
you didn't know when you were just going around.
But it's the same thing with Ruby. You have
to know what you're looking at. And my talk
is going to be about the weirdness and the
gotcha moments. In short, in my talk, if you
find 'Ah-ha!' moments, it's working. Oh, we have a
varied audience today. So to ensure sanity, I have
tagged my slides. My slides are tagged with my
good friend bumblebee to keep it neutral, that these
are for beginners. So you must pay attention. And
the experts, try to give the beginners a chance
to give the answer. And the experts, you know,
take your inspiration from Optimus Prime. And the beginners
can choose to tune out, but whatever you learn,
the better. So let's get started with the infamous
infinity. Now, we all know what infinity is, right?
And since we are all programmers, obviously we should
know the answer to this one. What's the answer?
There are no surprises here. No surprises there. No
division by zero. We know this. What about, what
about this? Oops. This actually works. So we know
that everything in Ruby is an object. So that
looks like a, that looks like a class. So
let's see what the hell that is anyway. If
you type this out, what do you think I
get? So... what's going on here? So infinity is
a constant define in the float class. Where do
you see it, you don't see it there. I
can use this constant to form range comparisons. I
can use it with equality operators and stuff like
that. Imagine three equal to equal to infinity. But
it works. Oh well. So. This is the way
I get people warmed up. Let's do something with
more of an adrenaline rush. Base conversions. It's a
lot of fun. So what do you think is
the output of this particular thing? Now, I don't
want all the math geeks going to their calculators,
but essence is converting a number to a string
in the octal format. So again, no surprises. Should
be fine. But let's push the tempo. Now what?
That, actually works. The next time you are reading
about, and you hear a name like getafix, ??
(00:03:57:07). You know oblix, asterix. It need not be
a name, it could be a number. Well, now
what? Push the limits. Oops. So now if you
look at it a little logically, the radix as
a portion ?? (00:04:15:18) is supported only in thirty-six,
because you have twenty-six alphabets and ten digits. So
it can go only up to a radix of
thirty-six. So if there are some innovators out there,
who want to actually get a new alphabet into
the English dictionary, we could probably have a radix
of thirty-seven. OK. Let's move on to the star.
Not the rock star, but the star operator. And
to start with, let's see what it has to
do with Splat Expander. Oh boy, we see more
and more of Ruby code right now. So what
do you think is name and occupation here? As
we can see we have a struct which takes,
which has two somethings, name and occupation, and I
create an object off the struct. Now what do
we see? Nothing fancy. We're still good. Right? So
the Splat Expander is actually taking my arguments and
given me the right name and the right occupation.
But we don't do things like this, do we?
We usually - we are Rails programmers. We work
in Rails, so we usually have stuff like this.
We use keyword arguments. We all have keyword arguments
to initiate a class like this and stuff. What
is the output now? It's Optimus Prime, so, the
experts? What is name and occupation? Here it's changed.
That's because the struct always has an array of
arguments. It does not differentiate between this. This will
not work on a class. Well, let's get to
something more funny. What about this? How many here
have used this before? We know how to convert
an array into hash. How many of you have
used this notation before? All right-y, I have two
people in the audience. Excellent. What happens now? What
does this do? It actually converts to a hash.
And out of curiosity what if I add a
seventh element in the array? Error. No like, dude,
I don't know what to do, what should I
do with the last one? Well, let's try some
more stars. Who all thinks that the output of
this is gonna be three, six, and nine? Who
all think otherwise? What's the output? Awesome. And now?
That was easy wasn't it? Now what? String ??
(00:07:04:24). That's all actually works. And let's take it
to the next level. How many here know about
Stabby, Stabby proc? Here is a sample. So this
is a Stabby proc that we have which takes
- note we are still working with star. So
if I make an invocation ?? (00:07:23:07) to the
block like this, what is the output? Mumbling, mumbling,
mumbling. It's five. And now you say, I knew
that. Right. So basically the short form for the
first, second last, last, and the rest of the
stuff is in the middle. Pretty helpful thing to
know. This works on all. It not, it's just
not worked with the Stabby proc, it'll work with
Lambda, it'll work with a method, too. But, as
with Ruby, and, if I'm supposed to be standing
here and I'm supposed to be lecturing you on
all this, I'm supposed to know my stuff. Lo
and behold, when I was trying these experiments, I
learned something new. What do you think is the
output of that? That actually works, and I have
freaking no idea how. So, well let's put in
the slide, and if I have somebody looking explain
to me how does that dot notation just work?
And it works only on this. It will not
work on a method obviously, right. But it works!
So, welcome to the weirdness of Ruby. Well. Getting
onto really complex stuff. Case statements. How many of
you have - you all have used cases, right?
Case when and stuff like that. Why do you
think this works? And I've tried to make the
example as complex as possible. All right. If Optimus
Prime doesn't do this who the hell else would,
right? So what is the output? It's pretty obvious
that we have a multiple of three, because nine
is a multiple of three, and yeah, because we
can all read in English and Ruby gives us
readable code. We know the output here, right? Well
it's true. You're absolutely right. Ruby's not that weird.
It'll give you the right answers. But my question
is: multiple_of is a method, right? It takes one
parameter, which I have passed. How was it compared
with nine? Where did nine come into the picture?
Behind every case, behind every successful case, is a
case equality operator. So what actually happens is that
that number nine is used with a case equality
operator. And that case equality operator is an alias
to the proc call, which actually gets us our
output. Well. Though this seems pretty straightforward, it has
just given me immense power. I can now manipulate
any way that I want a case equality operator
to work. Simply by over riding the equal to
equal to equal to method - the case equality
operator. And I am good to have any sort
of case comparisons that I want to make. I
don't care what happens, but it's my call anymore,
right. Speaking of case equality operator, let's go to
equality. How many of you all know these symbols?
There are operators, an eql question mark, and equal
question mark. Let's have some fun. Any takers? Who
all think the output is true? Who all think
the output is false? What happened to the rest
of the people? Don't care. Don't care. That's bad
for a conference. You know we just got a
huge lecture about participation! Again, who all thinks it's
true? Who all think it's false? Why? Oh, come
on man, Ruby's gonna be really neat. Of course
it's true. Well, what do you think now? Anybody
think it's true? All right man. Stand up dude.
Please give him a welcome, because he's got it
absolutely right. What the hell happened to the rest?
Dude, we just saw the slide before about case
equality. Are you telling me if you use that
in a when statement it's not gonna work? Of
course it's gonna work. You're just comparing to one.
And... now what? True? How many people think it's
true? How many people think it's false? Why? So
people called false but thought it was true but
didn't want to answer. Well it's false, and I've
got you guys so motivated you don't want to
answer, right. Damn it. But this is actually equality
by value. So the value returned by the object
is one, the value returned by the float is
a floating point one. It's completely different. Now what?
Now it's interesting. Why is it false? Somebody said
very confidently, why is it false? Absolutely. Now here's
the weirdness. This stuff actually compares the object ID
of the two, and a integer and a float
would have two different object IDs. It's obvious, right
fellas? So. Aiy aiy aiy, true false, what's it
guys? There string 'a' and string 'a' are two
different ruby objects. If I switch that two a
symbol - thank you that's where you go. So
with that, let's hit the jackpot. How many of
you all know what curry is? It's a lot
of fun, a lot of fun. But to make
it funnier, I actually decided let's have the slot
machine get three pulls. And I wrote code for
it on my flight here, so I have no
idea whether that's correct or wrong, but like, we
know it seems a little weird though. I've tried
to compare if all the three pulls are equal
and then I'm preparing some recipe with curry, and
do you think it would work? It just looks
a little bit of weird code, but I shall
explain. So curry is a method in the proc
class which actually returns a lambda if all the
parameters are not fulfilled. So in this particular case,
I needed three parameters, X, Y, and Z, and
in the first statement, I passed only one. Note,
the invocation is in square brackets. It's different. And
it returns me a lambda, but other times when
all the parameters are actually fulfilled in the second
statement, it actually evaluates the proc. Now if you
had to write the same code you would have
taken different types of input, weighted for the user
with (00:14:18:29) ...?? one, two, three, and evaluated it.
You don't need to do that. And these things
can actually be very helpful. So curry away. So!
So you think you can tell protected from private.
OK, I am not a - I'm a better
programmer than a singer. Right. Private methods. All of
us have been taught since school, unfortunately, that private
methods are not inherited. Are they inherited? As you
can see, foo is a private method. And I
ran out of creativity, so I just went to
the standard base type foo, blah blah blah here.
Is this going to work? All of us take
a lot of things for granted. How many of
you all knew this already, that private methods are
inherited in Ruby? All right, OK, now I'm scared.
How many of you all didn't know this? Don't
be shy, don't be shy. OK, so this is
actually one of the basic principles of where Ruby
actually breaks traditional object oriented concepts. All private methods
are inherited. What? How many of you all have
seen this code before? Forget the Mongoid::Document but include?
Wait, come on. Everybody knows it! What is include?
Is it a keyword? How many thought it was
a keyword? Oh it's like that, require or that
import in Java. Include is a private instance method
defined in the class module. So while that is
sinking in, it raises a basic question. All private
methods are inherited. So what are protected methods? So
what about protected methods? So what's the difference between
private methods and protected methods now? We were told
in our school that protected methods are inherited but
not publicly accessible, right. Now private methods are inherited
but not publicly accessible, right? So what are private
metho- protected methods? Contrary to popular belief, in Ruby
protected methods actually work with objects and not classes.
And you can invoke a protected method on another
object within the same lineage. And I say, what
the... what? Better explained with an example. Simple example,
for the sake of brevity I put the initializer
in one line. What is the output, people? Don't
be shy. You have bumblebee to help you out.
No takers. Come on man, that's like pretty obvious
right. You can't call a protected method on an
object, right? Simple stuff. However. Now beginners, so-called beginners
can tune out. This is fun. I added a
method called fights. Same piece of code. What is
the output? Take a wild guess, man. Go for
it. So either Megatron or Decepticon. Any other deceptive
ideas? Guys, very practically, a quick lesson in human
psychology. If that didn't work, would I have that
slide up there again? It works, man. It works.
But why did it work and how did it
work? The interesting part is that piece of line,
earlier in the previous slide, prime dot nick did
not work, but here target dot nick actually works.
I have called a protected method on an object.
Now that same lineage means that because I'm inside
the class Autobot, because I'm calling a method on
the prime object, which is in, which is in
Autobot class, and since another object called Megatron there
is of the same lineage, it's also an Autobot.
I can call the protected methods. So why didn't
it work earlier? Because everything in Ruby is an
object. If you're trying to start prime dot nick
and the previous case was outside the scope. So
it was effectively in some main class, not the
same lineage, so it doesn't work. So Ruby actually
works in the traditional way, but has different internal
meanings. And if now this was getting a little
complicated, how many of you all thought there are
keywords in Ruby? Cause that man there is gonna
come and shoot you if you think Ruby has
keywords. Does that code work? Is it even valid?
Should it give me a syntax error? If, how
many of you think it will give me an
error? Syntax error too? What's wrong with you? Have
you gone mad?-kind of errors. Any takers for syntax
errors? Probably not. But if not, then I want
to ask you know what is the output of
this code? Seriously. There it is, seriously. Question is,
how many of you all thought this is an
error called stack_too_deep. Cause when I call false it
calls true, once you call true it will call
false. And it goes into a recursive loop and
case stack_too_deep. Any takers for stack_too_deep? Higher, higher! And
how many think it will actually work? All right.
The rest of the people, you all are beginners.
But yeah this works. So it does not stack_too_deep.
This actually works because true, true's resolution is immediately
determined as the boolean value. However if I had
changed these two particular statements, the content in the
methods to self dot false and self dot true
I would probably get stack_too_deep. Not probably, definitely get
stack_too_deep. OK. So. If this wasn't complex enough for
you, let's go to modules, the mysterious modules. You
know what the bull I have with my good
friend module, which has power, Megatron is super powerful,
and he's a force, he's evil. And I want
to put that in my class Hanuman. note the
star, because that's true. I want the power of
Megatron with Hanuman. Hanuman! Unfortunately this will not go
down too well religiously for us, because though it
will be Hanuman will be as powerful as Megatron,
Hanuman is now evil! So what do I do?
Is there a way I can cherry-pick from Megatron,
saying, I want the power of Megatron but I
don't want to be evil? What do I do?
I require. Note, I have not included Megatron, I
require the Megatron method- Megatron file, Megatron RB. I
define a method called power and I go to
the module, tell him to give me that instance
method called power, which gives me something called an
unbounded method. And then I bind it to me,
that is self, and I call it. And that
makes my Hanuman religiously acceptable to society. Question? No.
So note self, self is the object call. So
it's not working on the class call, it's actually
working on the instance. So every object, every instance
of Hanuman, will actually get the power of Megatron.
And with that I end my talk and thank
my two assistants here. I have, I'm open for
a few questions. Do I have the time, guys?
Satish, do I have some time? For questions? Yay!
We have a lot of time for questions! All
right, you. Thank you. You have a question there.
QUESTION: What exactly lead you to title this talk
as the Dark Side of Ruby? G.R.: Oooh. Now
he killed me, didn't he? So that was a,
there's a two-sided answer to that. One was to
fool the organizers, to get the CF?? (00:23:05:23) accepted.
But more importantly, the dark side of Ruby tries
to bring out the weirdness in Ruby, which is
not the evil part, but the hidden part. Like
the dark side of the moon where we have
all these kind of stuff that breaks, the gotchas,
the moment that we feel that are going to
help but you don't really need to care about
it, but it's really, really important that you know
these things exist. That's why Dark Side of Ruby.
So I still love Ruby - no offense. Any
other questions? Yes sir. QUESTION: So have you suffered
because of any of these gotchas in you work?
G.R.: Absolutely! This is all part of experience. Part
(00:23:53:00 ??) is part of experience, part is training,
and partly is preparation for my talk, trying to
find out these terms, and figuring things out. There's
a lot of stuff that I've actually kept out,
like you know ?? (00:24:07:03) games. Lots of fun
with method missing. I haven't even touched upon blocks
and ?? There's lots of funny stuff which happens
there. But I have only half an hour. So
the question to you guys also is that in
case you find some of these funny things which
happen in Ruby, and are able to explain it
or not able to explain it, send me a
Tweet, send me an email, and I will probably
investigate and improve my talk at your expense. QUESTION:
Yeah. So the other question is, are there some
practices, certain things that I follow, so that I
don't get, I don't encounter these? G.R.: Well, so
one thing, these aren't problems. What I wanted to
point out here is that this is not a
bad part of Ruby, but these are the things
that we take for granted. So knowing about protected
and private being different is important. But not mandatory
for us to work as Rails programmers. But if
you know that, how protected and private actually work,
it makes us better programmers. So best practices of
Ruby are already there. You know there are things
like flip-flops in Ruby which is for lack of
a better term, a mind star star star star.
But, I do not recommend it. But it's there.
There are plenty of other things in Ruby, too.
Which work, which should work, which you should use.
The bottom line is that Ruby gives us the
maximum flexibility to build the way we want to
build our code. So with great power comes great
responsibility. And sometimes it's irresponsible. So it worked out
great. Yeah. QUESTION: So is there a good parts
of Ruby, like good parts of Java- G.R.: What?
QUESTION: Good parts of Ruby? G.R.: Oh, good parts?
Everything! I've been working in Ruby for six years
and I still love it. QUESTION: No, there is
a famous book called Good Parts of JavaScript, a
very thin book that allows a subset of language
that is very safe to use, that you can
be very productive in. So do you, have you
come across something that says, like, there's a subset
that you should stick to and use? G.R.: So
the best part about Ruby that I like is
the closures, which is completely misunderstood, because every time
I talk to any person who's getting into Ruby
and I show them what a closure is they're
like yeah, that's a loop. But it's not. It's
like far more better than that. And it's far
more - it's more intuitive. It gets into the
details and gives us so much more incentive about
learning how Ruby internals work, that we tend to
actually ignore it in Rails. And I only (00:26:30:29)
have a lot of respect for people who have
learned Ruby and gone to Rails, because they know
the right thing, other than most of us, including
me, who got into Rails and then fell in
love with Ruby. So it's different. QUESTION: So is
Ruby the good parts the next book? G.R.: Could
be. But I'll need a lot of community support
for that. Yes? QUESTION: Yeah, hi, thanks for the
talk. Just (00:26:55:09). I have been checking out Exorcism
dot IO. I don't know if you guys have
heard of it. So it's actually started by Katrina,
who's part of the Ruby Rogues, and I have
had a wonderful time running stuff from Ruby, like
I have been working Ruby for ?? (00:27:08:20) for
years and also gotchas- G.R.: So, Exorcism dot IO.
That's great. QUESTION: Like really good Ruby idioms that
like so it's basically what happens is you, there
are around ten languages if I'm not wrong. You
can pick Ruby, you can sub in your solutions.
People can look at your code. They can give
good reviews. You can help out others with your
suggestions. Yeah- G.R.: But to add to that, there
is also some interesting - I'm not sure if
you all have heard of Winbgall (00:27:33:08). Wingolf was
a gem and a simple tool where you can
report a problem statement, and using whim, you know
execute that in the least number of key presses.
Similarly there are a few initiatives for Ruby golf,
where you can actually try things like, the beginner
?? they actually said they have things with ??
you know stuff like, write this piece of code
without using arrays, or without using the equality operator.
And then you start, your mind starts churning, and
then you dig deeper into Ruby and find other
things. So the best way to find these things
is to try Ruby ?? All right we had
a question there too. QUESTION: Not really a question,
but just a suggestion, actually, to folks who are
trying to learn Ruby. I like that he pointed
out that some of the things that we've learned
in college, classical logic and stuff doesn't really apply.
What really helped me understand differences was that treat
Ruby as a object-focused language and most of the
languages that you probably end up working with, Java,
C sharp, they'll be class focused. So concepts like
private, protected, just like you mentioned, are all object-level
concepts in Ruby. In fact if you wanted to
draw parallels again JavaScript is a good parallel because
JavaScript is also an object-focused language. So there are a
lot of parallels between JavaScript and Ruby, and
less between Java and Ruby.
QUERANT: Yeah, and-
It's like the dot, I'm sorry, that dot thing just amazed me.
??, just having a dot.
and I was actually kind of disappointed when it
ended. I just wanted more. OK.
G.R.: Cool. Thank you.
Yes?
The Well-Grounded Rubyist. A must read.
V.O.: Somebody Tweet about it, please.
V.O.: We'll take one last question.
QUERANT: How does it help to have protected and private method
different from other languages? The way Ruby does it?
G.R.: I'm sorry. Did you ask what is different between protected and private-
QUERANT: No. How does it help to have a different design implementation,
to have it different.
G.R.: Oh. Excellent. And I love answering this question.
Though sometimes it can be a little long.
Why is private and protected different private and protected different in Ruby than
in other traditional standard languages?
Because Ruby did it right.
That's how it's supposed to be.
Example.
You know, when we talk about object-oriented programming,
it's supposed to be about objects. Things that you can see and touch.
For example: Inheritance.
Right. What is inheritance?
In, put it in, no uncertain term, though, it's my
??
Right. My inherited land my from my ancestors.
It's private. It's inherited.
You can. It, it comes within the family.
It can be protected. Can be private.
But, if you have your dad's wallet, do you inherit it?
You can choose to use it. You can choose not to use it.
It's just there.
The inheritance of land can be protected because it always stays in the family.
Like, for example, the money in the family is protected.
But that's always dealing with parents and children.
You can't go, your father. Just because you have a father and I have a father
I can't go asking your father for money.
Right. It's immense, how you determine. And of course public is the same everywhere.
So Ruby did it right, because it's, everything's object-centric.
Exactly what Aman said just now. Everything's object centric.
And, traditionally in object-oriented concepts, it started off right
and then it went all across the tangent, where you had this inheritance, and
classes and stuff like that. All the standard
things that I never talk about: incapsulation, abstraction, polymorphism
which seem to be the essence of object-oriented programming but is not.
V.O.: So, a follow-up question.
I have it. So is there a well-known pattern that makes use of, makes good of
private and protected?
We understand why- G.R.: Good qu-
QUERANT: Is it because it
G.R.: Include. Include. Include is an excellent example.
There are actually other patterns, too.
There are other patterns which allow for protected, protected is used very heavily for
all sorts of, the usually standard, why use protected, for example
protecting your password generation algorithm.
Something like that. But that's the deal with objects.
And since objects can be called only from their own lineage
you're always safe. Good question.
All right. V.O.: Anymore questions?
If there's anymore questions, we'll take it offline.
G.R.: Sure. Thank you so much
V.O.: Thanks Gautam.