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Input and Coding Style
6:11Let's explore how to take input from users of our programs
So far, what we have done is all output.
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We printed the screen,
it's not very interactive, is it?
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The conversation's kind of one sided.
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Take a second and
think about applications that you use.
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Just about every one of them gathers
information from you, whether that be
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a field, or a check box, a button click,
or telling a bird when to flap its wings.
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Every application you make is going to
need to gather some information from its
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users, this is called input.
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And gathering input from users from the
command line is pretty straight forward,
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so let's get to it.
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So let's explore this input thing
a little bit in the Python shell first.
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So I'm gonna open that up,
we'll type python.
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Let's give ourselves
a little bit of space.
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All right, so the command to get input
from the user is super easy to remember,
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it's input.
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So input, that's a function,
so we're gonna call it.
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And inside here you put the prompt.
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So let's ask a question, so
let's say, How are you today?
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So see how the cursor is here,
it's waiting for me to type, so how am I?
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Great, I mean you're standing a little
close to me, but pretty great.
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Already we're seeing the importance
of user experience right?
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That prompt made me feel uncomfortable.
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So I'm gonna press Enter.
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And now, remember,
in the REPL we see the results show up.
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So what happens is when you call the input
function, it outputs out the prompt and
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then it waits for an answer.
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Once the answer to the prompt is given,
and
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the user presses Enter,
the result is returned.
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So we know that this input
returns a string, so
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let's capture it in a new variable.
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So let's see,
what would how are you today be?
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[SOUND] I guess that'd probably be
something like current mood, right?
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[LAUGH] Naming things is hard, isn't it?
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So we do current,
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and then we're gonna use the underscore,
cuz there's two words, right?
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So current_mood,
that's current mood in snake case.
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And we'll say, again,
we do the input, How are you today?
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Now, you know what, I'm gonna use couple
of spaces just to give some room there for
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user experience.
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So let's do this.
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So how are you today?
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Well, I am wonderful, especially
[LAUGH] now that you're not standing so
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close to me.
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And now our variable, current_mode,
if we just type that out here,
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we can see what's in it, wonderful.
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Awesome, so you know what,
we could just put this in our program.
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We could ask for
the user's first name, so let's do it.
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So we'll just replace this
value with the input statement.
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We'll say, what is your first name?
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And then we'll definitely
give them some space,
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cuz we want them to feel comfortable,
awesome.
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So now, you know what else,
let's scroll this down,
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let's get rid of these other lines
in here where we're saying hello.
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So I'm gonna Cmd+Shift+D that and
Cmd+Shift+D this,
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and let's bring this back up.
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There we go, that's looking good.
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And it's saved, so let's go ahead,
I'm gonna drop out of the shell, Ctrl+D.
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I'm gonna clear the console, and
I'm gonna type python hello.py.
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So what is your first name?
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I just got an email from one of my
students, so he's on my mind right now.
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So I'll enter Kehinde.
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Hello, Kehinde,
Kehinde is learning Python.
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How's the weather in Nigeria
this time of year, Kehinde?
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And so you'll see that the first
name variable is now set to
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whatever we enter from input.
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So the program changes based on our
user's input, which is awesome.
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Because now we're dealing with input and
output, the staples of application
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development, great job.
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We stumbled right into a fundamental
problem that you're gonna encounter daily
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in your coding journey,
naming things is hard.
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Now you'll get better at it,
[LAUGH] but it's never easy.
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And I can't stress this enough,
a good name is really important.
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You wanna be able to look at your code and
understand and remember what it's doing.
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You wanna be able to read it next week.
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Now one thing to remember, and most people
who are just getting started coding
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don't think about this too often,
other people are going to read your code.
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Now, that might seem like a totally
foreign idea, but ready for this?
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You're going to be most likely on a team,
and
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your teammates will need to understand
what you are trying to communicate.
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We already know that
the computer has rules for
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understanding what we're talking about,
right?
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That's called syntax.
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But what we're talking
about here is coding style.
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[SOUND] There is absolutely nothing
stopping you from using a single letter
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variable name for
the current mood code that we wrote.
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Like I could store the result from
the prompt, how are you today,
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in a variable called m.
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But, I can guarantee that your actual
real life mood is going to change for
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the worst, when you read this code and
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have to try to figure out,
what does m mean?
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Great news though, the Python community as
a whole are very big on consistent style.
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Chances are after you
learn the style rules,
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your code will be indistinguishable
from that of a long time Python coder.
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I'll point these standard style
decisions out as we encounter them.
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The one we've seen already is use
snake_case for variable names.
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Now it's definitely not a syntax error,
you could use another casing system,
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like for instance,
you could say currentMood.
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This is called camel case,
each word here has a new hump.
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[SOUND]
thisIsAnExampleOfWhatCamelCasingLooksLike.
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If you're working with a team on
a project, you'll wanna make sure that you
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follow the same style that is
being used in the project.
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Try to stay consistent.
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So, how are you feeling?
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You've picked up quite a bit
of information over these
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past couple of videos.
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I know that it's a lot,
especially if this is your first language.
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So let me say again,
great job sticking with it.
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What you've been learning will give you
a great foundation to dive deeper and
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explore the language.
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We've got the starts of what every
application has, input and output.
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Next up, let's start processing
that input that we receive,
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right after this quick break.
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