Python for Beginners, Part 4: Interactive Shell vs. Script

We will discuss the difference between an interactive python terminal vs. A python script.

In case you missed it, here are the previous parts of the series:

• Python for Beginners, Part 1: How to Download and Install Python
• Python for Beginners, Part 2: Hello World Exercise
• Python for Beginners, Part 3: The Turtle Module

Transcript

00:00 - Okay, in this video,

00:01I'm gonna go over the solution to the previous problem

00:03 that I posed to you, and also,

00:05 we're gonna learn how to write the turtle,

00:07 the entire thing,

00:09 in one go.

00:11 So, the problem that I posed to you is,

00:14 make a square with the turtle.

00:16 Well, in your case,

00:17 let's see how you could do exactly that.

00:21 So, let me find the file where we opened up the turtle.

00:23 Let me close that guy right there.

00:25 Copy this line and paste it right there.

00:29 Okay, my turtle has begun.

00:31 Well, the idea is simple.

00:34 I take this line forward, and go 100.

00:38 Now, since sometimes programmers are lazy,

00:40 I don't want to keep writing this over and over again,

00:42 so one thing I can do to make my life easier

00:45 is go to the line that I want to click on,

00:48 I want to use, basically.

00:50 Go to that line, click my mouse there,

00:52 hit 'enter', it brings that down at the bottom,

00:55 as you can see right here.

00:56 And now I can just hit 'enter'.

00:59 So, you can see my turtle just moved left, okay?

01:02 Now it's facing up.

01:05 Now what I want to do is move it forward again,

01:08 and you can see that it's facing up again,

01:11 er, I'm sorry, it's ...

01:13 It moved up, now I need to make it face left.

01:16 So, how do I do that?

01:17 I go left, make it turn 90 degrees,

01:19 and you can see it turned 90 degrees.

01:22 Now I want it to move 100 again.

01:25 You can see it move forward.

01:27 And 90 degrees, and then 100 once again,

01:31 and I have made the square.

01:34 Now, what I want you to be able to do is,

01:38 make a Python file, which means that,

01:41 remember this thing that we opened up right here,

01:45 where we write all of the code at once?

01:48 So, for example,

01:50 I'm gonna close it,

01:51 I'm gonna show you how to open it again, okay?

01:53 So, I'm gonna close this one,

01:54 and I will simply open it again.

01:56 'New file', or 'Command-N'.

01:59 And I will go and put it to the right side,

02:02 just so I have these side by side,

02:05 and I will say something like 'import turtle'.

02:08 Remember that command.

02:09 If you don't use that command

02:11and you try to do 'turtle',

02:12 your program will be like,

02:14 "What the heck is 'turtle'?"

02:16 So, by doing 'import turtle',

02:18 now it knows what 'turtle' is.

02:20 It's like when you're talking about your friends,

02:24 if you talk about your friend John, right?

02:27 Like, let's say you're talking about your friend John

02:29 to your mom, or to your dad,

02:32 and you're like,

02:33 "Dad, this guy blah blah blah",

02:35 you're dad's gonna be like,

02:36 "Who the heck is John?"

02:37 So, you're gonna be like,

02:38 "Oh, yeah, you remember John from my fifth grade class?"

02:43 And then your dad, if you're talking to him,

02:44 he's gonna say,

02:45 "Oh, okay, I know who you're talking about".

02:47 So, 'import' is basically like,

02:50 hey, Python,

02:51 import that turtle that those coders wrote,

02:54 and now we can use it,

02:55 and Python is like,

02:56 "Oh, that turtle",

02:58 but if you don't have this 'import' command here,

03:01Python's gonna be like,

03:02 "What the heck?

03:03 "What turtle are you talking about?

03:04 "You must be out of your mind."

03:06 Anyways.

03:07 We're gonna import this turtle.

03:09 Alright, so now here's what I want you to do.

03:11 I want you to write a script that makes the turtle

03:14 in one single go, okay?

03:18 And I want you to make that square with the turtle

03:21 straight up in one go.

03:22 For example,

03:23 let's come over here to our script that I've written,

03:26 and if I write stuff here,

03:28 it does things immediately, right?

03:30 As you saw,

03:30 but if I come to my right side over here ...

03:34 Oh, by the way, just one quick note.

03:36 Whatever you do, do not name this file 'turtle.py'.

03:40 You can name it 'turtle_game', or 'game',

03:44 or something else,

03:45 just don't name it turtle,

03:47 because then it confuses this turtle here

03:49 with this file,

03:50 and everything goes all over the place.

03:53 So, don't do that,

03:54 'cause I ended up doing that and it caused lots of problems.

03:58 Alright, so let me just show you what happens

04:00 when I run this file.

04:02 I'll go to 'Run', I'll hit 'Run module',

04:04 and hit 'OK'.

04:06 And you can see that my turtle went

04:08 and did all those things in one go.

04:10 How cool is that?

04:11 So you don't have to sit there, type it all in.

04:13 You can just write it in one go,

04:14 and it'll do that every single time.

04:17 So, I want you to work on that square,

04:19 but before you go and do that,

04:21I just want to show you what this file actually looks like.

04:24 So, if I go to,

04:29 let's say,

04:30 'Documents', and 'Clever Programmer',

04:33 'Practice Exercises',

04:35 and we take a look at this file, 'turtle_game',

04:38 it's just a text file with this code in here, okay?

04:42 That's really it, that's all that's going on in here.

04:45 So, I'm gonna

04:47 leave it here.

04:50 The code that you write for the square,

04:52 I want you to either go to the Youtube place,

04:55 Youtube channel, and post it in the comments,

04:58 or I want you to paste your code right here in the comments

05:01on cleverprogrammer.com, okay?

05:03 I'm gonna take a look at it.

05:05 I will see you in the next video.