Practice The Process

class: middle

# .eight[CSET 160:]
## .eight[Web Development II]

---
class: middle

# Practice The Process

---

# Agenda

1. [ ] [What Process?](#process)
2. [ ] [Command Line Arguments](#args)
3. [ ] [Make cat](#cat)
4. [ ] [Make find](#find)

---
name: process

# What Process?

What you should do when you don't know how to write a piece of code.

---

# Process

1. Write in plain english what the code needs to do either as a paragraph or, even better, a list of tasks.
2. Convert this into a list of comments in the file.
3. Under a comment, write a line of code that accomplishes that task.
4. If the comment is too abstract, break it into smaller chunks until there is a line you know you can code.
5. Run the code to check for errors. Use .eight[print] to see if it worked. Go back to step 3 and repeat until you're done.

---

# What Practice?

We're going to do two exercises to implement programs we already know how to use. Why?

- Review the process on our own.
- Become comfortable with deadlines.

---
count: false

# What Practice?

We're going to do two exercises to implement programs we already know how to use. Why?

- Review the process on our own.
- Become comfortable with deadlines.
- Get familiar with command line arguments.
- Review working with files.

---
name: args

# Command Line Args

.fourteen[Go review Exercises 11 through 15.]

- What does .eight[sys.argv] do again?
- What is annoying about it?
- How do we get the contents of a file?
- How do we write new contents to a file?

---

# Command Line Args

Check out the [argparse module](https://docs.python.org/3/howto/argparse.html)

- Create a parser object from the .eight[ArgumentParser] class
- Use that object to set up rules for positional and optional arguments
- Call a method to get the arguments given by the user
- Create help text automatically from rules
- Print usage errors

---
name: cat

# Make cat

Concatenate and print out files.

```sh
$ cat somefile.txt
$ cat A.txt B.txt C.txt
$ cat A.txt B.txt > D.txt
```

Read the man page to see what it can do and what other options there are.

---

# Make cat

```sh
$ python3 cat.py ...args
```

But here's the catch:

.fourteen[You have 45 minutes to implement as much as you can.]

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# Make cat

So how did you do? Take a few minutes to think about what blocked you from doing more.

---
name: find

# Make find

Search through a directory and print file names that match the arguments.

```sh
$ find . -name "*.txt" -print
```

Read the man page for more details

---

# Make find

Use the man page to create a plan of the options you plan on implementing. Some are easier than others.

- .eight[-name] and .eight[-type] are essential
- then try .eight[-print]
- .eight[-exec] will be one of the harder ones, but doable!

.fourteen[Again, you have 45 minutes.]