REVIEW: APIs

Reddit Code-Along

Let's build an app similar to the petitions app we built, now with the reddit API!

Sample Endpoint: http://www.reddit.com/r/funny.json

Documentation: http://www.reddit.com/dev/api

Code Solution: https://github.com/iExperience/reddit

A version control system is a tool to keep track of revisions you make to your files.

Some version control systems, such as Dropbox automatically keep revisions of every file you make.

What if we had some kind of time machine that allowed us to undo mistakes we make?

if student.going_skydiving?
  store_moment :before_jump
end

# ...

if chute.failed? && student.screaming?
  restore_moment :before_jump
end

That's what git allows us to do for code.

Git

Git stores all of your code and each revision of your code in a repository.

Git is a source control manager (SCM), which is like a more powerful and complex Dropbox.

Developer workflow

Other git commands

$ git init # initialize a new Git repo
$ git status # view current state of Git repo
$ git checkout # Undo local, unstaged changes

Deleting files

Deleting a file requires you to use git rm.

If you don't, you can still use git add --all so git can know that you deleted a file.

$ git rm <file> # Delete a file and track it

OR

$ rm <file>
$ git add --all   # Will notice deleted files

WHY IS GIT SO COMPLEX?!

Git Summary

PROS

• Save your code's history so you can take risks
• Store, track, undo, redo revisions of your code

CONS

• Really dang confusing and challenging to use
• "Why am I doing this?" takes a while to overcome

GitHub

Backs up your local git repository on the cloud.

• view your code's history visually
• pull requests
• plus a lot of other useful features

Instructor Demo

Let's push some local projects onto GitHub!

Merge Conflicts

Uh oh! Two people changed the same code.

<<<<<<<< HEAD
  # this is my latest change
  hobbit = Ringbearer.new(50, "Bilbo")
========
  # this is the conflicted (existing) change
  hobbit = Ringbearer.new(35, "Frodo")
>>>>>>>> Updated ringbearer to reflect modern history

Fixing merge conflicts is called resolving.

What does it mean if my changes were 'rejected'?

$ git push

To https://github.com/iExperience/iExperience.github.io.git
 ! [rejected]        master -> master (fetch first)
error: failed to push some refs to 'https://github.com/iExperience/iExperience.github.io.git'
Updates were rejected because the remote contains work
that you do not have locally. This is usually caused by another
repository pushing to the same ref. You may want to first integrate
the remote changes (e.g., 'git pull ...') before pushing again.

Someone else has made changes to the remote repository that you don't have yet.

$ git fetch
$ git merge

RECAP

• Local repository and an optional remote repository
• Working copy -> staging -> local repository
• . means current directory
• Github stores your code in the Cloud, plus cool features!
• Merge conflicts happen
• Don't forget to fetch and merge before pushing!

EXERCISES

http://iexperience.github.io/year02/sA/exercises/5A.html