Collaborative software development

Source control

• Track history and code versions
• Allow merging and branching
• Git, Subversion, Mercurial, etc.

Git and source control

Version and history tracking systems

Two ways of working

Graphical user interface

• Eclipse, VS Code, Tortoise, etc.
• Great when it works well
• Illusion of this is easy

GitHub and collaboration

Help teams plan and collaborate and organize

GitHub as a CV

Use your GitHub profile to show your work!

Git repository

Everything in one folder

• Your regular files you can edit
• .git folder with old versions etc.
• .gitignore and other special files

Working directory
Files you directly edit

Staging area
Selection to be archived

Local repository
History and versions

Remote repositories
Versions on other computer(s)

Creating repository and adding files (1/2)

Initialize empty repository in current folder

1: 
2: 

$ git init
Initialized empty Git repository in C:/Temp/test/.git/

Add new or modified file to the index

1: 
2: 
3: 
4: 

$ git add hello.txt
$ git status
Changes to be committed:
        new file:   hello.txt

Creating repository and adding files (2/2)

Create new version history record (commit)

1: 
2: 
3: 
4: 

$ git commit
[master (root-commit) d70e7d9] Adding hello file
 1 file changed, 1 insertion(+)
 create mode 100644 hello.txt

List the most recent history records

1: 
2: 
3: 
4: 
5: 

$ git log
commit d70e7d97c8598b8c55f01da803447cf95d664504 (HEAD -> master)
Author: Tomas Petricek <tomas@tomasp.net>
Date:   Sat Feb 9 01:36:40 2019 +0000
    Adding hello file

Warning: This slide contains profanities

Git history and branches

Using git for versioning and features

Use branches for different versions and features

Branch is named pointer to a commit

Master branch is typically the "main" once

Branch for each version running in production

Git history and branches (1/3)

Git history and branches (2/3)

Git history and branches (3/3)

Working with branches (1/2)

Create and switch head to a new branch

1: 
2: 
3: 

$ git branch testing
$ git checkout testing
Switched to branch 'testing'

Make a change in a new branch

1: 
2: 
3: 

$ git commit -am "Add experimental features"
[testing 4aaea6a] Add experimental features
 1 file changed, 2 insertions(+), 1 deletion(-)

Working with branches (2/2)

List branches and switch to master

1: 
2: 
3: 

$ git branch -v
* master  d70e7d9 Yadda
  testing 4aaea6a Adding testing

Merge changes from another branch

1: 
2: 
3: 
4: 
5: 
6: 

$ git checkout master
$ git merge testing
Updating d70e7d9..4aaea6a
Fast-forward
 hello.txt | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Git and its alternatives

When is git a wrong tool and alternatives

Uses distributed model with no central server

There are user interface tools for using git

Git is way more complex than it seems

Alternatives include Subversion, Mercurial, Perforce

Source control systems

Software engineering today
From "we know where we want to get"
To "know we continue moving in the right direction"

Using git for version and history tracking
Working dir, staging area, local and remote repositories
Creating, commits, working with branches, merging

CO886: Source control systems

What you should remember from this lecture

• How git stores versions and branches
• Git commit, branch, checkout, pull, push

Tomas Petricek
t.petricek@kent.ac.uk | @tomaspetricek