Why use a Version Control System?

Overview

Teaching: 10 min
Exercises: 0 min
Questions
  • What is version control software?

  • Why should I use it?

Objectives
  • Explain what version control software does

  • Describe the advantages of using version control

  • State that Git is an example of version control softwares

The Essence of Version Control


What Can Go Wrong Without Version Control

Consider the following directory listing. This is a common situation that can occur when working without version control (in fact it’s probably the best case scenario).

mylib-1.2.4_18.3.07.tgz         somecode_CP_10.8.07.tgz
mylib-1.2.4_27.7.07.tgz         somecode_CP_17.5.07.tgz
mylib-1.2.4_29.4.08.tgz         somecode_CP_23.8.07_final.tgz
mylib-1.2.4_6.10.07.tgz         somecode_CP_24.5.07.tgz
mylib-1.2.5_23.4.08.tgz         somecode_CP_25.5.07.tgz
mylib-1.2.5_25.5.07.tgz         somecode_CP_29.5.07.tgz
mylib-1.2.5_6.6.07.tgz          somecode_CP_30.5.07.tgz
mylib-1.2.5_bexc.tgz            somecode_CP_6.10.07.tgz
mylib-1.2.5_d0.tgz              somecode_CP_6.6.07.tgz
mylib-1.3.0_4.4.08.tgz          somecode_CP_8.6.07.tgz
mylib-1.3.1_4.4.08.tgz          somecode_KT.tgz
mylib-1.3.2_22.4.08.tgz         somecode_PI1_2007.tgz
mylib-1.3.2_4.4.08.tgz          somecode_PI_2007.tgz
mylib-1.3.2_5.4.08.tgz          somecode_PI2_2007.tgz
mylib-1.3.3_1.5.08.tgz          somecode_PI_CP_18.3.07.tgz
mylib-1.3.3_20.5.08.tgz         somecode_11.5.08.tgz
mylib-1.3.3_tstrm_27.6.08.tgz   somecode_15.4.08.tgz
mylib-1.3.3_wk_10.8.08.tgz      somecode_17.6.09_unfinished.tgz
mylib-1.3.3_wk_11.8.08.tgz      somecode_19.7.09.tgz
mylib-1.3.3_wk_13.8.08.tgz      somecode-20.7.09.tgz
...

The trouble with this way of working:

Mistakes Happen

Without recorded snapshots you cannot:

Working on different things

Collaboration

Reproducibility

What about Dropbox or Google Drive?

Using a system like this solves some but not all of the issues above:

Git - A Version Control System

The materials of this course focus on teaching the version control software (VCS) Git. Whilst there are many different implementations of VCS, Git has become established as by far the most widely used. We focus on use of Git via its command line interface as we believe this is the best way to communicate the important fundamental concepts.

Git is a very powerful tool. Unfortunately it is also quite difficult start using. Git often uses confusing and unintuitive terminology and benefits of its use are often only apparent in the longer term. Today we will make every effort to demystify Git and make clear why it’s usage is an essential part of any programming activity.

These materials are written in the style of The Carpentries. If attending an instance of this workshop you are fully encouraged to “type along” with the instructor in order to be able to complete the exercises.

Key Points

  • Version control software refers to a type of program that records sets of changes made to files

  • VCS is a ubiquitous tool for software development

  • Tracking changes makes it easier to maintain neat and functional code

  • Tracking changes aids scientific reproducibility by providing a mechanism to recreate a particular state of your code base

  • VCS provides a viable mechanism for 100’s of people to work on the same set of files

  • VCS lets you undo mistakes and restore a code base to a previous working state

  • Git is the most widely used version control software

  • Using Git allows access to online tools for publication and collaboration