An Introduction To Software Development

Using Python

Spring Semester, 2014

Class #11:Build Scripts

Homework #1 Was Really A Bunch Of Parts

Put Together

Get Inputs

CalculateAge

Encrypt SS

Number Collect Older / Younger

Information

PrintFull

Name

PrintStreet

Address PrintGender

Print Flipped

DOBAndAge

Print Insurance

Status

Print 2 Versions

Of SS Number

Print MedicaidNumber

Print Parent’sName

Software Must Be Usable

• When a new developer joins your team, will he/she know what dependencies to worry about? Or what code is needed to test things?

• Many things can be done with your code:– Compile all of it– Run part of it– Package up– Etc.

• A version control system will do you no good if you can’t be sure that your code will be used correctly once it’s been checked out

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Good code needs to be easy to use in addition to being easy to get

Say Hello To “Build Scripts”

• In order to run a software project, more than just compiling of code must be done.

• The project must be “built”.

• Building a project involves the following steps:– Compiling source files into binary files– Finding dependencies– Packaging up the project– Etc.

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What Dependencies Did We Have In Homework

#1?

Get Inputs

CalculateAge

Encrypt SS

Number Collect Older / Younger

Information

PrintFull

Name

PrintStreet

Address PrintGender

Print Flipped

DOBAndAge

Print Insurance

Status

Print 2 Versions

Of SS Number

Print MedicaidNumber

Print Parent’sName

How To Build A Project

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Since the same steps are performed each time, building a projectIs the prefect candidate for automation using a tool.

Say Hello To Ant

• Apache Ant is a build tool for Java thatcan compile code, create and deletedirectories and even package files for you.

• Ant uses a build script to accomplish all of this

• Build scripts are written in XML

• Build scripts tell Ant what to do when you need to build your program.

Image Credit: en.wikipedia.org

How It All Works

• In Ant, each build file represents a single project

• The file is called a build script

• The file, called build.xml, contains the steps need to build your project

• What is needed to build your project is broken up into steps that are called targets

• Each target can have more than one task

• To build a project, you just run Ant with your build file

Image Credit: www.fg-a.com

Projects, Properties, Targets, and Tasks• Projects: Everything in your build file is part of a single project:

<project name=“Homework 1” default =“dist”>

• Properties: Ant properties are like constants for the script. They let you refer to values in the script; however, you can change those values in a single place.<property name=“version” value=“1.0” />

• Targets: A target is just a set of work. You can group different actions into a target. Example: You might have an init target for setting up your project’s directory structure and a compile target for compiling all of your code. A target has a name and, optionally, a list of targets that must be run before it.<target name=“compile” depends=“init” description=“Compiles code”>

• Tasks: A task in Ant generally maps to a specific command<mkdir dir=“/homework_1” >

No matter what language you are using, a good build tool gives youa way to manage projects, constants, and specific tasks.

Image Credit: www.clipartpanda.com

What A Pain! Why Bother With A Build

Tool?• A build tool, like Ant, lets you get things done faster –

especially when you are working on multiple projects.

• The build tool is really for the team – not just you!

• The tool allows everyone on the team to turn source code into a running application.

• A build script makes it impossible for a developer to leave a step out.

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What Makes A Good Build Script?

• A good build script captures details that the developers don’t have to worry about.

• The description information included in tags in the build file can be used to automatically generate documentation.

• Build scripts compile the code in your project. Ant can handle target dependencies: init depends on compile which depends on dist

• You should always have a target that cleans things up: delete the directories created during compiling

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A Good Build Script Does More…

• Add required libraries– If your application depends on libraries that you don’t want to store

locally, you can have Ant download during the build process

• Run the application– Does your application require a complex library path?– Does it need a long string of command line options?

• Generate documentation– Ant can display documentation from the build file

• Check out code, run tests, create archives, encrypt files, email you when the build is done

Automation allows you to keep your focus on your code,not on repetitive tasks…

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What To Do With The Build Script…?

• It turns out that your build script is code also!

• This code belongs in a repository

• You should always check your build script code into your code repository

• Now it’s available to everyone when they do an update

• Version control software tracks all changes

• Script gets tagged when you do a release

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What We Covered Today

1. Build scripts

2. Projects

3. Properties

4. Targets

Image Credit: http://www.tswdj.com/blog/2011/05/17/the-grooms-checklist/

What We’ll Be Covering Next Time

1. Testing

2. Continuous integration

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