Overview

Teaching: 15 min
Exercises: 15 min

Questions

• What are the advantages and disadvantages of using tools like Make?

Objectives

• Understand advantages of automated build tools such as Make.

Automated build tools such as Make can help us in a number of ways. They help us to automate repetitive commands and, so, save us time and reduce the risk of us making errors we might make if running these commands manually.

They can also save time by ensuring that automatically-generated artifacts (such as data files or plots) are only recreated when the files that were used to create these have changed in some way.

Through their notion of targets, dependencies and actions they serve as a form of documentation, recording dependencies between code, scripts, tools, configurations, raw data, derived data, plots and papers.

Creating PNGs

Add new rules, update existing rules, and add new macros to:

• Create .png files from .dat files using plotcount.py.
• Add the zip_test.py script as dependency of the results.txt file
• Remove all auto-generated files (.dat, .png, results.txt).

Finally, many Makefiles define a default phony target called all as first target, that will build what the Makefile has been written to build (e.g. in our case, the .png files and the results.txt file). As others may assume your Makefile confirms to convention and supports an all target, add an all target to your Makefile (Hint: this rule has the results.txt file and the .png files as dependencies, but no actions). With that in place, instead of running make results.txt, you should now run make all, or just simply make. By default, make runs the first target it finds in the Makefile, in this case your new all target.

Solution

This Makefile and this config.mk contain a solution to this challenge.

The following figure shows the dependencies involved in building the all target, once we’ve added support for images:

Creating an Archive

Add new rules, update existing rules, and add new macros to:

• Define the name of a directory, zipf_analysis, to hold all our code, data, plots and the Zipf summary table.
• Copy all our code, data, plots and the Zipf summary table to this directory.
• Create an archive, zipf_analysis.tar.gz, of this directory. The bash command tar can be used, as follows:

$ tar -czf zipf_analysis.tar.gz zipf_analysis

• Update all to create zipf_analysis.tar.gz.
• Remove zipf_analysis and zipf_analysis.tar.gz when make clean is called.
• Print the values of any additional variables you have defined when make variables is called.

Solution

This Makefile and this config.mk contain a solution to this challenge.

Archiving the Makefile

Why do we add the Makefile to our archive of code, data, plots and Zipf summary table?

Solution

Our code (wordcount.py, plotcount.py, zipf_test.py) implement the individual parts of our workflow. They allow us to create .dat files from .txt files, .png files from .dat files and results.txt. Our Makefile, however, documents dependencies between our code, raw data, derived data, and plots, as well as implementing our workflow as a whole.

Key Points

• Makefiles save time by automating repetitive work, and save thinking by documenting how to reproduce results.