workshops/slides/makefiles/makefiles.md

title, author, theme, colortheme

title	author	theme	colortheme
Making Makefiles	Malin	Warsaw	orchid

Intro

The fundamental problem:

git submodule update --init soundscape
cargo build --release
install -pm755 target/release/tap /usr/local/bin/

You can't type this after every test.

---

First Solution

#!/bin/sh
git submodule update --init soundscape
cargo build --release
install -pm755 target/release/tap /usr/local/bin/

At this point, every test takes 10 minutes.

Second Solution

#!/bin/sh
[ -f soundscape/.git ] || git submodule update --init soundscape
[ -f target/release/tap ] || cargo build --release
[ -f target/release/tap ] || \
    install -pm755 target/release/tap /usr/local/bin/

---

Makefile Solutions

• input, process, output.
• automatic idempotence

INSTALL_DIR = /usr/local/bin

soundscape/.git:
    git submodule update --init soundscape

/usr/local/bin/tap: target/release/tap
	install -pm755 target/release/tap $(INSTALL_DIR)

target/release/tap: src soundscape/.git
	cargo build --release

---

Basic

• Gotcha: directories
• This, that, and these

---

Repetition, Repetition, Repetition

.PHONY: output
output: release/index.html

release/: backups.zip
	mkdir $@

release/index.html: index.html release/
	cp  $< $@

index.html: backups.zip
	unzip $<

---

Variables

• From your shell.
• New variables.
• Filenames as variables.
• Gotcha: no shell variables, only make!

Equality

• Variables with '=', never ':='.
• Gotcha: one shell per line.
• Variables as shell output.

---

Phonies, and the Problems with Lies

• clean (common)
• check (excellent)

---

Non-Compiling Checks

• make -n
• Gotcha: shell output variables.

---

The Fourth Sigil: %

• Standard rules, e.g. ImageMagick, copying, et c.
• Gotcha: intermediaries are deleted.

---

Bling: make2graph

• Gotcha: completely outdated.

---

Inclusivity

• include dir/Makefile
• Gotcha: directory has not changed
• $(MAKEFILE_LIST)

Special Commands

• dir
• DIR = test -d $(dir $@) || mkdir $(dir $@)
• patsubst
• Wildcards (or not?)

Maintanance

• backups
• saving files