dependency ladder example

slides/makefiles/dependency_ladder/.gitignore

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+*

slides/makefiles/dependency_ladder/makes/books

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+MONTHS != date +%B && date -d '1 month' +%B
+IP != dig +short myip.opendns.com @resolver1.opendns.com
+CITY != curl -s http://api.db-ip.com/v2/free/$(IP) | grep city | cut -d: -f2 | tr -d '"'
+
+TITLES = $(MONTHS)
+TITLES += $(CITY)
+
+BOOKS = $(patsubst %,Books/%.md,$(TITLES))
+
+$(BOOKS):
+	@mkdir -p $(@D)
+	fortune -l > $@
+
+progs += $(BOOKS)
+
+dross += Books/

slides/makefiles/dependency_ladder/makes/cows

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+cows = $(patsubst Forts/fortune_%.md,Cows/cow-%.txt,$(wildcard Forts/fortune_*.md))
+
+$(cows): Cows/cow-%.txt: Forts/fortune_%.md
+	@mkdir -p $(@D)
+	cat $< | cowsay > $@
+
+progs += forts
+progs += $(cows)
+dross += Cows/
+

slides/makefiles/dependency_ladder/makes/forts

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+
+fnums != seq 8 | sort -R | head -2
+forts = $(patsubst %,Forts/fortune_%.md,$(fnums))
+
+$(forts):
+	@mkdir -p $(@D)
+	fortune -s > $@
+
+progs += $(forts)
+
+dross += Forts/

slides/makefiles/dependency_ladder/makes/zoo

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+filter = $(shell cowsay -l | sort -R | head -1)
+
+zoo = $(patsubst Forts/fortune_%.md,Zoo/animal-%.md,$(forts))
+
+$(zoo): Zoo/animal-%.md: Forts/fortune_%.md
+	@mkdir -p $(@D)
+	echo '```' > $@
+	cat $< | cowsay -f $(filter) >> $@
+	echo '```' >> $@
+
+progs += forts
+progs += $(zoo)
+
+dross += Zoo/