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#------------!WARNING!------------------
#makefiles require an actual tab character for the indenting.
#I use macvim as my text editor, and I have it configured
#to convert tabs to spaces for all file types.  To make sure
#that doesn't happen to a makefile, I added the following to 
# ~/.vimrc:
#
#   au FileType make setlocal noexpandtab tabstop=4 shiftwidth=4 softtabstop=0
#
#---------------------------------------
#
#First the makefile without comments:


modules = aw2 runs index w2

all: $(modules:%=%.beam) 
.PHONY: all

%.beam: %.erl
	erlc -W $< 
	
clean:
	rm $(modules:%=%.beam) erl_crash.dump
.PHONY: clean


#Now, with comments:

#Assign all the modules in your project to a variable:
modules = aw2 runs index w2
#For the week2 assignment, I used some previously defined functions in w2.erl,
#and index.erl was provided for us, then after I wrote the indexing code 
#in aw2.erl, I created a separate module, runs.erl, for the solution
#that prettifies the line numbers.

#The following is the first "target" in this makefile, which
#means that make will try to create the file "all" (and only
#the minimum necessary to creat the file "all) by
#first creating the "prerequisite" files, which are listed to
#the right of the colon after "all".  The syntax used to the right
#of the colon converts the names in the modules variable
#above to names with a .beam extension.  $() is used to
#interpolate variables, and % is a wild card character.
#In this case, 
#     $(modules:%=%.beam) 
#is equivalent to:
#     aw2.beam runs.beam index.beam w2.beam
#
all: $(modules:%=%.beam) 
.PHONY: all

#In order for make to create the file "all",
#make must figure out how to create the prerequisites,
#so make looks further down the makefile to figure
#out how to create the files aw2.beam, runs.beam,
#index.beam, and w2.beam.

#Ah, below is a target which instructs make on how it
#can create any .beam file: make should take the
#correspondingly named .erl file. and apply the 
#"recipe" on the second line to the .erl file to create
#the .beam file.  In the recipe, the .erl file is referred
#to with the variable name:
#           $< 
#It represents the full file name of the file that matched 
#the pattern on the right side of the colon.
#Yep, it's scary looking syntax. Welcome to perl!
#The -W options is for warnings.
%.beam: %.erl
	erlc -W $< 
	
#To execute the "clean" target below, you need to use
#this command:
#
#    $ gmake clean
#
#Because creating the "clean" target is not required
#to create the first target in the file, which is "all" 
#in this makefile, gmake/make skips "clean" when you do:
#
#      $ gmake
#
#To create the "clean" target, you need to specify "clean" 
#when you call gmake/make, then gmake/make tries to create
#only the "clean" target and its prerequisites.  The 
#clean target lacks any prerequisites, so make just
#executes the recipe.

clean:
	rm $(modules:%=%.beam) erl_crash.dump
.PHONY: clean

#Note that both "all" and "clean" are phony targets because
#none of the recipes will actually create a file called "all"
#or "clean" (which means that make really feels like it failed
#you!).  It's considered good practice to declare your phony
#targets with .PHONY: -- for reasons I won't go into.