Flow

Flow is a project I wrote using Cosmopolitan. There are some really nice features in here, especially with the build system.

What makes it interesting?

• The make system I built for it is beautiful.
• Just add source files and compile—no hassle.

How Does the Make System Work?

The makefile dynamically discovers all .c and .cpp files in your source directories, sets up object and dependency rules, and makes the build process really tidy.

Here’s a preview:

# Wildcard matching to figure out where sources are based on the DIRS variable
OBJEXT  := .o
LIBEXT  := a

# Safely expand search paths
DIRS    := $(wildcard ../*/)
SEARCH  := $(foreach dir, $(DIRS), $(dir)*.c $(dir)*.cpp) 
SOURCES := $(wildcard $(SEARCH))

# Use patsubst instead of subst to prevent corrupting folder names containing ".c"
OBJECTS := $(patsubst %.cpp, %$(OBJEXT), $(SOURCES))
OBJECTS := $(patsubst %.cpp, %$(OBJEXT), $(SOURCES))
OBJECTS := $(patsubst %.c, %$(OBJEXT), $(OBJECTS))
DEPENDS := $(patsubst %$(OBJEXT), %.o.d, $(OBJECTS))

OBJECTS := $(OBJECTS) $(OBJECTS_EXTRA)

# If a target is not defined, default to test.com
TARGET  ?= test.com

# Define our clean list
RMLIST  := $(foreach dir, $(DIRS), $(dir)*.o $(dir)*.d) *.d *.o *~ *.elf *.dbg 

.PHONY: all info clean

all: $(TARGET)

CC     := ccache $(FLOW_TOOL_COSMOPOLITAN)/bin/cosmocc
CXX    := ccache $(FLOW_TOOL_COSMOPOLITAN)/bin/cosmoc++

PCFLAGS := -Wno-pointer-to-int-cast -MMD -MP -I../ 
PCPPFLAGS := -MMD -MP -I../ 

$(TARGET): $(OBJECTS) 
\t$(CXX) $(OBJECTS) -o $@

%.o: %.c
\t$(CC) $(PCFLAGS) -c -o $@ $<

%.o: %.cpp
\t$(CXX) $(PCPPFLAGS) -c -o $@ $<

# Use double colon rule for clean so regular makefiles can perform additional cleaning. 
clean::
\t-$(RM) $(RMLIST)

-include $(DEPENDS)

Check out the repository for more details and to see this and other interesting techniques.