From: Joe Van Dyk <joevandyk@...>
Date: 2005-07-15T16:06:32+09:00
Subject: Re: rake question

On 7/14/05, Joe Van Dyk <joevandyk@gmail.com> wrote:
> rule '.o' => ['.c'] do |t|
>     sh "cc #{t.source} -c -o #{t.name}"
> end
> 
> But, when I change the .c source file, it doesn't get compiled again.
> Why is that?
> 
> Example:
> 
> PowerBook:~/that_stuff/test1 joe$ ls
> Rakefile                another_test.h          test.cpp
> another_test.cpp        main.cpp                test.h
> 
> PowerBook:~/that_stuff/test1 joe$ cat Rakefile
> require 'rake/clean'
> CLEAN.include '*.o', 'test'
> CPP_SOURCE = FileList['*.cpp']
> OBJS = CPP_SOURCE.ext 'o'
> 
> task :default => :run
> task :run => "test" do
>   sh "./test"
> end
> file "test" => OBJS do
>   sh "g++ -o test #{OBJS}"
> end
> rule '.o' => '.cpp' do |t|
>   sh "g++ -c -o #{t.name} #{t.source}"
> end
> CPP_SOURCE.each do |cpp|
>   headers = File.read(cpp).scan(/^#include "(.+)"/)
>   task cpp => headers
> end
> 
> PowerBook:~/that_stuff/test1 joe$ rake
> (in /Users/joe/that_stuff/test1)
> g++ -c -o another_test.o another_test.cpp
> g++ -c -o main.o main.cpp
> g++ -c -o test.o test.cpp
> g++ -o test another_test.o main.o test.o
> ./test
> Whassup
> what's up!
> 
> 
> PowerBook:~/that_stuff/test1 joe$ touch main.cpp
> PowerBook:~/that_stuff/test1 joe$ rake
> (in /Users/joe/that_stuff/test1)
> ./test
> Whassup
> what's up!
> 
> It should've recompiled main.cpp and relinked everything, right?

When I comment out 
> CPP_SOURCE.each do |cpp|
>   headers = File.read(cpp).scan(/^#include "(.+)"/)
>   task cpp => headers
> end

Then it works as expected.  So, "task cpp => headers" is the culprit. 
But I'm still not sure why it breaks everything else.