Extract version number from the source

"requiring version.rb" strategy has some issues.

- cannot work when cross-compiling
- often introduces wrong namespace
- must know the superclasses
- costs at each runtime than at build-time

etc.

lib/net/http.rb

@@ -388,6 +388,7 @@ class HTTPHeaderSyntaxError < StandardError; end
   class HTTP < Protocol
 
     # :stopdoc:
+    VERSION = "0.1.0"
     Revision = %q$Revision$.split[1]
     HTTPVersion = '1.1'
     begin

net-http.gemspec

@@ -1,12 +1,15 @@
-begin
-  require_relative "lib/net/http/version"
-rescue LoadError # Fallback to load version file in ruby core repository
-  require_relative "version"
+# frozen_string_literal: true
+
+name = File.basename(__FILE__, ".gemspec")
+version = ["lib", Array.new(name.count("-")+1, "..").join("/")].find do |dir|
+  break File.foreach(File.join(__dir__, dir, "#{name.tr('-', '/')}.rb")) do |line|
+    /^\s*VERSION\s*=\s*"(.*)"/ =~ line and break $1
+  end rescue nil
 end
 
 Gem::Specification.new do |spec|
-  spec.name          = "net-http"
-  spec.version       = Net::Http::VERSION
+  spec.name          = name
+  spec.version       = version
   spec.authors       = ["NARUSE, Yui"]
   spec.email         = ["[email protected]"]