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.

2 files changed, 10 insertions, 8 deletions

diff --git a/lib/weakref/version.rb b/lib/weakref/version.rb
deleted file mode 100644
index 893da80753..0000000000
--- a/lib/weakref/version.rb
+++ /dev/null
@@ -1,3 +0,0 @@
-module Weakref
-  VERSION = "0.1.0"
-end
diff --git a/lib/weakref/weakref.gemspec b/lib/weakref/weakref.gemspec
index 886ae13d9f..a7c83a53e7 100644
--- a/lib/weakref/weakref.gemspec
+++ b/lib/weakref/weakref.gemspec
@@ -1,10 +1,15 @@
-lib = File.expand_path("lib", __dir__)
-$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
-require "weakref/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          = "weakref"
-  spec.version       = Weakref::VERSION
+  spec.name          = name
+  spec.version       = version
   spec.authors = ["Yukihiro Matsumoto"]
   spec.email = ["matz@ruby-lang.org"]