Simplify SoftwareSpec checksum methods

Reader methods for specific checksum types have been absent from the
Formula class for some time, so there isn't any reason to expose them in
SoftwareSpec, either.

Thus, these methods now only act as setters, and #checksum should be
used to access the constructed Checksum object.

Library/Homebrew/compat/compatibility.rb

@@ -202,22 +202,15 @@ end
 
 # MD5 support
 class Formula
-  def self.md5(val=nil)
-    unless val.nil?
-      @stable ||= SoftwareSpec.new
-      @stable.md5(val)
-    end
-    return @stable ? @stable.md5 : @md5
+  def self.md5(val)
+    @stable ||= SoftwareSpec.new
+    @stable.md5(val)
   end
 end
 
 class SoftwareSpec
-  def md5(val=nil)
-    if val.nil?
-      @checksum if checksum.nil? or @checksum.hash_type == :md5
-    else
-      @checksum = Checksum.new(:md5, val)
-    end
+  def md5(val)
+    @checksum = Checksum.new(:md5, val)
   end
 end
 

Library/Homebrew/formula.rb

@@ -677,12 +677,9 @@ private
 
     Checksum::TYPES.each do |cksum|
       class_eval <<-EOS, __FILE__, __LINE__ + 1
-        def #{cksum}(val=nil)
-          unless val.nil?
-            @stable ||= SoftwareSpec.new
-            @stable.#{cksum}(val)
-          end
-          return @stable ? @stable.#{cksum} : @#{cksum}
+        def #{cksum}(val)
+          @stable ||= SoftwareSpec.new
+          @stable.#{cksum}(val)
         end
       EOS
     end

Library/Homebrew/formula_support.rb

@@ -33,12 +33,8 @@ class SoftwareSpec
   # The methods that follow are used in the block-form DSL spec methods
   Checksum::TYPES.each do |cksum|
     class_eval <<-EOS, __FILE__, __LINE__ + 1
-      def #{cksum}(val=nil)
-        if val.nil?
-          @checksum if @checksum.nil? or @checksum.hash_type == :#{cksum}
-        else
-          @checksum = Checksum.new(:#{cksum}, val)
-        end
+      def #{cksum}(val)
+        @checksum = Checksum.new(:#{cksum}, val)
       end
     EOS
   end
@@ -94,11 +90,9 @@ class Bottle < SoftwareSpec
   # a Hash, which indicates the platform the checksum applies on.
   Checksum::TYPES.each do |cksum|
     class_eval <<-EOS, __FILE__, __LINE__ + 1
-      def #{cksum}(val=nil)
+      def #{cksum}(val)
         @#{cksum} ||= Hash.new
         case val
-        when nil
-          @#{cksum}[MacOS.cat]
         when Hash
           key, value = val.shift
           @#{cksum}[value] = Checksum.new(:#{cksum}, key)

Library/Homebrew/test/test_formula.rb

@@ -111,10 +111,6 @@ class FormulaTests < Test::Unit::TestCase
     assert_match /[0-9a-fA-F]{40}/, f.stable.checksum.hexdigest
     assert_match /[0-9a-fA-F]{64}/, f.devel.checksum.hexdigest
 
-    assert_nil f.stable.sha256
-    assert_nil f.bottle.sha256
-    assert_nil f.devel.sha1
-
     assert_equal 1, f.stable.mirrors.length
     assert f.bottle.mirrors.empty?
     assert_equal 1, f.devel.mirrors.length