Add 'build' DSL method.

Disallow processing Environments until configuration is performed.

build_tests/two_sources/Rsconscript

@@ -1,4 +1,6 @@
-Rscons::Environment.new(echo: :command) do |env|
-  env.Object("one.o", "one.c", 'CPPFLAGS' => ['-DONE'])
-  env.Program('two_sources.exe', ['one.o', 'two.c'])
+build do
+  Rscons::Environment.new(echo: :command) do |env|
+    env.Object("one.o", "one.c", 'CPPFLAGS' => ['-DONE'])
+    env.Program('two_sources.exe', ['one.o', 'two.c'])
+  end
 end

build_tests/two_sources/assuffix.rb

@@ -1,7 +1,9 @@
-Rscons::Environment.new do |env|
-  env["ASSUFFIX"] = %w[.ssss .sss]
-  env["CFLAGS"] += %w[-S]
-  env.Object("one.ssss", "one.c", "CPPFLAGS" => ["-DONE"])
-  env.Object("two.sss", "two.c")
-  env.Program("two_sources.exe", %w[one.ssss two.sss], "ASFLAGS" => env["ASFLAGS"] + %w[-x assembler])
+build do
+  Rscons::Environment.new do |env|
+    env["ASSUFFIX"] = %w[.ssss .sss]
+    env["CFLAGS"] += %w[-S]
+    env.Object("one.ssss", "one.c", "CPPFLAGS" => ["-DONE"])
+    env.Object("two.sss", "two.c")
+    env.Program("two_sources.exe", %w[one.ssss two.sss], "ASFLAGS" => env["ASFLAGS"] + %w[-x assembler])
+  end
 end

build_tests/two_sources/cache_strict_deps.rb

@@ -10,10 +10,12 @@ class StrictBuilder < Rscons::Builder
   end
 end
 
-Rscons::Environment.new(echo: :command) do |env|
-  env.add_builder(StrictBuilder.new)
-  env.Object("one.o", "one.c", "CCFLAGS" => %w[-DONE])
-  env.Object("two.o", "two.c")
-  sources = File.read("sources", mode: "rb").split(" ")
-  env.StrictBuilder("program.exe", sources)
+build do
+  Rscons::Environment.new(echo: :command) do |env|
+    env.add_builder(StrictBuilder.new)
+    env.Object("one.o", "one.c", "CCFLAGS" => %w[-DONE])
+    env.Object("two.o", "two.c")
+    sources = File.read("sources", mode: "rb").split(" ")
+    env.StrictBuilder("program.exe", sources)
+  end
 end

build_tests/two_sources/libsuffix.rb

@@ -1,6 +1,8 @@
-Rscons::Environment.new() do |env|
-  env["LIBSUFFIX"] = %w[.aaaa .aaa]
-  env.Library("one.aaaa", "one.c", "CPPFLAGS" => ["-DONE"])
-  env.Library("two.aaa", "two.c")
-  env.Program("two_sources.exe", %w[one.aaaa two.aaa])
+build do
+  Rscons::Environment.new() do |env|
+    env["LIBSUFFIX"] = %w[.aaaa .aaa]
+    env.Library("one.aaaa", "one.c", "CPPFLAGS" => ["-DONE"])
+    env.Library("two.aaa", "two.c")
+    env.Program("two_sources.exe", %w[one.aaaa two.aaa])
+  end
 end

build_tests/two_sources/objsuffix.rb

@@ -1,6 +1,8 @@
-Rscons::Environment.new do |env|
-  env["OBJSUFFIX"] = %w[.oooo .ooo]
-  env.Object("one.oooo", "one.c", "CPPFLAGS" => ["-DONE"])
-  env.Object("two.ooo", "two.c")
-  env.Program("two_sources.exe", %w[one.oooo two.ooo])
+build do
+  Rscons::Environment.new do |env|
+    env["OBJSUFFIX"] = %w[.oooo .ooo]
+    env.Object("one.oooo", "one.c", "CPPFLAGS" => ["-DONE"])
+    env.Object("two.ooo", "two.c")
+    env.Program("two_sources.exe", %w[one.oooo two.ooo])
+  end
 end