Add 'build' DSL method.

Disallow processing Environments until configuration is performed.

build_tests/custom_builder/Rsconscript

@@ -9,8 +9,10 @@ EOF
   end
 end
 
-Rscons::Environment.new do |env|
-  env.add_builder(MySource.new)
-  env.MySource('inc.h', [])
-  env.Program('program.exe', Dir['*.c'])
+build do
+  Rscons::Environment.new do |env|
+    env.add_builder(MySource.new)
+    env.MySource('inc.h', [])
+    env.Program('program.exe', Dir['*.c'])
+  end
 end

build_tests/custom_builder/build_after.rb

@@ -1,10 +1,12 @@
-Rscons::Environment.new do |env|
-  env.Command("inc.c",
-              [],
-              "CMD" => %w[ruby gen.rb ${_TARGET}],
-              "CMD_DESC" => "Generating")
-  env["build_root"] = env.build_root
-  env["inc_c"] = "inc.c"
-  env.build_after("${build_root}/program.o", "${inc_c}")
-  env.Program("program.exe", ["program.c", "inc.c"])
+build do
+  Rscons::Environment.new do |env|
+    env.Command("inc.c",
+                [],
+                "CMD" => %w[ruby gen.rb ${_TARGET}],
+                "CMD_DESC" => "Generating")
+    env["build_root"] = env.build_root
+    env["inc_c"] = "inc.c"
+    env.build_after("${build_root}/program.o", "${inc_c}")
+    env.Program("program.exe", ["program.c", "inc.c"])
+  end
 end

build_tests/custom_builder/cvar_expansion.rb

@@ -9,10 +9,12 @@ EOF
   end
 end
 
-env = Rscons::Environment.new do |env|
-  env["hdr"] = "inc.h"
-  env["src"] = "program.c"
-  env.add_builder(MySource.new)
-  env.MySource('${hdr}')
-  env.Program('program.exe', "${src}")
+build do
+  env = Rscons::Environment.new do |env|
+    env["hdr"] = "inc.h"
+    env["src"] = "program.c"
+    env.add_builder(MySource.new)
+    env.MySource('${hdr}')
+    env.Program('program.exe', "${src}")
+  end
 end

build_tests/custom_builder/cvar_lambda.rb

@@ -9,20 +9,22 @@ EOF
   end
 end
 
-e1 = Rscons::Environment.new do |env|
-  env.add_builder(MySource.new)
-  env["one"] = "5"
-  env[:cfg] = {val: "9"}
-  env["two"] = lambda do |args|
-    args[:env][:cfg][:val]
+build do
+  e1 = Rscons::Environment.new do |env|
+    env.add_builder(MySource.new)
+    env["one"] = "5"
+    env[:cfg] = {val: "9"}
+    env["two"] = lambda do |args|
+      args[:env][:cfg][:val]
+    end
+    env["the_value"] = lambda do |args|
+      "${one}${two}78"
+    end
   end
-  env["the_value"] = lambda do |args|
-    "${one}${two}78"
-  end
-end
 
-e1.clone do |env|
-  env[:cfg][:val] = "6"
-  env.MySource('inc.h', [])
-  env.Program('program.exe', Dir['*.c'])
+  e1.clone do |env|
+    env[:cfg][:val] = "6"
+    env.MySource('inc.h', [])
+    env.Program('program.exe', Dir['*.c'])
+  end
 end

build_tests/custom_builder/multiple_targets.rb

@@ -12,8 +12,10 @@ class CHGen < Rscons::Builder
   end
 end
 
-Rscons::Environment.new do |env|
-  env.add_builder(CHGen.new)
-  env.CHGen("inc.c", ["program.c"])
-  env.Program("program.exe", %w[program.c inc.c])
+build do
+  Rscons::Environment.new do |env|
+    env.add_builder(CHGen.new)
+    env.CHGen("inc.c", ["program.c"])
+    env.Program("program.exe", %w[program.c inc.c])
+  end
 end

build_tests/custom_builder/produces.rb

@@ -1,14 +1,16 @@
-Rscons::Environment.new do |env|
-  env["build_root"] = env.build_root
-  env["inc_h"] = "inc.h"
+build do
+  Rscons::Environment.new do |env|
+    env["build_root"] = env.build_root
+    env["inc_h"] = "inc.h"
 
-  env.Copy("copy_inc.h", "${inc_h}")
-  env.depends("${build_root}/program.o", "${inc_h}")
-  env.Program("program.exe", ["program.c", "inc.c"])
+    env.Copy("copy_inc.h", "${inc_h}")
+    env.depends("${build_root}/program.o", "${inc_h}")
+    env.Program("program.exe", ["program.c", "inc.c"])
 
-  env.Command("inc.c",
-              [],
-              "CMD" => %w[ruby gen.rb ${_TARGET}],
-              "CMD_DESC" => "Generating")
-  env.produces("inc.c", "inc.h")
+    env.Command("inc.c",
+                [],
+                "CMD" => %w[ruby gen.rb ${_TARGET}],
+                "CMD_DESC" => "Generating")
+    env.produces("inc.c", "inc.h")
+  end
 end