From 8976d7dea23a306a0953c97f2ae947f7b5e64a15 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Fri, 27 Dec 2013 14:56:25 -0500
Subject: [PATCH] update README custom builder examples

---
 README.md | 37 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index bc72a66..14e24e3 100644
--- a/README.md
+++ b/README.md
@@ -66,7 +66,8 @@ end
 
 ```ruby
 class GenerateFoo < Rscons::Builder
-  def run(target, sources, cache, env, vars)
+  def run(target, sources, user_deps, cache, env, vars)
+    cache.mkdir_p(File.dirname(target))
     File.open(target, "w") do |fh|
       fh.puts <<EOF
 #define GENERATED 42
@@ -81,6 +82,40 @@ Rscons::Environment.new do |env|
 end
 ```
 
+### Example: Custom Builder That Only Regenerates When Necessary
+
+```ruby
+class CmdBuilder < Rscons::Builder
+  def run(target, sources, user_deps, cache, env, vars)
+    cmd = ["cmd", "-i", sources.first, "-o", target]
+    unless cache.up_to_date?(target, cmd, sources, user_deps)
+      cache.mkdir_p(File.dirname(target))
+      system(cmd)
+      cache.register_build(target, cmd, sources, user_deps)
+    end
+  end
+end
+
+Rscons::Environment.new do |env|
+  env.CmdBuilder("foo.gen", "foo_gen.cfg")
+end
+```
+
+### Example: Custom Builder Using Builder#standard_build()
+
+```ruby
+class CmdBuilder < Rscons::Builder
+  def run(target, sources, user_deps, cache, env, vars)
+    cmd = ["cmd", "-i", sources.first, "-o", target]
+    standard_build("CmdBld #{target}", target, cmd, sources, user_deps, env, cache)
+  end
+end
+
+Rscons::Environment.new do |env|
+  env.CmdBuilder("foo.gen", "foo_gen.cfg")
+end
+```
+
 ### Example: Using different compilation flags for some sources
 
 ```ruby