Allow Bind() to take a Callback<> and bind all its free parameters.

Basically, turns base::Callback<void(...)> to base::Closure.

It turns out there are a number of use caess where an API takes a callback, and then wants to invoke the Callback on another thread. This piece of syntactic sugar removes the need for custom helper functions.

This isn't quite full currying, however it is much simpler to implement.  

BUG=87287
TEST=none


Review URL: http://codereview.chromium.org/8073012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@103446 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 35 insertions, 0 deletions

diff --git a/base/bind_unittest.cc b/base/bind_unittest.cc
index dde2226..0c24710 100644
--- a/base/bind_unittest.cc
+++ b/base/bind_unittest.cc
@@ -153,6 +153,10 @@ int Sum(int a, int b, int c, int d, int e, int f) {
   return a + b + c + d + e + f;
 }
 
+void OutputSum(int* output, int a, int b, int c, int d, int e) {
+  *output = a + b + c + d + e;
+}
+
 const char* CStringIdentity(const char* s) {
   return s;
 }
@@ -243,6 +247,37 @@ TEST_F(BindTest, ArityTest) {
   EXPECT_EQ(69, c6.Run(13, 12, 11, 10, 9, 14));
 }
 
+// Bind should be able to take existing Callbacks and convert to a Closure.
+TEST_F(BindTest, CallbackBindMore) {
+  int output = 0;
+  Closure c;
+
+  Callback<void(int)> c1 = Bind(&OutputSum, &output, 16, 8, 4, 2);
+  c = Bind(c1, 10);
+  c.Run();
+  EXPECT_EQ(40, output);
+
+  Callback<void(int,int)> c2 = Bind(&OutputSum, &output, 16, 8, 4);
+  c = Bind(c2, 10, 9);
+  c.Run();
+  EXPECT_EQ(47, output);
+
+  Callback<void(int,int,int)> c3 = Bind(&OutputSum, &output, 16, 8);
+  c = Bind(c3, 10, 9, 8);
+  c.Run();
+  EXPECT_EQ(51, output);
+
+  Callback<void(int,int,int,int)> c4 = Bind(&OutputSum, &output, 16);
+  c = Bind(c4, 10, 9, 8, 7);
+  c.Run();
+  EXPECT_EQ(50, output);
+
+  Callback<void(int,int,int,int,int)> c5 = Bind(&OutputSum, &output);
+  c = Bind(c5, 10, 9, 8, 7, 6);
+  c.Run();
+  EXPECT_EQ(40, output);
+}
+
 // Function type support.
 //   - Normal function.
 //   - Normal function bound with non-refcounted first argument.