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copied!<p>You can do this, but the solution is relatively slow (about 22µs per call on my machine). The answer is for the C code to use C thread primitives to communicate with another goroutine that will actually run the callback.</p> <p>I have created a Go package that provides this functionality: <a href="http://code.google.com/p/rog-go/source/browse/exp/callback/" rel="nofollow">rog-go.googlecode.com/hg/exp/callback</a>. There is an example package demonstrating its use <a href="http://code.google.com/p/rog-go/source/browse/exp/example/looper/looper.go" rel="nofollow">here</a>. The example demonstrates a call back to an arbitrary Go closure from a thread created outside of the Go runtime. Another example is <a href="http://code.google.com/p/rog-go/source/browse/exp/example/event" rel="nofollow">here</a>. This demonstrates a typical C callback interface and layers a Go callback on top of it.</p> <p>To try out the first example:</p> <pre><code>goinstall rog-go.googlecode.com/hg/exp/example/looper cd $GOROOT/src/pkg/rog-go.googlecode.com/hg/exp/example/looper gotest </code></pre> <p>To try out the second example:</p> <pre><code>goinstall rog-go.googlecode.com/hg/exp/example/event cd $GOROOT/src/pkg/rog-go.googlecode.com/hg/exp/example/event gotest </code></pre> <p>Both examples assume that pthreads are available. Of course, this is just a stop-gap measure until cgo is fixed, but the technique for calling arbitrary Go closures in a C callback will be applicable even then.</p> <p>Here is the documentation for the callback package:</p> <p><strong>PACKAGE</strong></p> <pre><code>package callback import "rog-go.googlecode.com/hg/exp/callback" </code></pre> <p><strong>VARIABLES</strong></p> <pre><code>var Func = callbackFunc </code></pre> <p>Func holds a pointer to the C callback function. When called, it calls the provided function f in a a Go context with the given argument.</p> <p>It can be used by first converting it to a function pointer and then calling from C. Here is an example that sets up the callback function:</p> <pre><code>//static void (*callback)(void (*f)(void*), void *arg); //void setCallback(void *c){ // callback = c; //} import "C" import "rog-go.googlecode.com/hg/exp/callback" func init() { C.setCallback(callback.Func) } </code></pre>

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