Revert "Remove (mostly) unused C print functions in linear package"

This reverts commit f9e41dec2860090e00dd1e0fb74c1beb79197ae5.

linear_models/cfuncs.go

@@ -0,0 +1,14 @@
+// +build go1.2
+
+package linear_models
+
+/*
+
+void libLinearPrintFunc(char *);
+
+void golearn_liblinear_print_func_cgo(char *c) {
+    libLinearPrintFunc(c);
+}
+
+*/
+import "C"

linear_models/liblinear.go

@@ -59,6 +59,7 @@ func NewProblem(X [][]float64, y []float64, bias float64) *Problem {
 }
 
 func Train(prob *Problem, param *Parameter) *Model {
+	libLinearHookPrintFunc() // Sets up logging
 	return &Model{C.train(&prob.c_prob, &param.c_param)}
 }
 

linear_models/liblinear_print.go

@@ -0,0 +1,27 @@
+// +build go1.2
+
+package linear_models
+
+/*
+#cgo LDFLAGS: -llinear
+#cgo CFLAGS:
+#include <linear.h>
+
+typedef void (*print_func)(char *);
+void golearn_liblinear_print_func_cgo(char *);
+*/
+import "C"
+
+import (
+	"fmt"
+	"unsafe"
+)
+
+//export libLinearPrintFunc
+func libLinearPrintFunc(str *C.char) {
+	fmt.Println(C.GoString(str))
+}
+
+func libLinearHookPrintFunc() {
+	C.set_print_string_function((C.print_func)(unsafe.Pointer(C.golearn_liblinear_print_func_cgo)))
+}

linear_models/liblinear_print_11.go

@@ -0,0 +1,16 @@
+// +build go1.1
+// +build !go1.2
+// +build !go1.3
+
+package linear_models
+
+import "C"
+
+//export libLinearPrintFunc
+func libLinearPrintFunc(str *C.char) {
+	// Stubbed
+}
+
+func libLinearHookPrintFunc() {
+	// Stubbed
+}