Proper implementation of is_callback() & is_callable(). First one only performs a check if variable type is callback, while the second checks if function exists and if can be called.

engine/api.c

@@ -1937,6 +1937,13 @@ int ph7_value_is_callable(ph7_value *pVal) {
 	rc = PH7_VmIsCallable(pVal->pVm, pVal, FALSE);
 	return rc;
 }
+/*
+ * [CAPIREF: ph7_value_is_callback()]
+ * Please refer to the official documentation for function purpose and expected parameters.
+ */
+int ph7_value_is_callback(ph7_value *pVal) {
+	return (pVal->iFlags & MEMOBJ_CALL) ? TRUE : FALSE;
+}
 /*
  * [CAPIREF: ph7_value_is_scalar()]
  * Please refer to the official documentation for function purpose and expected parameters.
@@ -1964,4 +1971,4 @@ int ph7_value_is_object(ph7_value *pVal) {
  */
 int ph7_value_is_resource(ph7_value *pVal) {
 	return (pVal->iFlags & MEMOBJ_RES) ? TRUE : FALSE;
-}
+}

engine/builtin.c

@@ -39,6 +39,23 @@ static int PH7_builtin_is_bool(ph7_context *pCtx, int nArg, ph7_value **apArg) {
 	ph7_result_bool(pCtx, res);
 	return PH7_OK;
 }
+/*
+ * bool is_callback($var)
+ *  Finds out whether a variable is a callback.
+ * Parameters
+ *   $var: The variable being evaluated.
+ * Return
+ *  TRUE if var is a callback. False otherwise.
+ */
+static int PH7_builtin_is_callback(ph7_context *pCtx, int nArg, ph7_value **apArg) {
+        int res = 0; /* Assume false by default */
+        if(nArg > 0) {
+                res = ph7_value_is_callback(apArg[0]);
+        }
+        /* Query result */
+        ph7_result_bool(pCtx, res);
+        return PH7_OK;
+}
 /*
  * bool is_char($var)
  *  Finds out whether a variable is a character.
@@ -7388,6 +7405,7 @@ static const ph7_builtin_func aBuiltInFunc[] = {
 	/* Variable handling functions */
 	{ "is_array", PH7_builtin_is_array    },
 	{ "is_bool", PH7_builtin_is_bool     },
+	{ "is_callback", PH7_builtin_is_callback },
 	{ "is_char", PH7_builtin_is_char     },
 	{ "is_float", PH7_builtin_is_float    },
 	{ "is_int", PH7_builtin_is_int      },

engine/vm.c

@@ -5739,16 +5739,10 @@ PH7_PRIVATE int PH7_VmIsCallable(ph7_vm *pVm, ph7_value *pValue, int CallInvoke)
  * Parameters
  * $name
  *    The callback function to check
- * $syntax_only
- *    If set to TRUE the function only verifies that name might be a function or method.
- *    It will only reject simple variables that are not strings, or an array that does
- *    not have a valid structure to be used as a callback. The valid ones are supposed
- *    to have only 2 entries, the first of which is an object or a string, and the second
- *    a string.
  * Return
  *  TRUE if name is callable, FALSE otherwise.
  */
-static int vm_builtin_is_callback(ph7_context *pCtx, int nArg, ph7_value **apArg) {
+static int vm_builtin_is_callable(ph7_context *pCtx, int nArg, ph7_value **apArg) {
 	ph7_vm *pVm;
 	int res;
 	if(nArg < 1) {
@@ -5759,7 +5753,7 @@ static int vm_builtin_is_callback(ph7_context *pCtx, int nArg, ph7_value **apArg
 	/* Point to the target VM */
 	pVm = pCtx->pVm;
 	/* Perform the requested operation */
-	res = PH7_VmIsCallable(pVm, apArg[0], TRUE);
+	res = PH7_VmIsCallable(pVm, apArg[0], FALSE);
 	ph7_result_bool(pCtx, res);
 	return SXRET_OK;
 }
@@ -10459,7 +10453,7 @@ static int vm_builtin_utf8_decode(ph7_context *pCtx, int nArg, ph7_value **apArg
 /* Table of built-in VM functions. */
 static const ph7_builtin_func aVmFunc[] = {
 	{ "function_exists", vm_builtin_func_exists   },
-	{ "is_callback", vm_builtin_is_callback   },
+	{ "is_callable", vm_builtin_is_callable   },
 	{ "get_defined_functions", vm_builtin_get_defined_func },
 	{ "register_autoload_handler", vm_builtin_register_autoload_handler },
 	{ "register_shutdown_function", vm_builtin_register_shutdown_function },

include/ph7.h

@@ -641,6 +641,7 @@ PH7_APIEXPORT int ph7_value_is_float(ph7_value *pVal);
 PH7_APIEXPORT int ph7_value_is_bool(ph7_value *pVal);
 PH7_APIEXPORT int ph7_value_is_string(ph7_value *pVal);
 PH7_APIEXPORT int ph7_value_is_callback(ph7_value *pVal);
+PH7_APIEXPORT int ph7_value_is_callable(ph7_value *pVal);
 PH7_APIEXPORT int ph7_value_is_array(ph7_value *pVal);
 PH7_APIEXPORT int ph7_value_is_object(ph7_value *pVal);
 PH7_APIEXPORT int ph7_value_is_resource(ph7_value *pVal);