pvData ctypes: added context handler and handle destructor to test example

testApp/capi/testc.cpp

@@ -76,6 +76,12 @@ extern "C"
         }
     }
 
+    void destroy(void * handle)
+    {
+        StructureHandle * sh = (StructureHandle *)handle;
+        delete sh;
+    }
+
 };
 
 

testApp/capi/testc.py

@@ -3,6 +3,8 @@
 import os
 from ctypes import *
 
+# cytpes API
+
 libname = "../../lib/%s/libtestc.so" % os.environ["EPICS_HOST_ARCH"]
 lib = CDLL(libname)
 lib.createTest.restype = c_void_p
@@ -18,16 +20,38 @@ lib.getScalarType.argtypes = [c_void_p, c_char_p]
 lib.getElementType.restype = c_int
 lib.getElementType.argtypes = [c_void_p, c_char_p]
 
+# Python API
+
 type_enum = ["scalar", "scalarArray", "structure", "structureArray"]
-struct = lib.createTest()
 
-l = lib.getNumberFields(struct)
-print "pvData structure has %d fields" % l
+class Structure:
+    def getNumberFields(self):
+        return lib.getNumberFields(self.handle)
+    def getFieldName(self, n):
+        return lib.getFieldName(self.handle, n)
+    def getFieldType(self, n):
+        return lib.getFieldType(self.handle, n)
+    def getScalarType(self, n):
+        return lib.getScalarType(self.handle, n)
+    def getElementType(self, n):
+        return lib.getElementType(self.handle, n)
+    def __enter__(self):
+        return self
+    def __exit__(self, a, b, c):
+        print "destroying handle"
+        lib.destroy(self.handle)
 
-for n in range(l):
-    name = lib.getFieldName(struct, n)
-    type_ = lib.getFieldType(struct, name)
-    sc_type = lib.getScalarType(struct, name)
-    el_type = lib.getElementType(struct, name)
-    print name, type_enum[type_], sc_type, el_type
-    
+class TestStructure(Structure):
+    def __init__(self):
+        self.handle = lib.createTest()
+
+with TestStructure() as s:
+    l = s.getNumberFields()
+    print "pvData structure has %d fields" % l
+    for n in range(l):
+        name = s.getFieldName(n)
+        type_ = s.getFieldType(name)
+        sc_type = s.getScalarType(name)
+        el_type = s.getElementType(name)
+        print name, type_enum[type_], sc_type, el_type
+