From 3f5aeee1c6836a127de37333829795439e14e4a7 Mon Sep 17 00:00:00 2001
From: "W. Trevor King" <wking@tremily.us>
Date: Wed, 17 Oct 2012 12:56:41 -0400
Subject: [PATCH] calibration: add Caldac.allocate() for stand-alone caldac
 instances.

---
 pycomedi/calibration.pxd |  1 +
 pycomedi/calibration.pyx | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/pycomedi/calibration.pxd b/pycomedi/calibration.pxd
index 047bf0b..cbd827b 100644
--- a/pycomedi/calibration.pxd
+++ b/pycomedi/calibration.pxd
@@ -35,6 +35,7 @@ cdef class CalibratedConverter (object):
 
 cdef class Caldac (object):
     cdef _comedilib_h.comedi_caldac_t *caldac
+    cdef bint _local
 
 
 cdef class CalibrationSetting (object):
diff --git a/pycomedi/calibration.pyx b/pycomedi/calibration.pyx
index 6e688b3..49f0028 100644
--- a/pycomedi/calibration.pyx
+++ b/pycomedi/calibration.pyx
@@ -234,9 +234,32 @@ cdef class Caldac (object):
     <Caldac subdevice:5 channel:4 value:255>
 
     >>> d.close()
+
+    You can also allocate `Caldac` instances on your own.  The
+    allocated memory will be automatically freed when the instance is
+    garbage collected.
+
+    >>> caldac = Caldac()
+    >>> caldac.subdevice == None
+    True
+    >>> caldac.subdevice = 1
+    Traceback (most recent call last):
+      ...
+    AssertionError: load caldac first
+    >>> caldac.allocate()
+    >>> caldac.subdevice
+    0L
+    >>> caldac.subdevice = 1
     """
     def __cinit__(self):
         self.caldac = NULL
+        self._local = False
+
+    def __dealloc__(self):
+        if self.caldac is not NULL and self._local:
+            _stdlib.free(self.caldac)
+            self.caldac = NULL
+            self._local = False
 
     def __str__(self):
         fields = ['{}:{}'.format(f, getattr(self, f))
@@ -246,6 +269,17 @@ cdef class Caldac (object):
     def __repr__(self):
         return self.__str__()
 
+    def allocate(self):
+        assert not self._local, 'already allocated'
+        self.caldac = <_comedilib_h.comedi_caldac_t *> _stdlib.malloc(
+            sizeof(_comedilib_h.comedi_caldac_t *))
+        if self.caldac is NULL:
+            raise MemoryError()
+        self._local = True
+        self.subdevice = 0
+        self.channel = 0
+        self.value = 0
+
     def _subdevice_get(self):
         if self.caldac is not NULL:
             return self.caldac.subdevice
-- 
2.26.2