RF - convert default_structarr to classmethod

It makes more sense for this method not to require an instance.

Author: matthew-brett

nibabel/analyze.py

@@ -327,10 +327,11 @@ def _guessed_endian(self, hdr):
             return native_code
         return swapped_code
 
-    def default_structarr(self, endianness=None):
+    @classmethod
+    def default_structarr(klass, endianness=None):
         ''' Return header data for empty header with given endianness
         '''
-        hdr_data = super(AnalyzeHeader, self).default_structarr(endianness)
+        hdr_data = super(AnalyzeHeader, klass).default_structarr(endianness)
         hdr_data['sizeof_hdr'] = 348
         hdr_data['dim'] = 1
         hdr_data['dim'][0] = 0

nibabel/nifti1.py

@@ -504,8 +504,8 @@ def from_fileobj(klass, fileobj, size, byteswap):
 
 
 class Nifti1Header(SpmAnalyzeHeader):
-    ''' Class for NIFTI1 header 
-    
+    ''' Class for NIFTI1 header
+
     The NIFTI1 header has many more coded fields than the simpler Analyze
     variants.  Nifti1 headers also have extensions.
 
@@ -608,11 +608,11 @@ def get_best_affine(self):
             return self.get_qform()
         return self.get_base_affine()
 
-    def default_structarr(self, endianness=None):
+    @classmethod
+    def default_structarr(klass, endianness=None):
         ''' Create empty header binary block with given endianness '''
-        hdr_data = analyze.AnalyzeHeader.default_structarr(self, endianness)
-        hdr_data['scl_slope'] = 1
-        if self.is_single:
+        hdr_data = super(Nifti1Header, klass).default_structarr(endianness)
+        if klass.is_single:
             hdr_data['magic'] = 'n+1'
             hdr_data['vox_offset'] = 352
         else:

nibabel/spm99analyze.py

@@ -43,9 +43,10 @@ class SpmAnalyzeHeader(analyze.AnalyzeHeader):
     has_data_slope = True
     has_data_intercept = False
 
-    def default_structarr(self, endianness=None):
+    @classmethod
+    def default_structarr(klass, endianness=None):
         ''' Create empty header binary block with given endianness '''
-        hdr_data = super(SpmAnalyzeHeader, self).default_structarr(endianness)
+        hdr_data = super(SpmAnalyzeHeader, klass).default_structarr(endianness)
         hdr_data['scl_slope'] = 1
         return hdr_data
 

nibabel/tests/test_wrapstruct.py

@@ -49,7 +49,7 @@ class MyWrapStruct(WrapStruct):
     """ An example binary header class """
     _field_recoders = {}
     dtype_def = [
-        ('an_integer', 'i4'),
+        ('an_integer', 'i2'),
         ('a_str', 'S10')]
     _dtype = np.dtype(dtype_def)
 
@@ -58,9 +58,9 @@ def _guessed_endian(self, hdr):
             return native_code
         return swapped_code
 
-    def default_structarr(self, endianness=None):
-        structarr = super(MyWrapStruct, self).default_structarr(
-            endianness)
+    @classmethod
+    def default_structarr(klass, endianness=None):
+        structarr = super(MyWrapStruct, klass).default_structarr(endianness)
         structarr['an_integer'] = 1
         structarr['a_str'] = 'a string'
         return structarr

nibabel/wrapstruct.py

@@ -146,7 +146,7 @@ def __init__(self,
         array(1, dtype=int16)
         '''
         if binaryblock is None:
-            self._structarr = self.default_structarr(endianness)
+            self._structarr = self.__class__.default_structarr(endianness)
             return
         # check size
         if len(binaryblock) != self._dtype.itemsize:
@@ -367,15 +367,15 @@ def _guessed_endian(self, wstr):
         '''
         raise NotImplementedError
 
-    def default_structarr(self, endianness=None):
+    @classmethod
+    def default_structarr(klass, endianness=None):
         ''' Return structured array for default structure, with given endianness
         '''
-        dt = self._dtype
+        dt = klass._dtype
         if endianness is not None:
             endianness = endian_codes[endianness]
             dt = dt.newbyteorder(endianness)
-        wstr_data = np.zeros((), dtype=dt)
-        return wstr_data
+        return np.zeros((), dtype=dt)
 
     @property
     def structarr(self):