add from_file, add test

Author: oesteban

nipype/interfaces/base.py

@@ -758,14 +758,18 @@ class BaseInterface(Interface):
     _additional_metadata = []
     _redirect_x = False
 
-    def __init__(self, **inputs):
+    def __init__(self, from_file=None, **inputs):
         if not self.input_spec:
             raise Exception('No input_spec in class: %s' %
                             self.__class__.__name__)
         self.inputs = self.input_spec(**inputs)
         self.estimated_memory_gb = 1
         self.num_threads = 1
 
+        if from_file is not None:
+            self.load_inputs_from_json(from_file)
+
+
     @classmethod
     def help(cls, returnhelp=False):
         """ Prints class help

nipype/interfaces/tests/test_base.py

@@ -480,6 +480,8 @@ def __init__(self, **inputs):
     bif2.load_inputs_from_json(tmp_json)
     yield assert_equal, inputs_dict, bif2.inputs.get()
 
+    bif3 = DerivedInterface(from_file=tmp_json)
+    yield assert_equal, inputs_dict, bif3.inputs.get()
 
 def assert_not_raises(fn, *args, **kwargs):
     fn(*args, **kwargs)