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@@ -190,9 +190,10 @@ class Int(int,Hilite): pass
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# Reassignment and deletion forbidden
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class MMGenImmutableAttr(object): # Descriptor
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- def __init__(self,name,dtype,typeconv=True,no_type_check=False):
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+ def __init__(self,name,dtype,typeconv=True,no_type_check=False,set_none_ok=False):
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self.typeconv = typeconv
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self.no_type_check = no_type_check
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+ self.set_none_ok = set_none_ok
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assert isinstance(dtype,(str,type,type(None))),'{!r}: invalid dtype arg'.format(dtype)
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self.name = name
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self.dtype = dtype
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@@ -209,7 +210,9 @@ class MMGenImmutableAttr(object): # Descriptor
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if not self.set_attr_ok(instance):
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m = "Attribute '{}' of {} instance cannot be reassigned"
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raise AttributeError(m.format(self.name,type(instance)))
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- if self.typeconv: # convert type
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+ if self.set_none_ok and value == None:
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+ instance.__dict__[self.name] = None
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+ elif self.typeconv: # convert type
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instance.__dict__[self.name] = \
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globals()[self.dtype](value,on_fail='raise') if type(self.dtype) == str else self.dtype(value)
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else: # check type
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