Default argument value is mutable

Hello, @wengong-jin !

My IDE prevents me that default argument value is mutable (MolTreeNode class). I want to make sure you understand that default argument values are really mutable and in Python we have the following behaviour:

def append_to(element, to=[]):
    to.append(element)
    return to

my_list = append_to(12)
print(my_list)

my_other_list = append_to(42)
print(my_other_list)

Output: [12] [12, 42]

Did you use it as trick? For example, in MolTreeNode class? Also I see the same problem in enum_assemble function in chemutils.py

[Oktai15]

@wengong-jin Don’t you think that it can influence on training and, therefore, result? Because your program could be use previous state of list. Can you check that moment?

It refers to create new instance of MolTreeNode and call enum_assemble function. MolTreeNode: super_root = MolTreeNode("") – jtnn_dec.py root = MolTreeNode(self.vocab.get_smiles(root_wid)) – jtnn_dec.py node_y = MolTreeNode(self.vocab.get_smiles(wid)) – jtnn_dec.py node_y = MolTreeNode(self.vocab.get_smiles(next_wid)) – jtnn_dec.py enum_assemble: cands = enum_assemble(self, neighbors) – mol_tree.py cands = enum_assemble(node_x, neighbors) – jtnn_dec.py

Also, this problem may cause of this https://github.com/wengong-jin/icml18-jtnn/issues/9 issue

[wengong-jin]

I don’t think this problem will cause memory issues.