using the value stored in the ._field attribute in python ast

Question

This question is a result of my python ast work.

I have a node in the ast and I want to obtain its children.

The ._field attribute gives the names of all the children of a node. However it is different for different node depending upon the syntax node.

for example if node is of type BinOp..then node._field will yield ('left','op', 'right')

Hence to access the children of node I have to use node.left, node.op and node.right

But I want to do it for any general node.

given any node if I use node._field it will give me a tupple. How do I use this tupple for obtaining the children. The node can be any general node. So I do not know what the tuple would be like beforehand.

examples in form of codes will be really nice! Thanks!

Sven Marnach · Accepted Answer · 2011-05-16 13:23:14Z

2

To iterate over the children of an arbitrary node, use ast.iter_child_nodes(). To iterate over the fields instead, use ast.iter_fields().

answered May 16, 2011 at 13:23

Sven Marnach

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3 Comments

ncoghlan Over a year ago

Alternatively, use ast.NodeVisitor or ast.NodeTransformer to handle the tree traversal, and just implement the methods relevant to the nodes of interest.

Adwaitvedant Over a year ago

thanks for your reply! i wrote the following code st=ast.parse('5+a') print ast.iter_child_nodes(st) ..... output was <generator object iter_child_nodes at 0xb763de8> the output instead should have been the child of it.. an ast.expr object

Sven Marnach Over a year ago

@Adwait: These functions are meant to iterate over, so try for child in ast.iter_child_nodes(st).

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