Turning an AST node / subnodes into something human-readable

Mark Lawrence breamoreboy at yahoo.co.uk
Wed Feb 19 16:04:29 CET 2014


On 19/02/2014 03:58, Chris Angelico wrote:
> I'm working with the ast module to do some analysis on Python
> codebases, and once I've found what I'm looking for, I want to print
> something out. The file name I'm hanging onto externally, so that
> works; and the nodes all have a lineno. So far so good. But how do I
> "reconstitute" a subtree into something fit for human consumption?
>
> Take this cut-down example:
>
> module = ast.parse("x[1] = 345+456")
> assign = list(ast.walk(module))[1]
> destination = assign.targets[0]
>
> At this point, destination is the subtree representing what's being
> assigned to. I can get a verbose dump of that:
>
>>>> print(ast.dump(destination))
> Subscript(value=Name(id='x', ctx=Load()), slice=Index(value=Num(n=1)),
> ctx=Store())
>
> but what I'd really like to do is get something that looks
> approximately like "x[1]". Is there an easy way to do that? Its str
> and repr aren't useful, and I can't see a "reconstitute" method on the
> node, nor a function in ast itself for the job. In theory I could
> write one, but it'd need to understand every node type, so it seems
> the most logical place would be on the node itself - maybe in __str__.
>
> Is there anything nice and easy? I don't care if it's not perfect, as
> long as it's more readable than ast.dump(). :)
>
> ChrisA
>

http://alexleone.blogspot.co.uk/2010/01/python-ast-pretty-printer.html ?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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