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What is ast.alias(name, asname) in Python?
Abdul Monum
ast.alias(name, asname) is a class defined in the ast module that is used to express an parse() method of ast is called on a Python source code that contains an alias, the ast.alias(name, asname) class is invoked, which expresses the alias to a node in an ast tree data structure. The ast.alias class represents the alias node type in the ast tree. In the class parameter, name, and asname contain raw strings of the names. If the as keyword is not used, then asname is None.
Example
import ast
from pprint import pprint
class AliasVisitor(ast.NodeVisitor):
def visit_Import(self, node):
print('Node type: Import\nFields:', node._fields)
ast.NodeVisitor.generic_visit(self, node)
def visit_alias(self, node):
print('Node type: alias\nFields:', node._fields)
ast.NodeVisitor.generic_visit(self, node)
visitor = AliasVisitor()
tree = ast.parse('import numpy as np')
pprint(ast.dump(tree))
visitor.visit(tree)
Explanation
- We define an
AliasVisitorclass that extends from the parent classast.NodeVisitor. We override the predefinedvisit_Importandvisit_aliasmethods in the parent class, which receive theImportandaliasnodes, respectively. In the method, we print the type and the fields inside the node and call thegeneric_visit()method, which invokes the propagation of visit on the children nodes of the input node. - We initialize a
visitorobject of the classAliasVisitor. - We write the Python statement
import numpy as npand send it to theast.parse()method, which returns the result of the expression after evaluation, and store the result intree. - The
ast.dump()method returns a formatted string of the tree structure intree. - The
visitmethod available to thevisitorobject visits all the nodes in the tree structure.
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Abdul Monum
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