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<title>19.3.3 Examples
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<H2><A NAME=
"SECTION0021330000000000000000">
This section shows several simple examples of ASTs for Python source
code. The examples demonstrate how to use the
<tt class=
"function">parse()
</tt>
function, what the repr of an AST looks like, and how to access
attributes of an AST node.
The first module defines a single function. Assume it is stored in
<span class=
"file">/tmp/doublelib.py
</span>.
<div class=
"verbatim"><pre>
"""This is an example module.
"Return twice the argument"
In the interactive interpreter session below, I have reformatted the
long AST reprs for readability. The AST reprs use unqualified class
names. If you want to create an instance from a repr, you must import
the class names from the
<tt class=
"module">compiler.ast
</tt> module.
<div class=
"verbatim"><pre>
>>> import compiler
>>> mod = compiler.parseFile(
"/tmp/doublelib.py")
Module('This is an example module.\n\nThis is the docstring.\n',
Stmt([Function(None, 'double', ['x'], [],
0,
'Return twice the argument',
Stmt([Return(Mul((Name('x'), Const(
2))))]))]))
>>> from compiler.ast import *
>>> Module('This is an example module.\n\nThis is the docstring.\n',
... Stmt([Function(None, 'double', ['x'], [],
0,
... 'Return twice the argument',
... Stmt([Return(Mul((Name('x'), Const(
2))))]))]))
Module('This is an example module.\n\nThis is the docstring.\n',
Stmt([Function(None, 'double', ['x'], [],
0,
'Return twice the argument',
Stmt([Return(Mul((Name('x'), Const(
2))))]))]))
'This is an example module.\n\nThis is the docstring.\n'
>>> for node in mod.node.nodes:
Function(None, 'double', ['x'], [],
0, 'Return twice the argument',
Stmt([Return(Mul((Name('x'), Const(
2))))]))
>>> func = mod.node.nodes[
0]
Stmt([Return(Mul((Name('x'), Const(
2))))])
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<span class=
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2.4.2, documentation updated on
28 September
2005.
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