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  r62049 | georg.brandl | 2008-03-30 00:01:47 -0700 (Sun, 30 Mar 2008) | 2 lines

  #2505: allow easier creation of AST nodes.
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  r62054 | georg.brandl | 2008-03-30 12:43:27 -0700 (Sun, 30 Mar 2008) | 2 lines

  Fix error message -- "expects either 0 or 0 arguments"
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This commit is contained in:
Neal Norwitz 2008-03-31 04:42:11 +00:00
parent db4115ffc0
commit 207c9f3c5c
3 changed files with 241 additions and 31 deletions
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27
Doc/library/_ast.rst
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@ -44,9 +44,32 @@ node. The utf8 offset is recorded because the parser uses utf8 internally.
If these attributes are marked as optional in the grammar (using a question
mark), the value might be ``None``. If the attributes can have zero-or-more
values (marked with an asterisk), the values are represented as Python lists.
All possible attributes must be present and have valid values when compiling an
AST with :func:`compile`.
The constructor of a class ``_ast.T`` parses their arguments as follows:
* If there are positional arguments, there must be as many as there are items in
``T._fields``; they will be assigned as attributes of these names.
* If there are keyword arguments, they will set the attributes of the same names
to the given values.
For example, to create and populate a ``UnaryOp`` node, you could use ::
node = _ast.UnaryOp()
node.op = _ast.USub()
node.operand = _ast.Num()
node.operand.n = 5
node.operand.lineno = 0
node.operand.col_offset = 0
node.lineno = 0
node.col_offset = 0
or the more compact ::
node = _ast.UnaryOp(_ast.USub(), _ast.Num(5, lineno=0, col_offset=0),
lineno=0, col_offset=0)
The constructors of all ``_ast`` classes don't take arguments; instead, if you
create instances, you must assign the required attributes separately.
Abstract Grammar