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gh-48496: Added example and link to faq for UnboundLocalError in reference #93068

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hauntsaninja merged 4 commits into from
Dec 22, 2022
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gh-48496: Added example and link to faq for UnboundLocalError in reference #93068

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8e34c35
Added example and link to faq for UnboundLocalError in reference
slateny May 22, 2022
260e171
Remove example as FAQ already contains one
slateny Dec 10, 2022
7026c3a
Readd space
slateny Dec 10, 2022
643ead6
Simplify wording
slateny Dec 22, 2022
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Added example and link to faq for UnboundLocalError in reference
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@slateny
slateny committed May 22, 2022
commit 8e34c351da29bd3e6f2a159b38bc7aadcb7e9ad2
2 changes: 2 additions & 0 deletions Doc/faq/programming.rst
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Expand Up @@ -111,6 +111,8 @@ Yes. The coding style required for standard library modules is documented as
Core Language
=============

.. _faq-unboundlocalerror:

Why am I getting an UnboundLocalError when the variable has a value?
--------------------------------------------------------------------

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16 changes: 15 additions & 1 deletion Doc/reference/executionmodel.rst
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Expand Up @@ -125,9 +125,23 @@ used, an :exc:`UnboundLocalError` exception is raised.
If a name binding operation occurs anywhere within a code block, all uses of the
name within the block are treated as references to the current block. This can
lead to errors when a name is used within a block before it is bound. This rule
is subtle. Python lacks declarations and allows name binding operations to
is subtle::

>>> x = 1
>>> def new_scope():
... print(x)
... x = 2
...
>>> new_scope()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<stdin>", line 2, in new_scope
UnboundLocalError: local variable 'x' referenced before assignment

Python lacks declarations and allows name binding operations to
occur anywhere within a code block. The local variables of a code block can be
determined by scanning the entire text of the block for name binding operations.
See also :ref:`the FAQ entry on UnboundLocalError <faq-unboundlocalerror>`.

If the :keyword:`global` statement occurs within a block, all uses of the names
specified in the statement refer to the bindings of those names in the top-level
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