evaluate positional defaults before keyword-only defaults (closes #16967)

1 files changed, 9 insertions, 8 deletions

diff --git a/Doc/reference/compound_stmts.rst b/Doc/reference/compound_stmts.rst
index d0d0646..c25c767 100644
--- a/Doc/reference/compound_stmts.rst
+++ b/Doc/reference/compound_stmts.rst
@@ -493,14 +493,15 @@ case the parameter's default value is substituted.  If a parameter has a default
 value, all following parameters up until the "``*``" must also have a default
 value --- this is a syntactic restriction that is not expressed by the grammar.
 
-**Default parameter values are evaluated when the function definition is
-executed.** This means that the expression is evaluated once, when the function
-is defined, and that the same "pre-computed" value is used for each call.  This
-is especially important to understand when a default parameter is a mutable
-object, such as a list or a dictionary: if the function modifies the object
-(e.g. by appending an item to a list), the default value is in effect modified.
-This is generally not what was intended.  A way around this is to use ``None``
-as the default, and explicitly test for it in the body of the function, e.g.::
+**Default parameter values are evaluated from left to right when the function
+definition is executed.** This means that the expression is evaluated once, when
+the function is defined, and that the same "pre-computed" value is used for each
+call.  This is especially important to understand when a default parameter is a
+mutable object, such as a list or a dictionary: if the function modifies the
+object (e.g. by appending an item to a list), the default value is in effect
+modified.  This is generally not what was intended.  A way around this is to use
+``None`` as the default, and explicitly test for it in the body of the function,
+e.g.::
 
    def whats_on_the_telly(penguin=None):
        if penguin is None: