4.1.1 Interaction with dynamic features
There are several cases where Python statements are illegal when used in conjunction
with nested scopes that contain free variables.
If a variable is referenced in an enclosing scope, it is illegal to delete the name. An
error will be reported at compile time.
If the wild card form of import -- "import *" -- is
used in a function and the function contains or is a nested block with free variables, the
compiler will raise a SyntaxError.
If exec is used in a function and the function contains or is
a nested block with free variables, the compiler will raise a SyntaxError
unless the exec explicitly specifies the local namespace for the exec.
(In other words, "exec obj"would be illegal, but "exec obj in ns" would be legal.)
The eval(), execfile(), and input() functions and the exec statement do
not have access to the full environment for resolving names. Names may be resolved in the
local and global namespaces of the caller. Free variables are not resolved in the nearest
enclosing namespace, but in the global namespace.4.1The
exec statement and the eval() and execfile() functions have optional arguments to override the global
and local namespace. If only one namespace is specified, it is used for both.
Footnotes
- ... namespace.4.1
- This limitation occurs because the code that is executed by these operations is not
available at the time the module is compiled.
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