golang: Fix `@func(cls) def name` not to set `name` in calling context
This is take 2 after 924a808c (golang: Fix @func(cls) def name
not to
override name
in calling context). There we fixed it not to override
name if name was already set, but for the case of unset name it was
still set. The following example was thus not working correctly as
builtin next
was overridden:
class BitSync
@func(BitSync)
def next(): ... # this was shadowing access to builtin next
def peek(seq):
return next(...) # here next was taken not from builtin, but
# from result of above shadowing
To solve the problem in the patch from 2019 I initially contemplated patching bytecode because python unconditionally does STORE_NAME after a function is defined with decorator:
In [2]: c = """
...: @fff
...: def ccc():
...: return 1
...: """
In [3]: cc = compile(c, "file", "exec")
In [4]: dis(cc)
2 0 LOAD_NAME 0 (fff)
3 LOAD_CONST 0 (<code object ccc at 0x7fafe58d0130, file "file", line 2>)
6 MAKE_FUNCTION 0
9 CALL_FUNCTION 1
12 STORE_NAME 1 (ccc) <-- NOTE means: ccc = what fff() call returns
15 LOAD_CONST 1 (None)
18 RETURN_VALUE
However after hitting this problem for real again and taking a fresh look I found a way to arrange for the good end result without bytecode magic: if name is initially unset @func can install its own custom object, which, when overwritten by normal python codeflow of invoking STORE_NAME after decorator, unsets the attribute.
That works quite ok and the patch with the fix is small.
/cc @jerome