[Python-Dev] Dropping decorator syntax for 2.4?

[Jeremy Hylton]

On Fri, 04 Jun 2004 11:59:46 +0200, Thomas Heller <theller at python.net> wrote:
> 
> Couldn't Guido's syntax be implemented as a combination of an import
> hook together with a byte code hack, without direct support in the core?
> 
> Code like this
> 
>   [decorator1, decorator2]
>   def func(args):
>       pass

How about this?

[decorator1, decorator2]
if 0:
    print "Obscure corner case?"
def func(args):
    pass
 
> seems to be compiled into these byte codes
>              ....
>            6 BUILD_LIST
>            9 POP_TOP
>           10 LOAD_CONST               0 (<code object test at 0091FD20, ...)
>           13 MAKE_FUNCTION            0
>           16 STORE_NAME               2 (test)
> 
> It seems BUILD_LIST / POP_TOP / LOAD_CONST / MAKE_FUNCTION is the
> sequence which should trigger the magic.

I don't recall Guido's patch.  Did he modify the grammar or can it all
be done inside the compiler?  Not that it's practical for 2.4, but I
think it wouldn't be hard to post-process the existing AST to
recognize decorators written like this.

You'd like for adjacent statements of the form:
    Expr(List())
    FunctionDef()
and replace them with a single
    FunctionDef()

Or do we need to catch Expr(ListComp()) too?  PEP 318 doesn't mention
semantics anywhere, so it doesn't say what is allowed inside the
square brackets.

Jeremy