Statespressions? (Re: Draft Pep (was: Re: Let's Talk About Lambda Functions!))

[Duncan Booth]

Michael Hudson <mwh at python.net> wrote in 
news:lkadnxog0r.fsf at pc150.maths.bris.ac.uk:

> Duncan Booth <duncan at NOSPAMrcp.co.uk> writes:
> 
>> You can probably build a new code object using new.code(), but with 14 
>> arguments to be passed in I can't be bothered showing an example.
> 
> I have this useful function lying around:
> 
<snipped function with a lot of arguments>
 
> So you can go
> 
> new_code = copy_code_with_changes(old_code, name="case a")
> 
> pychecker complains that it has too many arguments...
> 
> Cheers,
> M.
> 
Oh alright, here is my take on your function, along with a genuinely 
anonymous function builder:

--------------------
import new

def copy_code_with_changes(code, **kw):
    args = []

    for name in ('argcount','nlocals','stacksize','flags',
        'code','consts','names','varnames','filename',
        'name','firstlineno','lnotab'):
            args.append(kw.get(name, getattr(code, 'co_'+name)))
    return new.code(*args)

def rename_function(fn, name):
    code = copy_code_with_changes(fn.func_code, name=name)
    return new.function(code, fn.func_globals, name)

def test():
    raise RuntimeError

x = rename_function(test, '<anonymous>')

x()
-------------------
Which produces the output:
D:\temp>code.py
Traceback (most recent call last):
  File "D:\temp\code.py", line 21, in ?
    x()
  File "D:\temp\code.py", line 17, in <anonymous>
    raise RuntimeError
RuntimeError



-- 
Duncan Booth                                             duncan at rcp.co.uk
int month(char *p){return(124864/((p[0]+p[1]-p[2]&0x1f)+1)%12)["\5\x8\3"
"\6\7\xb\1\x9\xa\2\0\4"];} // Who said my code was obscure?