Lazy Python usage (hack request)

[Emile van Sebille]

Hi Pearu,

You've got some interesting questions today. ;-)  You did
ask for a hack, and you don't place a restriction on how
python is invoked, so, yes, I think this can be done.  Using
popen2, you could accept input, pass it through to python,
and display output.  In between, you can validate and play
behind the scenes games to get the session results you ask
for.

This is probably only useful for light interactive sessions,
but I do think it would work, and you wouldn't even need to
import lazy.

--

Emile van Sebille
emile at fenx.com
-------------------


"Pearu Peterson" <pearu at ioc.ee> wrote in message
news:Pine.LNX.4.10.10012301443330.13756-100000 at kev.ioc.ee...
>
> Hi,
>
> Is it possible to achive the following behavior in Python?
>
> >>> import lazy
> >>> a = b
> No name 'b' defined, using default 777
> >>> print a
> 777
>
> Note that changing the python session above is not an
option. (Also 'No'
> for the answer;-)
>
> Just to avoid questions 'Why do you need it?', I would use
it in
> PySymbolic (but not in its Kernel!) for defining new
Symbol instances in
> fly (it's very tedious to define 'b = Symbol("b")',etc all
the time).
>
> Here lazy.py would be something like the following:
> #Begin of lazy.py
>
> import UserDict,sys
>
> class myDict(UserDict.UserDict):
>     def __getitem__(self, key):
>         if not self.data.has_key(key):
>             print 'No name %s defined, using default
777'%(`key`)
>             self.data[key] = 777
>         return self.data[key]
>
> sys.modules['__builtin__'].__dict__ =
myDict(sys.modules['__builtin__'].__dict__)
>
> #EOF lazy.py
>
> When trying to set sys.modules['__builtin__'].__dict__, an
exception
> TypeError: read-only special attribute
> is raised.
>
> Is there anyway to go around that? May be in C level?
>
> Any hints, suggestions, or similar are appreciated.
>
> Thanks,
> Pearu
>