(3.2) Overload print() using the C API?

[Peter Faulks]

On 27/04/2012 6:55 PM, Stefan Behnel wrote:
> Peter Faulks, 27.04.2012 10:36:
>> On 27/04/2012 5:15 PM, Stefan Behnel wrote:
>>> Peter Faulks, 26.04.2012 19:57:
>>>> I want to extend an embedded interpreter so that calls to print() are
>>>> automagically sent to a C++ gui (windows exe) via a callback function in
>>>> the DLL.
>>>>
>>>> Then I'll be able to do this:
>>>>
>>>> ----test.py----
>>>> import printoverload
>>>>
>>>> printoverload.set_stdout()
>>>> printoverload.set_stderr()
>>>>
>>>> print("this will be sent to a C function in printoverload.pyd")
>>>> ---------------
>>>
>>> Why would you want to divert only "print" instead of changing sys.stdout in
>>> general? Not all output comes from print calls.
>>>
>> Because I don't want to have to poll the stdout buffer.
>
> You don't have to. It's delivered right at your door and even rings the
> bell when it arrives to hand over the parcel in person.
>
>
>> I want the script
>> itself to update a window in the host application (via the extension) every
>> time the script calls print().
>
> Then replace sys.stdout (and maybe also sys.stderr) by another object that
> does what you want whenever its write() method is called.
>
>
>> But I guess that won't work if the script raises an exception...
>
> Yep, you better catch those yourself. The C-API function you use for
> executing the Python code in the first place will tell you when there was
> an error.
>
> BTW, my mention of Cython wasn't just a joke. You might want to look at it
> because it makes these things essentially trivial compared to plain C-API
> code in C.
>
> Stefan
>


OK, I _think_ I'm getting warmer... But I wonder, do I need to create 
new sys.stdout / sys.stderr objects? Can I not simply assign a custom C 
function to the write() methods of the existing sys.stdout / sys.stderr 
objects?