[Python-Dev] Re: Passing floats to "i" parser marker

[Pete Shinners]

i've got a couple observations for this change to ParseTuple.

for my personal extension code, i actually benefit from the features of 
automatic float-to-int conversion. if this is going to change i'll 
indeed be updating my libraries. unfortunately it seems to workaround 
this requires a lot of extra code. simple parsing must now become a set 
of blocks and cases. (no error handling in these examples...)
     PyArg_ParseTuple("is", &x, &text);
becomes
     PyArg_ParseTuple("os", &objx, &text);
     if((tmp=PyNumber_Int(objx))
     {
         x = PyInt_AsLong(tmp);
         Py_DECREF(tmp);
     }

naturally i'll be reducing that block to some function i can call, but 
it adds an extra step of typechecking and error reporting for each 
integer argument in my function. I'd really prefer a method to get the 
current behavior, perhaps "I" in the format string would be a logical 
choice?


in the same context, i'm wondering if the "s" formatting should change 
also? currently you can pass unicode or string objects and they get 
properly converted. i use so little of unicode my input may be totally 
invalid, but it seems float->int is approximate to unicode->string ?
i'm not sure what (if anything) should be done about this, but didn't 
see it mentioned in the thread.


lastly, as a contrived example. to insert an item in the middle of a 
list is pretty simple,
     mylist.insert(len(mylist)/2, myval)
with the new integer division, this would pass a float into an integer 
argment(?). just food for thought, wondering what the expected behaviour 
of this would be?


my coming from a C background makes this float to int conversion pretty 
natural to my mind. but i can see how that doesn't always make it a good 
idea. sorry if my post is not desired, it's my first to python-dev, but 
i've been lurking for a few weeks.