Mailman 3 September 2012 - Python-ideas

Re: [Python-ideas] issue15824
by Ben Toews Sept. 10, 2012

Sept. 10, 2012

Hello, We have been discussing the value of having namedtuple as the return type for urlparse.urlparse and urlparse.urlsplit. See that thread here: http://bugs.python.org/issue15824 . I jumped the gun and submitted a patch without seeing if anyone else thought different behavior was desirable. My argument is that it would be a major usability improvement if the return type supported item assignment. Currently, something like the following is necessary in order to parse, make changes, and … [View More]

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Re: [Python-ideas] reprs of recursive datastructures.
by Guido van Rossum Sept. 9, 2012

Sept. 9, 2012

On Sat, Sep 8, 2012 at 9:17 AM, Terry Reedy <tjreedy(a)udel.edu> wrote: > On 9/8/2012 2:27 AM, Guido van Rossum wrote: >> Can someone explain what problem we are trying to solve? I fail to >> uderstand what's wrong with the current behavior... > Pairs of different things have the same representation, making the > representation ambiguous to both people and the interpreter. Well yeah, when designing a repr() we usually have to compromise. E.g. if you render a class … [View More]

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reprs of recursive datastructures.
by Mike Graham Sept. 8, 2012

Sept. 8, 2012

With the Python 3 loosening of where ... can occur, this somewhat suboptimal behaviour occurs >>> x = [] >>> x.append(x) >>> x [[...]] >>> eval(repr(x)) [[Ellipsis]] Is this something that can be improved? Is it something worth improving? Mike

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Add annotations to global statement
by Alexandre Bosc Sept. 6, 2012

Sept. 6, 2012

I think the annotations of parameters and return value of a function, a useful practice for the user of the function. As a function can modify or create global variables, and as it's important for the end user, I would appreciate to add annotations in the global statement. An annotation syntax similar to that of parameters could be employed : global var : expression global var1 : expression1, var2 : expression2,... cheers, Alex (geoscience modeler)

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Memoryview tolist() method is misleading
by Alexander Belopolsky Sept. 3, 2012

Sept. 3, 2012

Consider this: >>> memoryview(b'x').cast('B', ()).tolist() 120 The return value of to list() is an int, not a list. I suggest to deprecate memoryview.tolist() and .tobytes() methods (soft deprecation - in documentation only) and recommend using list(m) and bytes(m) instead. For the multidimensional (and 0-dimensional) views, I suggest adding an unpack([depth]) method that would unpack a view into a nested list of tuples or subviews. For example a single-byte scalar should unpack … [View More]

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itertools.chunks(iterable, size, fill=None)
by anatoly techtonik Sept. 3, 2012

Sept. 3, 2012

Now that Python 3 is all about iterators (which is a user killer feature for Python according to StackOverflow - http://stackoverflow.com/questions/tagged/python) would it be nice to introduce more first class functions to work with them? One function to be exact to split string into chunks. itertools.chunks(iterable, size, fill=None) Which is the 33th most voted Python question on SO - http://stackoverflow.com/questions/312443/how-do-you-split-a-list-into-even… P.S. CC'ing to python-… [View More]

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sequence.apply(function)
by anatoly techtonik Sept. 2, 2012

Sept. 2, 2012

Idea: Apply function to every element of a sequence and return new sequence. It's more pythonic than map(), because clearly works only as a list method. -- anatoly t.

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Verbose traceback formatting
by Mike Graham Sept. 1, 2012

Sept. 1, 2012

It's possible to give a lot more on error than the default traceback gives you. I propose that Python should ship a more verbose formatter and a command line switch to use it. Here's an example of IPython's verbose formatter. I wrote a buggy program: > def f(a): > x = a * 4 > y = a - 4 > return x / y > > def main(): > for i in xrange(100): > f(i) > > main() and then ran it in IPython with verbose tracebacks and got the following output: … [View More]

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Add a "hasmethod()" builtin?
by Guido van Rossum Sept. 1, 2012

Sept. 1, 2012

There's a concept that's sometimes useful when explaining behavior of certain Python operations in terms of simpler ones, and it is "does the class of x define a method m?". This currently cannot expressed using hasattr(): hasattr(x, 'm') might find an instance variable named m, but that is not a method (and there are contexts where they are not interchangeable); hasattr(type(x), 'm') might find a *metaclass* method. Example of the former (assume Python 3): class C: def __add__(self, other)… [View More]

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Unpack of sequences
by Carlo Pires Sept. 1, 2012

Sept. 1, 2012

Hi, I was just wondering why unpack of sequences did not follow same behavior of functions parameters. I mean: first, *rest = 'a b c'.split() should work in python, why doesn't it? -- Carlo Pires

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