Mailman 3 January 2018 - Python-ideas

make Connections iterable
by Oscar Smith Jan. 9, 2018

Jan. 9, 2018

I am currently working on a program where it would be really useful if a connection had a __next__ method, because then it would be much easier to iterate over. It would just be an alias to recv, but would allow you to do things like merging the results of connections using heapq.merge that currently are highly non-trivial to accomplish. Is there a reason this API isn't supported? Oscar Smith

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Re: [Python-ideas] make Connections iterable
by Amit Green Jan. 9, 2018

Jan. 9, 2018

On Mon, Jan 8, 2018 at 10:34 PM, Nick Coghlan <ncoghlan(a)gmail.com> wrote > It could be useful to include a recipe in the documentation that shows a > generator with suitable error handling (taking the generic connection > errors and adapting them to app specific ones) while also showing how to > adapt the connection to the iterator protocol, though. > Agreed +1. This would be great for three reasons: - Error handling should be as close to the source of errors as possible (i.e.: in the iterator). - Converting error's and adapting them is a great idea; - Mostly: Any documentation that shows people how to do better error handling, is always welcome. <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campai…> Virus-free. www.avast.com <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campai…> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

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Re: [Python-ideas] [Python-Dev] subprocess not escaping "^" on Windows
by Chris Angelico Jan. 8, 2018

Jan. 8, 2018

Redirecting this part of the conversation to python-ideas. On Mon, Jan 8, 2018 at 3:17 AM, Christian Tismer <tismer(a)stackless.com> wrote: > As a side note: In most cases where shell=True is found, people > seem to need evaluation of the PATH variable. To my understanding, > >>>> from subprocess import call >>>> call(("ls",)) > > works in Linux, but (with dir) not in Windows. But that is misleading > because "dir" is a builtin command but "ls" is not. The same holds for > "del" (Windows) and "rm" (Linux). That's exactly what shell=True is for - if you want a shell feature, you use the shell. What exactly would emulate_shell do? Would it simply do a $PATH or %PATH% search, but otherwise function as shell=False? Would it process redirection? Would it handle interpolations? I think not, from your description: > Perhaps it would be a good thing to emulate the builtin programs > in python by some shell=True replacement (emulate_shell=True?) > to match the normal user expectations without using the shell? but it becomes difficult to draw the line. For instance, with emulate_shell=True, what would you do with all the sh/bash built-ins: https://www.gnu.org/software/bash/manual/html_node/Bourne-Shell-Builtins.ht… https://www.gnu.org/software/bash/manual/html_node/Bash-Builtins.html I'm thinking especially of the commands where bash has its own handling of something that could otherwise be found in $PATH, like pwd, time, and echo, but shells can do a lot of other things too. When do you actually want to execute a shell built-in from Python but without using the shell itself? You give the example of ls/dir, but if that ever comes up in real-world code, I'd toss it out and recommend a cross-platform os.listdir or equivalent. There are plenty of times I've wanted a really quick way to redirect a standard stream from Python, but that isn't part of what you're recommending. Can you give a real-world example that would be improved by this? I know this was just a side note in your original, but I'd like to hear more about what would make it useful. ChrisA

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Allow to compile debug extension against release Python in Windows
by Ivan Pozdeev Jan. 7, 2018

Jan. 7, 2018

The Windows version of pyconfig.h has the following construct: if defined(_DEBUG) pragma comment(lib,"python37_d.lib") elif defined(Py_LIMITED_API) pragma comment(lib,"python3.lib") else pragma comment(lib,"python37.lib") endif /* _DEBUG */ which fails the compilation of a debug version of an extension. Making debugging it... difficult. Perhaps we could define some other constant? I'm not sure whether such compilation is a good idea in general, so asking here at first. -- Regards, Ivan

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Add an UML class diagram to the collections.abc module documentation
by Yahya Abou 'Imran Jan. 5, 2018

Jan. 5, 2018

We can find very usefull class diagramm to understand the hierarchy of the builtin Collection abstract class and interface in java. Some examples: http://www.falkhausen.de/Java-8/java.util/Collection-Hierarchy-simple.html http://www.falkhausen.de/Java-8/java.util/Collection-List.html But when I search about python's ABC, The more detailed I can find are those from the book of Luciano Ramalho Fluent Python: https://goo.gl/images/8JGjvM https://goo.gl/images/6xZqcA (I think they're done with pyreverse of pylint) They are fine, but I think we could provide some other more detailed in this page: https://docs.python.org/3/library/collections.abc.html The table could be difficult to understand, a diagram help visualize things. I've began working on it with plantuml and pyreverse, I'm joining to this mail what I've done so far so you can tell me what you think.

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a set of enum.Enum values rather than the construction of bit-sets as the "norm"?
by Paddy3118 Jan. 3, 2018

Jan. 3, 2018

Maybe it is time to deemphasize the creation and passing of what is, in effect, bit-sets <https://en.wikipedia.org/wiki/Bit_array>as a single argument, and instead promote the passing of a set of members of an enum.Enum <https://docs.python.org/3/library/enum.html> constants. Thi comes about because someone wrote a description, (since deleted), of constructing bit-sets to use in passing flags to, for example, the re.compile <https://docs.python.org/3/library/re.html#re.compile>function. The use of individual bits in a bit-array/bit-set to pass multiple flags is an implementation detail. Should we not *first *teach the passing of a set of enum.Enum constant values in one argument as the *pythonic *way; and leave bit-sets and other types of enum's as a performance or interoperability detail? Comments please, (And a happy new year to you :-)

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