Python is a dynamic, high-level language. Its design focuses on clear syntax, an intuitive approach to object-oriented programming, and making the right way to do things obvious. Python supports modules, exceptions, had an extensive standard module library. Python can also be embedded in other ...

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1
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1answer
307 views

Watching file changes/additions/removal, but with an eye on partial transfer

I would like to monitor the filesystem in python, so that my application gets warned of the new file addition, file removal, or file change. Once the file is detected, the application starts ...
2
votes
0answers
49 views

auto update strategy for a software distributed as a tar ball written in python 2.7 targeting mac osx

This is what I have planned as an auto update strategy for a software that is as a tar ball. The application is running as a system daemon which means it have root privilege. App runs on startup ...
1
vote
2answers
141 views

Python: Object initialised inside a Class?

Is possible and, if so, common practice to initialize an object inside a class in Python? self.field = Class()
3
votes
1answer
129 views

Seeking Guidance on Thread Safe Scripting

I am trying to write a script that will take multiple paths to files on various servers, search them all simultaneously, and return a single list of results to a user. Initially, I was just using ...
15
votes
4answers
6k views

Why doesn't Python allow multi-line lambdas?

Can someone explain the concrete reasons why BDFL choose to make Python lambdas single line? This is good: lambda x: x**x This results in an error: lambda x: x**x I understand that making ...
1
vote
2answers
54 views

How to handle configuration of Python modules, especially when used standalone and in frameworks like Django

I am trying to package a Python module for pip, following the guide here. One area I would like feedback on is best practices or convention for making my module configurable. The module is a library ...
8
votes
4answers
3k views

Google App Engine, what are the advantages and limitations?

First, does anyone know a specific advantage of Google App Engine for Python Apps? Is there some advantage over Heruko or Appfog? And about the database API? Now, what about the limitations? Are ...
18
votes
3answers
9k views

What is the name of ** in python?

When programming Python I sometimes do a ** to make a conversion. I understand what it does but what data structures am I manipulating? A dict and what is the other? An array? Is there a name for the ...
0
votes
1answer
58 views

how python updates references to variables

For this while loop below. It is clear how the v1,v2,v3 are updated to new data objects based on the equation. But I do not understand how u1,u2,u3 retains the original values of v1,v2,v3.Can someone ...
1
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0answers
71 views

how to test a generator with unittest?

I have programmed a small iterator in Python: class anything(): def __init__(self): self.i=1 def __iter__(self): return self def next(self): if self.i>100: ...
4
votes
2answers
2k views

Every function is a closure?

Wikipedia says, that closure - is a function, which has an access to variables, declared outside of the function. There is even an example: function startAt(x) function incrementBy(y) ...
7
votes
6answers
3k views

What is the simplest human readable configuration file format? [closed]

Current configuration file is as follows: mainwindow.title = 'test' mainwindow.position.x = 100 mainwindow.position.y = 200 mainwindow.button.label = 'apply' mainwindow.button.size.x = 100 ...
0
votes
1answer
90 views

Handling the process of large-scale lists [closed]

What are the efficient ways to process huge lists (+10 millions), and things to consider while manipulating huge lists. First question, when should I use recursion, and when I shouldn't. In both ...
0
votes
4answers
3k views

Using Django without a database [closed]

Is Django a good solution for creating applications that won't use any database and communicate only through an internal API?
40
votes
12answers
5k views

Is C# development effectively inseparable from the IDE you use?

I'm a Python programmer learning C# who is trying to stop worrying and just love C# for what it is, rather than constantly comparing it back to Python. I'm caught up on one point: the lack of ...
1
vote
1answer
50 views

Is this type of data insertion safe and can stop sql injection in Python?

I am learning Database connection from MySQL Connector/Python Developer Guide. This is the code I am using to insert data: conn = mysql.connector.connect(user="user", password="password", ...
0
votes
1answer
119 views

How do different technologies connect to form a web stack? [closed]

I am a little confused, is it possible to implement a front end using common languages like html, css and javascript and then do server side processing using a language of your choice, say python or ...
1
vote
1answer
116 views

Why is a python package more perfomant as zip?

I have read the following text in the setuptools documentation: For maximum performance, Python packages are best installed as zip files. ...
1
vote
2answers
380 views

Is it safe to catch ImportError when trying to import optional modules?

I usually see this pattern at least once in every Python project I work on. For example, in a Django project, this is often added at the bottom of the base settings file: try: from .local_settings ...
4
votes
3answers
243 views

Python - defining exit method before importing

This breaks nothing (in my experience), but lots of things "don't break anything" and are still wrong. #! /usr/bin/env python """Short description of this module.""" def ...
1
vote
0answers
113 views

The Python module-as-singleton hack

I've seen (and once used) this idiom a few times in Python: # At the end of a module: if __name__ == '__main__': main() # or whatever your entry point looks like, this line isn't important else: ...
3
votes
1answer
382 views

Using naming conventions to make `import *` safer in Python

Consider the following code: a.py import os def print_rand(): print os.urandom() And another module: b.py from a import * In this code, I end up with an os variable getting imported from ...
0
votes
1answer
242 views

Is there a canonical way to cache instance methods in python?

I have some computationally intensive functions in my python script that I would like to cache. I went looking for solutions on stack overflow and found lots of links: ...
19
votes
3answers
2k views

Should I pass in filenames to be opened, or open files?

Suppose I have a function that does things with a text file - for example reads from it and removes the word 'a'. I could either pass it a filename and handle the opening/closing in the function, or ...
4
votes
2answers
182 views

In Python, is there any difference (apart from a few listed exceptions) between classes and dictionaries?

My logic goes like this: def A(val): return {'a':val} print(A(7)['a']) is the same as class A: def __init__(self, val): self.a = val print(A(7).a) Obviously, there are problems ...
0
votes
2answers
111 views

Print Statements Inside Function Or Before Calling It? [closed]

I have a script which different people may use. I have print statements so people can follow along what the script is doing, and if it breaks where it went wrong, and if a certain step takes a long ...
8
votes
2answers
343 views

Why don't Python and Ruby make a distinction between declaring and assigning a value to variables?

Two of the most popular dynamically typed scripting languages, Python and Ruby, do not make a distinction in syntax between the declaration of a variable and assignation of a value to it. That is in ...
2
votes
2answers
2k views

Python multiple inheritance or decorators for composable behaviours

I recently discovered (or rather realised how to use) Python's multiple inheritance, and am afraid I'm now using it in cases where it's not a good fit. I want to have some starting data source ...
2
votes
0answers
53 views

How should private dependency links be handled in setup.py

At work we use a private pypi server. This pypi server is specified as a dependency link: ... from setuptools import setup config = ConfigParser.ConfigParser() rc = ...
0
votes
3answers
122 views

OOP: relying on protected properties in a class-subclass contract

I'm coding in Python, but the question seems independent of programming language. I have a class that represents some system check: class Check: @abstractmethod def run() """ You have to ...
1
vote
1answer
91 views

graph implementation in PYthon

I have found the following implementation of a Flow algorithm in Python: class Edge(object): def __init__(self, u, v, w): self.source = u self.sink = v self.capacity = w ...
1
vote
2answers
261 views

How-To: a browser based, real time, shared memory inspection/debugger application [closed]

Background: I have a C application running under Linux utilizing shared memory. I also have a debugger written in Python that can link to said shared memory and access individual variable values of ...
-3
votes
1answer
84 views

Understanding searching through dicts in python [closed]

I'm trying to understand the differences between dict, dict.items and dict.iteritems. I know that items returns a list of all the items, while iteritems returns an iterator, which for large lists can ...
0
votes
1answer
65 views

No repeated coordinates in random walker ensemble

i'm simulating an ensemble of random walkers in 2D in python, I set [x,y] coordinates of my walkers to be gaussian in a 2D grid, then use a rand array of -1 and +1 to move up down left right: N=20 ...
2
votes
2answers
160 views

How much should I break up my unit tests?

I recently learned about unit tests and TDD and have started going back to add unit tests to my code (and thank god, it's proven that some things I've written are much more broken than I thought). ...
1
vote
1answer
207 views

Should I couple these classes?

I am programming in Python. I have several complicated/hard-to-understand XML files that describe the structure of an election. I am trying to write a python wrapper that makes it easy to access this ...
0
votes
1answer
37 views

Plugins and exporting an API between python scripts

I've got a python script, which should read a subdirectory and make all the scripts within it callable like this: python mainscript.py subscript arguments I've figured out most of the details but ...
1
vote
1answer
135 views

Transferring information between a web server and a Python backend?

I have been Googling my problem but haven't been able to come up with anything; here's the situation: I have a PHP / MySQL website hosted with 1and1.com. I also have a Python program that runs on a ...
16
votes
8answers
1k views

Python Coding standards vs. productivity

I work for a large humanitarian organisation, on a project building software that could help save lives in emergencies by speeding up the distribution of food. Many NGOs desperately need our software ...
3
votes
0answers
81 views

Breaking a table over multiple lines in Sphinx

Lets say I have the following function with a docstring: def foo(*args): """ do some fooness +----------------------------+----------------------------------------------------+ | ...
4
votes
4answers
718 views

How to rotate an array of bits

I currently have a PIL Image object which I store as an array of bits (1's and 0's). However I now would like to be able to rotate that image 45 degrees. One way to do it is take the original PIL ...
2
votes
1answer
148 views

What exactly is this Python statement doing?

I'm trying to port a very basic dual contouring algorithm written in Python (here) to C++. I'm not a Python programmer so some of the language syntax is a bit foreign to me. Specifically, this block ...
-3
votes
2answers
56 views

How to perform deferred tasks in backend [closed]

Actually the problem is very common. Let me describe this by example. Imagine you have a web service where users register and pay for some gold status. There is expiration date. The question is how to ...
1
vote
4answers
783 views

How to clean up nested try/except/else?

When writing code, I often want to do something like this: try: foo() except FooError: handle_foo() else: try: bar() except BarError: handle_bar() else: ...
0
votes
3answers
155 views

Is this a pattern: stand-alone classes

Having recently discovered python, I attempted to write a simple logger. Data is read from a device, processes, displayed and stored on disc. Those different tasks belong to different modules, of ...
0
votes
1answer
186 views

Is there a way to prevent variables from changing their type in Python?

It is useful to have the interpreter derive the type of a variable automatically. This on its own is similar to the auto keyword in C++11. However, in Python variables can change their type after ...
1
vote
2answers
172 views

Is using os.environ to store the value of command line switches pythonic?

I write CLI-executable Python 3 scripts regularly to do data compilation and some maintenance tasks, and try to adhere to PEP 8 and the Google Python Style Guide when doing so. Google's guide says to ...
0
votes
1answer
97 views

Checking that a function is only run from __main__ in Python

I often end up with code files that can either be imported or run as __main__. It's easy to handle this by checking if __name__ == '__main__'. But sometimes if my main function gets too big I split ...
0
votes
0answers
35 views

Advice on which approach to follow for sandboxing the input in an intentional “vulnerable” web app (sandbox in python) [duplicate]

my question is about which is the best approach/practice on building a "sandbox mechanism" in Python in a web application. The app will provide intentional vulnerable scenarios, and the user has to ...
13
votes
4answers
4k views

Best practices for execution of untrusted code

I have a project where I need to allow users to run arbitrary, untrusted python code (a bit like this) against my server. I'm fairly new to python and I'd like to avoid making any mistakes that ...