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 ...

learn more… | top users | synonyms (1)

0
votes
1answer
118 views

Functional dependencies diagram

I'm searching for the correct type of diagram in which I can see all dependencies between the functions, classes and files of my Python program (multiple files). It's for cleaning purposes. So my ...
-2
votes
1answer
226 views

Base Class, with method that returns Derived Class. design flaw?

I'm writing a Math equation solver in python (for fun). The first design that came to my mind: Expression: base class for every item in an equation (maybe bad name). BinaryExpression extends ...
3
votes
3answers
1k views

Lambda expressions with no parameters in Haskell and / or lambda calculus

In eager languages like Scheme and Python, you can use a lambda expression without parameters to delay evaluation, e.g. in Scheme (Chicken Scheme): #;1> (define (make-thunk x) (lambda () (+ x 1))) ...
0
votes
1answer
70 views

Should instance variables be bound to the instance right in the beginning of the method they are created in?

A common problem for me - and it's not really a problem, but somehow I again and again ask myself, what is the normal way to handle this - is that there is a method and within this method a couple of ...
2
votes
2answers
253 views

Building a string parser for user command and control?

My goal is to build a command parser that has basic syntax and multiple possible branches at each point. These commands come from users of the system and are text input (no GUI). The basic syntax is ...
2
votes
1answer
106 views

Python property best practices [closed]

Is there any situation where it makes sense to define a python property, where getting (not setting) it would raise an exception? I don't think this ever happens for fields in classes, hence the ...
0
votes
3answers
156 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 ...
1
vote
1answer
255 views

writing functional/integration tests for python

I am new to python and functional/integration tests as a whole. I know how to write unit tests, but in this case i do not need isolation for specific functions, rather i need my python script to be ...
3
votes
2answers
240 views

Is a bad practice create database structure on the runtime?

Im creating a crawler app that will always in the beggining, when the Class constructor, ensure that the basic database structure exists. Is this a bad practice? What is the advantage os creating the ...
-1
votes
1answer
197 views

Unevenly distributed random number generation [duplicate]

Let's say I have to generate random number from 1 to 100, however, the probability of each number is not 1/100, but a predefined probability. How to generate that number? I use Ruby/Python.
1
vote
4answers
137 views

Efficient “Object with weights” structure

I need to find an "efficient" data structure / set of algorithms to do the following things: I have a list of objects. I need to assign them weights and later on increase or decrease these weights. ...
0
votes
1answer
208 views

Simple unicode application?

I want to create simple language learning applications to help friends in learning languages. A simple Java console application would do the trick, but the Windows console does not seem to handle ...
0
votes
2answers
136 views

At what point should you start putting functions in a new file? [closed]

I'm currently writing a python script. It's currently about 400 lines long, and it seems like it's getting a bit long, as when I'm trying to scroll through it with eclipse it takes a bit to get from ...
0
votes
1answer
132 views

Should an object query its owner?

I have a World class World: def __init__(self): self.size = 10 self.n_busStops = 10 self.busStopMatrix = SpatialGraph(self.size, self.n_busStops, 1.0) self.buses ...
4
votes
6answers
627 views

Should I store x,y coordinates as an array, a class object, or two variables?

I have a MyObject which has an x and y coordinate. as far as I can see, I can store it in three ways: class MyObject: def __init__(self, x, y): self.x = x self.y = y class ...
15
votes
5answers
7k views

Is it a good practice to declare instance variables as None in a class in Python?

Consider the following class: class Person: def __init__(self, name, age): self.name = name self.age = age My coworkers tend to define it like this: class Person: name = ...
1
vote
2answers
268 views

Is creating and writing to one large file faster than creating and writing to many smaller files in Python on Linux?

If using Python on a Linux machine, which of the following would be faster? Why? Creating a file at the very beginning of the program, writing very large amounts of data (text), closing it, then ...
39
votes
2answers
4k views

How do I move away from the “for-loop” school of thought?

This is a rather conceptual question, but I was hoping I could get some good advice on this. A lot of the programming I do is with (NumPy) arrays; I often have to match items in two or more arrays ...
3
votes
2answers
221 views

Which programming idiom to choose for this open source library?

I have an interesting question about which programming idiom is easier to use for beginner developers writing concrete file parsing classes. I'm developing an open source library, which one of the ...
8
votes
2answers
5k views

Why doesn't Python have a “flatten” function for lists?

Erlang and Ruby both come with functions for flattening arrays. It seems like such a simple and useful tool to add to a language. One could do this: >>> mess = [[1, [2]], 3, [[[4, 5]], 6]] ...
4
votes
4answers
1k views

How does Python compile some its code in C?

I read that some constructs of Python are more efficient because they are compiled in C. https://wiki.python.org/moin/PythonSpeed/PerformanceTips Some of the examples used were map() and filter(). I ...
3
votes
1answer
207 views

What is the right way to process inconsistent data files?

I'm working at a company that uses Excel files to store product data, specifically, test results from products before they are shipped out. There are a few thousand spreadsheets with anywhere from ...
2
votes
2answers
649 views

One boilerplate class or many similar classes?

Lets say I'm trying to model a variety of objects that are virtually identical, the only difference being their class variables. Am I better off creating one boilerplate class and just calling the ...
3
votes
2answers
182 views

Should I use nested matrices or dictionaries?

As per Should I ask my question about which data structure to use here? I'm asking this here. Hopefully this isn't too implementation specific. I'm currently developing a program that will represent ...
0
votes
1answer
67 views

Where to save something between invocations?

The 2nd time I run this program I'd like it to start in the same HDD location as the previous instance. How should I save, or remember, where I was so the program starts in the same place? I'd like ...
1
vote
3answers
266 views

How do I test my code in Python other than by doing it by hand?

I am used to user testing in Java, and I also manually test each section of code I write, but now, I want to automate it. There is no GUI for this project, so user testing is not required and I can ...
0
votes
1answer
227 views

Best Practices For Temporary Scripts (Python)

I am running two separate programs which are similar enough that they share a lot of code. I run these programs often and after I evaluate the output. This is a very fluid process and everytime is ...
0
votes
1answer
211 views

Python case statement? [duplicate]

I made a simple Python script that takes user input in order to generate a series of mathematical responses. In one part I did this: while True: And iterated through the loop until I used an if ...
0
votes
2answers
202 views

How to route messages between clients using a central server in Python

I've got three Raspberry Pis sitting around. I want 2 of them to be able to chat while the 3rd routes the messages (acts as a server between them). The general flow of events should be something like ...
2
votes
1answer
353 views

How do you make decorators as powerful as macros?

Quick background: I am designing a Pythonic language that I want to be as powerful as Lisp while remaining easy to use. And by "powerful", I mean "flexible and expressive". I've just been introduced ...
0
votes
3answers
220 views

How to convert this recursive problem to iterative? Line Simplification algorithm fails to run due to Maximum Recursion Depth being hit

I am implementing the Douglas, Peucker's Line Simplification algorithm in Python. I started with this implementation. However, it fails to run in Python due to Maximum Recursion Depth being hit. How ...
0
votes
1answer
152 views

Running Python script in background on Mac

I have a Python script that counts the number of file in a folder, and if the number of files exceeds 10 then it creates a popup window to ask the user to clean up the folder (I use tkMessageBox). ...
2
votes
1answer
275 views

Is Lambda Still Supported In Python?

Only one or two years ago, I remember reading Python constructs that would be removed from Python -- reduce was one of them -- and other constructs that would be emphasized like comprehensions and ...
1
vote
1answer
173 views

Should I separate a web api from the webserver?

Lets say I'm building a site similar to this or Quora (or some arbitrary blog-like site). I need a real-time component that will be using web-sockets/long-polling to notify the user of new posts, ...
9
votes
5answers
1k views

Are there technical limitations or language features that prevent my Python script from being as fast as an equivalent C++ program?

I'm a long-time Python user. A few years ago, I started learning C++ to see what it could offer in terms of speed. During this time, I would continue to use Python as a tool for prototyping. This, it ...
2
votes
2answers
253 views

Django CBVs vs FBVs

For creating a large Django project with many apps, my first initial thought was to used Class Based Views (as the Django tutorials seem to emphasize). However, I noticed that due to a lot of the ...
3
votes
1answer
297 views

Good practice for returns in Python

I was recently working on some prototype code in Python. The code worked great, then I realized that I needed a little more feedback from one of my functions so I changed the return statement from ...
1
vote
3answers
160 views

the perils of using eval() for dynamic object creation — is this a valid argument in a consenting-adults culture?

I've read on stackoverflow explicit warnings against using eval() to create objects. The reason that seems to be given is that malicious code could be injected and blindly created objects could ...
0
votes
2answers
159 views

Need help understanding a recursion example in Python

Python is my first programming language, and I'm learning it from "How to Think Like a Computer Scientist". In Chapter 5 the author gives the following example on recursion: def factorial(n): if n ...
0
votes
1answer
104 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 ...
8
votes
2answers
360 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 ...
0
votes
1answer
1k views

Javascript function should call python logic in django web development without additional triiger

I have been trying to solve this problem for sometime now. This is regarding django web development. I have an HTML page which has a Javascript function to upload an image file from the users local ...
3
votes
1answer
121 views

optimize human-readable database with index

i need to store a large amount of data - about 10 million entries of the format unique hash (64 chars), value 1 (5 chars), value 2 (9 chars) i will be reading and deleting (but not updating) this ...
5
votes
2answers
943 views

where exactly should python business logic be placed in django

I have just begun to learn Django/Python/Web Development. This problem has been troubling me for a while now. I am creating an application with multiple templates in Django. I have a views.py which ...
0
votes
0answers
28 views

How to deal with multiple output modes of multiple types?

Note: The business domain being a bit complicated to explain, I replaced the names of actual classes by more illustrative examples. I'm writing an application in which the business layer returns a ...
2
votes
2answers
84 views

subclass reference to another subclass

Imagine I have the following code: class A: pass class B(A): pass class C(A): def __init__(self): self.b = B() Is the above code correct in terms of correct inheritance? I ...
0
votes
0answers
46 views

Defining property and find substitution for copy function of python in cython

I want to cythonize a code in python to speed up the code. In the following you can see my attempt to make my python class understandable for cython: import numpy as np cimport numpy as np ctypedef ...
2
votes
1answer
109 views

Python API: Extension Module or Pure Module

We have a C++ application, with C++ interfaces changing regularly during development. We also have a C API which is designed to be stable in spite of such changes; the C API is tighly focused on ...
1
vote
1answer
94 views

Adding new functionality to all of shelve.Shelf's subclasses in Python

In order to avoid the overhead associated with the shelve module's writeback option I'm interested in putting together a shelf class that only accepts hashable values, with hashability being a proxy ...
1
vote
2answers
331 views

Can a version of Python's shelve module that knows when its entries have been modified be written in any programming language?

shelve is a Python module that makes it easy to persist a Python dictionary to disk (under the right conditions). The documentation for shelve gives this example to demonstrate one of the pitfalls of ...