No error , No gain

While using new_list = my_list, any modifications to new_list changes my_list every time. Why is this, and how can I clone or copy the list to prevent it? With new_list = my_list, you don't actually have two lists. The assignment just copies the reference to the list, not the actual list, so both new_list and my_list refer to the same list after the assignment. To actually copy the list, you hav..

I wanted to create a list of options for testing purposes. At first, I did this: ArrayList places = new ArrayList(); places.add("Buenos Aires"); places.add("Córdoba"); places.add("La Plata"); Then, I refactored the code as follows: ArrayList places = new ArrayList( Arrays.asList("Buenos Aires", "Córdoba", "La Plata")); Is there a better way to do this? It would be simpler if you were to just dec..

How can I make two decorators in Python that would do the following? @makebold @makeitalic def say(): return "Hello" ...which should return: "Hello" I'm not trying to make HTML this way in a real application - just trying to understand how decorators and decorator chaining works. If you are not into long explanations, see Paolo Bergantino’s answer. Decorator Basics Python’s functions are objects..

I'm using this code to get standard output from an external program: >>> from subprocess import * >>> command_stdout = Popen(['ls', '-l'], stdout=PIPE).communicate()[0] The communicate() method returns an array of bytes: >>> command_stdout b'total 0\n-rw-rw-r-- 1 thomas thomas 0 Mar 3 07:03 file1\n-rw-rw-r-- 1 thomas thomas 0 Mar 3 07:03 file2\n' However, I'd like to work with the output as a no..

How do I copy a file in Python? I couldn't find anything under os. shutil has many methods you can use. One of which is: from shutil import copyfile copyfile(src, dst) # 2nd option copy(src, dst) # dst can be a folder; use copy2() to preserve timestamp Copy the contents of the file named src to a file named dst. Both src and dst need to be the entire filename of the files, including path. The de..

How do I unit test (using xUnit) a class that has internal private methods, fields or nested classes? Or a function that is made private by having internal linkage (static in C/C++) or is in a private (anonymous) namespace? It seems bad to change the access modifier for a method or function just to be able to run a test. Update: Some 10 years later perhaps the best way to test a private method, ..

This question's answers are a community effort. Edit existing answers to improve this post. It is not currently accepting new answers or interactions. For example, if passed the following: a = [] How do I check to see if a is empty? if not a: print("List is empty") Using the implicit booleanness of the empty list is quite pythonic. Patrick The pythonic way to do it is from the PEP 8 style guide ..

I have an Activity in Android, with two elements: EditText ListView When my Activity starts, the EditText immediately has input focus (flashing cursor). I don't want any control to have input focus at startup. I tried: EditText.setSelected(false); EditText.setFocusable(false); No luck. How can I convince the EditText to not select itself when the Activity starts? Excellent answers from Luc and M..

I want to disable the resizable property of a textarea. Currently, I can resize a textarea by clicking on the bottom right corner of the textarea and dragging the mouse. How can I disable this? The following CSS rule disables resizing behavior for textarea elements: textarea { resize: none; } To disable it for some (but not all) textareas, there are a couple of options. You can use class attribu..

This question's answers are a community effort. Edit existing answers to improve this post. It is not currently accepting new answers or interactions. What's the difference between the list methods append() and extend()? append: Appends object at the end. x = [1, 2, 3] x.append([4, 5]) print(x) gives you: [1, 2, 3, [4, 5]] extend: Extends list by appending elements from the iterable. x = [1, 2, ..