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Singleton: How should it be used
...rface widgets
It is supposed to be a cache
In strings
In Sessions
I can go all day long
How to create the best singleton:
The smaller, the better. I am a minimalist
Make sure it is thread safe
Make sure it is never null
Make sure it is created only once
Lazy or system initialization? Up to your re...
Browsers' default CSS for HTML elements
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A GitHub repository of all W3C HTML spec and vendor default CSS stylesheets can be found here
1. Default Styles for Firefox
2. Default Styles for Internet Explorer
3. Default Styles for Chrome / Webkit
4. Default Styles for Opera
5. Default St...
How to avoid null checking in Java?
...ts they are participating in and defensively overcheck for nulls. Additionally, when writing their own code, they tend to rely on returning nulls to indicate something thus requiring the caller to check for nulls.
To put this another way, there are two instances where null checking comes up:
Whe...
Learning Python from Ruby; Differences and Similarities
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[x*x for x in values if x > 15]
to get a new list of the squares of all values greater than 15. In Ruby, you'd have to write the following:
values.select {|v| v > 15}.map {|v| v * v}
The Ruby code doesn't feel as compact. It's also not as efficient since it first converts the values a...
In C++, what is a virtual base class?
..." diagram is confusing, although it seems to be commonly used. This is actually a diagram showing class inheritance relationships -- not an object layout. The confusing part is that if we do use virtual, then the object layout looks like the diamond; and if we do not use virtual then the object la...
Super-simple example of C# observer/observable with delegates
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The observer pattern is usually implemented with events.
Here's an example:
using System;
class Observable
{
public event EventHandler SomethingHappened;
public void DoSomething() =>
SomethingHappened?.Invoke(this, EventArgs.Empt...
Add only non-whitespace changes
I have my text editor to automatically trim trailing whitespace upon saving a file, and I am contributing to an open source project that has severe problems with trailing whitespace.
...
Capture Signature using HTML5 and iPad
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I apologize. I think your documentation is actually adequate. It seemed limited until I realized just how easy this is to use. I got it fully implemented in a form, storing in the database and retrieving back to page in under an hour. I suppose, I was comparing it to libr...
What is recursion and when should I use it?
...sion.
To see why, walk through the steps that the above languages use to call a function:
space is carved out on the stack for the function's arguments and local variables
the function's arguments are copied into this new space
control jumps to the function
the function's code runs
the function's...
Determining if a number is either a multiple of ten or within a particular set of ranges
...rite out the pseudo code, but I'm not entirely sure how to write them logically.
13 Answers
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