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Why should the “PIMPL” idiom be used? [duplicate]
...
Well, I wouldn't use it. I have a better alternative:
foo.h:
class Foo {
public:
virtual ~Foo() { }
virtual void someMethod() = 0;
// This "replaces" the constructor
static Foo *create();
}
foo.cpp:
namespace {
class FooImpl: virtual public Foo {
pu...
How to disable an input type=text?
...
document.getElementById('foo').disabled = true;
or
document.getElementById('foo').readOnly = true;
Note that readOnly should be in camelCase to work correctly in Firefox (magic).
Demo: https://jsfiddle.net/L96svw3c/ -- somewhat explains the dif...
How do you specify a byte literal in Java?
...it quacks like a duck, I call it a duck.
What you can't do is this:
void foo(byte a) {
...
}
foo( 0xa ); // will not compile
You have to cast as follows:
foo( (byte) 0xa );
But keep in mind that these will all compile, and they are using "byte literals":
void foo(byte a) {
...
}
...
What is a NullPointerException, and how do I fix it?
...example, doSomething() could be written as:
/**
* @param obj An optional foo for ____. May be null, in which case
* the result will be ____.
*/
public void doSomething(SomeObject obj) {
if(obj == null) {
//do something
} else {
//do something else
}
}
Finally, How ...
What's the point of const pointers?
...u're doing things you didn't mean to do. Imagine the following typo:
void foo(int* ptr)
{
ptr = 0;// oops, I meant *ptr = 0
}
If you use int* const, this would generate a compiler error because you're changing the value to ptr. Adding restrictions via syntax is a good thing in general. Just d...
What does a double * (splat) operator do
... arguments. It returns a Hash with key / value pairs.
For this code:
def foo(a, *b, **c)
[a, b, c]
end
Here's a demo:
> foo 10
=> [10, [], {}]
> foo 10, 20, 30
=> [10, [20, 30], {}]
> foo 10, 20, 30, d: 40, e: 50
=> [10, [20, 30], {:d=>40, :e=>50}]
> foo 10, d: 40, ...
Using boolean values in C
... should generally be avoided. Consider a function defined like this
void foo(bool option) { ... }
Within the body of the function, it is very clear what the argument means since it has a convenient, and hopefully meaningful, name. But, the call sites look like
foo(TRUE);
foo(FALSE):
Here, it...
What's the difference between an element and a node in XML?
...rt of the DOM tree, an Element is a particular type of Node
e.g.
<foo> This is Text </foo>
You have a foo Element, (which is also a Node, as Element inherits from Node) and a Text Node 'This is Text', that is a child of the foo Element/Node
...
What is the best way to implement nested dictionaries?
...f you insist on getting this behavior, here's how to shoot yourself in the foot:
Implement __missing__ on a dict subclass to set and return a new instance.
This approach has been available (and documented) since Python 2.5, and (particularly valuable to me) it pretty prints just like a normal dict, ...
How can I create a copy of an object in Python?
...tainer.
list.copy is a shallow copy:
>>> list_of_dict_of_set = [{'foo': set('abc')}]
>>> lodos_copy = list_of_dict_of_set.copy()
>>> lodos_copy[0]['foo'].pop()
'c'
>>> lodos_copy
[{'foo': {'b', 'a'}}]
>>> list_of_dict_of_set
[{'foo': {'b', 'a'}}]
You don...