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Regular cast vs. static_cast vs. dynamic_cast [duplicate]
... pointer if the object referred to doesn't contain the type casted to as a base class (when you cast to a reference, a bad_cast exception is thrown in that case).
if (JumpStm *j = dynamic_cast<JumpStm*>(&stm)) {
...
} else if (ExprStm *e = dynamic_cast<ExprStm*>(&stm)) {
......
Creating a singleton in Python
... would recommend Method #2, but you're better off using a metaclass than a base class. Here is a sample implementation:
class Singleton(type):
_instances = {}
def __call__(cls, *args, **kwargs):
if cls not in cls._instances:
cls._instances[cls] = super(Singleton, cls).__c...
Get Base64 encode file-data from Input Form
...ipt.
The easy way:
The readAsDataURL() method might already encode it as base64 for you. You'll probably need to strip out the beginning stuff (up to the first ,), but that's no biggie. This would take all the fun out though.
The hard way:
If you want to try it the hard way (or it doesn't work),...
How can I see the SQL that will be generated by a given ActiveRecord query in Ruby on Rails
... solution.
The method is construct_finder_sql(options) (lib/active_record/base.rb:1681) you will have to use send because it is private.
Edit: construct_finder_sql was removed in Rails 5.1.0.beta1.
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Is there a way to instantiate objects from a string holding their class name?
I have a file: Base.h
9 Answers
9
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Finding a branch point with Git?
... two. How can I find the commit in my repository when branch A was created based on master?
22 Answers
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How can I get the full/absolute URL (with domain) in Django?
...n your INSTALLED_APPS, it won't hit the DB at all, and provide information based on the Request object (see get_current_site)
– Darb
Jan 31 '12 at 10:04
...
Java time-based map/cache with expiring keys [closed]
Do any of you know of a Java Map or similar standard data store that automatically purges entries after a given timeout? This means aging, where the old expired entries “age-out” automatically.
...
Difference between HashMap, LinkedHashMap and TreeMap
...e entries were put into the map
"Hashtable" is the generic name for hash-based maps. In the context of the Java API,
Hashtable is an obsolete class from the days of Java 1.1 before the collections framework existed. It should not be used anymore, because its API is cluttered with obsolete methods ...
Why don't structs support inheritance?
...ings happen, as can be seen in C++.
Consider this pseudo-C# code:
struct Base
{
public int A;
}
struct Derived : Base
{
public int B;
}
void Square(Base[] values)
{
for (int i = 0; i < values.Length; ++i)
values [i].A *= 2;
}
Derived[] v = new Derived[2];
Square (v);
By nor...