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Java: how do I get a class literal from a generic type?
... String.class denotes the Class
object that represents the type
String and is identical to the
Class object that is returned when
method getClass is invoked on a
String object. A class literal can
be used for runtime type checks and
for reflection.
Parameterized types lose their ...
How to get the original value of an attribute in Rails
...ibute will give you the previous value.
For rails 5.1+
Copied from Lucas Andrade's answer below: https://stackoverflow.com/a/50973808/9359123
Appending _was is deprecated in rails 5.1, now you should append _before_last_save
Something like:
before_save object
do_something_with object.name_...
Makefile variable as prerequisite
...
This will cause a fatal error if ENV is undefined and something needs it (in GNUMake, anyway).
.PHONY: deploy check-env
deploy: check-env
...
other-thing-that-needs-env: check-env
...
check-env:
ifndef ENV
$(error ENV is undefined)
endif
(Note that ifndef and endif...
STL or Qt containers?
What are the pros and cons of using Qt containers ( QMap , QVector , etc.) over their STL equivalent?
14 Answers
...
How does lock work exactly?
...// body
}
finally
{
Monitor.Exit(temp);
}
In C# 4.0 this has changed and it is now generated as follows:
bool lockWasTaken = false;
var temp = obj;
try
{
Monitor.Enter(temp, ref lockWasTaken);
// body
}
finally
{
if (lockWasTaken)
{
Monitor.Exit(temp);
}
}
You c...
How to use Class in Java?
There's a good discussion of Generics and what they really do behind the scenes over at this question , so we all know that Vector<int[]> is a vector of integer arrays, and HashTable<String, Person> is a table of whose keys are strings and values Person s.
However, what stumps me ...
How do I scroll to an element within an overflowed Div?
... that can only show 5 at a time. What is a good way to scroll to item #10, and then item #20? I know the height of all the items.
...
Python ValueError: too many values to unpack [duplicate]
...
self.materials is a dict and by default you are iterating over just the keys (which are strings).
Since self.materials has more than two keys*, they can't be unpacked into the tuple "k, m", hence the ValueError exception is raised.
In Python 2.x, t...
What does AngularJS do better than jQuery? [closed]
I have mainly been using the jQuery library and have just started using AngularJS. I have read a few tutorials on how to use Angular, but I am not clear on why or when to use it, or what benefits I may find in comparison to just using jQuery.
...
Getting time elapsed in Objective-C
...e time elapsed between two events, for example, the appearance of a UIView and the user's first reaction.
7 Answers
...