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Checking for empty queryset in Django
...is the code I refer to is only an example that it contains a line if not my_objects: to demonstrate that this is how they do it in the docs. All else is utterly irrelevant so I do not get your point. They could as well make a thousand queries and it would still be totally irrelevant as this is not t...
static constructors in C++? I need to initialize private static objects
...t ordinary class.
class StaticStuff
{
std::vector<char> letters_;
public:
StaticStuff()
{
for (char c = 'a'; c <= 'z'; c++)
letters_.push_back(c);
}
// provide some way to get at letters_
};
class Elsewhere
{
static StaticStuff staticSt...
How to implement an STL-style iterator and avoid common pitfalls?
... void swap(iterator& lhs, iterator& rhs); //C++11 I think
};
input_iterator : public virtual iterator {
iterator operator++(int); //postfix increment
value_type operator*() const;
pointer operator->() const;
friend bool operator==(const iterator&, const iterator&)...
Get the first element of each tuple in a list in Python [duplicate]
...
Use a list comprehension:
res_list = [x[0] for x in rows]
Below is a demonstration:
>>> rows = [(1, 2), (3, 4), (5, 6)]
>>> [x[0] for x in rows]
[1, 3, 5]
>>>
Alternately, you could use unpacking instead of x[0]:
res_li...
Differences between “java -cp” and “java -jar”?
What is the difference between running a Java application with java -cp CLASSPATH and java -jar JAR_FILE_PATH ? Is one of them preferred to the other for running a Java application? I mean which one of these ways is more expensive for JVM (according to their machine resources usage)?
...
Maven: add a dependency to a jar by relative path
...ging=<myPackaging> -DlocalRepositoryPath=<path>
Update: It appears that install:install-file ignores the localRepositoryPath when using the version 2.2 of the plugin. However, it works with version 2.3 and later of the plugin. So use the fully qualified name of the plugin to specify ...
How to check if one DateTime is greater than the other in C#
...s all my unit tests:
public DateTime Start
{
get { return _start; }
set
{
if (_end.Equals(DateTime.MinValue))
{
_start = value;
}
else if (value.Date < _end.Date)
{
_start ...
How do you add a Dictionary of items into another Dictionary
...
@animal_chin Because we have to implement half of the language ourselves? Yes. Impressed. Don't get me wrong I love operator overloading. I just don't love having to use it for basic features that should be built in.
...
Apache Spark: The number of cores vs. the number of executors
...s a little more concrete, here’s a worked example of configuring a Spark app to use as much of the cluster as
possible: Imagine a cluster with six nodes running NodeManagers, each
equipped with 16 cores and 64GB of memory. The NodeManager capacities,
yarn.nodemanager.resource.memory-mb and
yarn.no...
How to specify different Debug/Release output directories in QMake .pro file
...cpp \
src/dialogs.cpp
Release:DESTDIR = release
Release:OBJECTS_DIR = release/.obj
Release:MOC_DIR = release/.moc
Release:RCC_DIR = release/.rcc
Release:UI_DIR = release/.ui
Debug:DESTDIR = debug
Debug:OBJECTS_DIR = debug/.obj
Debug:MOC_DIR = debug/.moc
Debug:RCC_DIR = debug/.rcc
Debug:...