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Why is “if not someobj:” better than “if someobj == None:” in Python?
...
In the first test, Python try to convert the object to a bool value if it is not already one. Roughly, we are asking the object : are you meaningful or not ? This is done using the following algorithm :
If the object has a __nonzero__ special method (as do...
Disable migrations when running unit tests in Django 1.7
...(self, item):
return None
TESTS_IN_PROGRESS = False
if 'test' in sys.argv[1:] or 'jenkins' in sys.argv[1:]:
logging.disable(logging.CRITICAL)
PASSWORD_HASHERS = (
'django.contrib.auth.hashers.MD5PasswordHasher',
)
DEBUG = False
TEMPLATE_DEBUG = False
TESTS_I...
How to export DataTable to Excel
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Try simple code, to convert DataTable to excel file as csv:
var lines = new List<string>();
string[] columnNames = dataTable.Columns
.Cast<DataColumn>()
.Select(column => column.ColumnName)
.ToArray();
var header = ...
Understanding implicit in Scala
...
In scala implicit works as:
Converter
Parameter value injector
Extension method
There are 3 types of use of Implicit
Implicitly type conversion : It converts the error producing assignment into intended type
val x :String = "1"
val y:Int = x
String...
Algorithm to get the excel-like column name of a number
I'm working on a script that generate some Excel documents and I need to convert a number into its column name equivalent. For example:
...
postgresql - sql - count of `true` values
...his works:
SELECT count(*) AS total
, sum(myCol::int) AS countTrue --convert Boolean to Integer
FROM yourTable
;
or better (to avoid :: and use standard SQL syntax):
SELECT count(*) AS total
, sum(CAST(myCol AS int)) AS countTrue --convert Boolean to Integer
FROM yourTable
;
...
Type converting slices of interfaces
I'm curious why Go does't implicitly convert []T to []interface{} when it will implicitly convert T to interface{} . Is there something non-trivial about this conversion that I'm missing?
...
How to properly check if std::function is empty in C++11?
... an empty lambda doesn't really make sense. Behind the scenes the compiler converts a lambda expression into a struct (or class) definition, with the variables you capture stored as data members of this struct. A public function call operator is also defined, which is what allows you to invoke the l...
Default template arguments for function templates
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On Windows, with all versions of Visual Studio you can convert this error (C4519) to a warning or disable it like so:
#ifdef _MSC_VER
#pragma warning(1 : 4519) // convert error C4519 to warning
// #pragma warning(disable : 4519) // disable error C4519
#endif
See more details ...
Open and write data to text file using Bash?
...x number of file descriptors the kernel can allocate can be found in /proc/sys/file-max or /proc/sys/fs/file-max but using any fd above 9 is dangerous as it could conflict with fd's used by the shell internally. So don't bother and only use fd's 0-9. If you need more the 9 file descriptors in a bash...