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Abstract class in Java
...
If we wish to access a member specific to a particular subclass, we must cast down to that subclass first:
// Say ImplementingClass also contains uniqueMethod()
// To access it, we use a cast to tell the runtime which type the object is
AbstractClass b = new ImplementingClass();
((ImplementingCla...
Python str vs unicode types
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unicode is meant to handle text. Text is a sequence of code points which may be bigger than a single byte. Text can be encoded in a specific encoding to represent the text as raw bytes(e.g. utf-8, latin-1...).
Note that unicode is not encoded! T...
What are some uses of template template parameters?
...ALUE> class interface {
void do_something(VALUE v) {
static_cast<DERIVED*>(this)->do_something(v);
}
};
template <typename VALUE> class derived : public interface<derived, VALUE> {
void do_something(VALUE v) { ... }
};
typedef interface<derived<int...
Load RSA public key from file
...ion when I tried with files I generated with ssh-keygen -t rsa -b 2048 command. With files generated with the commands in the solution it worked.
– Kristóf Dombi
Aug 10 '15 at 18:36
...
How can I add to List
...
You can't (without unsafe casts). You can only read from them.
The problem is that you don't know what exactly the list is a list of. It could be a list of any subclass of Number, so when you try to put an element into it, you don't know that the ele...
How do I safely pass objects, especially STL objects, to and from a DLL?
...iginal_type get() const
{
original_type result;
result = static_cast<original_type>(*data);
return result;
}
void set_from(const original_type& value)
{
data = reinterpret_cast<safe_type*>(pod_helpers::pod_malloc(sizeof(safe_type))); //note the pod_malloc c...
How do I modify fields inside the new PostgreSQL JSON datatype?
...nb manipulation functionality within PostgreSQL itself (but none for json; casts are required to manipulate json values).
Merging 2 (or more) JSON objects (or concatenating arrays):
SELECT jsonb '{"a":1}' || jsonb '{"b":2}', -- will yield jsonb '{"a":1,"b":2}'
jsonb '["a",1]' || jsonb '["b",2...
Why is it slower to iterate over a small string than a small list?
...IIObject *)(op))->state.kind) is (I think) an indirection and a C-level cast);
#define PyUnicode_DATA(op) \
(assert(PyUnicode_Check(op)), \
PyUnicode_IS_COMPACT(op) ? _PyUnicode_COMPACT_DATA(op) : \
_PyUnicode_NONCOMPACT_DATA(op))
(which is also boring for similar reasons, assu...
Exporting functions from a DLL with dllexport
... ::LoadLibrary(T"opengl_plugin.dll");
m_pfnGetEngineVersion = reinterpret_cast<fnGetEngineVersion *>(
::GetProcAddress(m_hDLL, "getEngineVersion")
);
m_pfnRegisterPlugin = reinterpret_cast<fnRegisterPlugin *>(
::GetProcAddress(m_hDLL, "registerPlugin")
);
...
Foreign Key to multiple tables
...
ID int primary key,
Name varchar(50) NOT NULL,
PartyTypeId as cast(2 as tinyint) persisted,
foreign key (ID, PartyTypeId) references Party(PartyId, PartyTypeID)
)
CREATE TABLE dbo.[User]
(
ID int primary key,
Name varchar(50) NOT NULL,
PartyTypeId as cast(1 as tinyint...