etl/docs/raw/patterns/Singleton Base.txt
2026-04-05 14:00:30 +01:00

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Singleton Base
Allows creation of a singleton base class.
etl::singleton_base<typename T>
T The type to use as a singleton.
The class derived derived from this must call the constructor with the instance of itself.
Mutiple call to the constructor will result in an etl::singleton_base_already_created assertion.
Before the constructor Is called, the singleton is in the invalid state.
See also etl::singleton
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Static functions
static T& instance()
Returns a reference to the one instance of T.
Asserts an etl::singleton_base_not_created if the instance has not been attached.
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static bool is_valid()
Returns true if the instance is has been attached, otherwise false.
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Example
class MyType : public etl::singleton_base<MyType>
{
MyType()
: etl::singleton_base<MyType>(*this)
{
}
};
bool is_valid;
is_valid = MyType::is_valid(); // true
MyType& mt = MyType::instance(); // Get the instance