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@ -6,17 +6,42 @@ template <class Signature> |
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class cFunctionRef; |
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/** A light-weight, type-erased reference to a function object.
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This is similar to a std::function but doesn't copy the function object |
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which means that mutable function objects will be modified for the caller |
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but would not be if using a std::function (See #3990 for implications of this). |
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A cFunctionRef has no empty state but is non-owning and so is safe to call |
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as long as the referred object is still alive. */ |
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### Usage |
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`cFunctionRef` is used whenever you call a normal function with a lambda. e.g. |
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one of the `cWorld::DoWith` functions, |
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m_World->DoWithChunkAt(BlockPos, [](cChunk & a_Chunk) -> bool |
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{ |
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... |
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} |
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); |
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It looks like you're calling it with a lambda but that would require |
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`DoWithChunkAt` to be a template. The function is really being called with |
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`cFunctionRef<bool(cChunk&)>` which is constructed from the lambda via a |
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templated constructor. This gives you a generic pointer to the lambda which |
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doesn't depend on the type of the function object it references. |
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### Notes |
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- This is similar to a `std::function` but doesn't copy the function object. |
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This means that mutable function objects will be modified for the caller but |
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would not be if using a `std::function` (See #3990 for implications of this). |
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- A `cFunctionRef` has no empty state but is non-owning and so is safe to call as |
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long as the referred object is still alive. */ |
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template <class Ret, class... Args> |
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class cFunctionRef<Ret(Args...)> |
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{ |
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public: |
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/** Construct from a function object. */ |
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template <class FunctionObject> |
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template <class FunctionObject, |
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typename std::enable_if< // Don't disable the default copy constructor
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!std::is_same<typename std::decay<FunctionObject>::type, cFunctionRef>::value, |
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int>::type = 0 |
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> |
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cFunctionRef(FunctionObject && a_FunctionObject) |
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{ |
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// Store an opaque reference to the object.
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