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Stop cFunctionRef constructor from disabling default copy constructor. (#4173)

* Stop cFunctionRef constructor from disabling default copy constructor.
+ cFunctionRef: Improve documentation
master
peterbell10 4 years ago
committed by Tiger Wang
parent
commit
b5f29d5d2c
  1. 2
      Doxyfile
  2. 37
      src/FunctionRef.h

2
Doxyfile

@ -194,7 +194,7 @@ SEPARATE_MEMBER_PAGES = NO
# The TAB_SIZE tag can be used to set the number of spaces in a tab.
# Doxygen uses this value to replace tabs by spaces in code fragments.
TAB_SIZE = 2
TAB_SIZE = 4
# This tag can be used to specify a number of aliases that acts
# as commands in the documentation. An alias has the form "name=value".

37
src/FunctionRef.h

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

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