- set() was silently deprecated in favour of reset() FEB-2018
since the original additional check for overwriting an existing
pointer was never used. The reset(...) name is more consistent
with unique_ptr, tmp etc.
Now emit deprecations for set().
- use direct test for autoPtr, tmp instead of valid() method.
More consistent with unique_ptr etc.
STYLE: eliminate redundant ptr() use on cloned quantities
- releases ownership of the pointer. A no-op (and returns nullptr)
for references.
Naming consistent with unique_ptr and autoPtr.
DOC: adjust wording for memory-related classes
- add is_const() method for tmp, refPtr.
Drop (ununsed and confusing looking) isTmp method from refPtr
in favour of is_pointer() or movable() checks
ENH: noexcept for some pTraits methods, remove redundant 'inline'
- test for const first for tmp/refPtr (simpler logic)
- deprecated Feb-2018, but not marked as such.
The set() method originally enforce an additional run-time check
(Fatal if pointer was already set), but this was rarely used.
In fact, the set() method was invariably used in constructors
where the pointer by definition was unset.
Can now mark as deprecated to catch the last of these.
We prefer reset() for similarity with std::unique_ptr
Eg,
FOAM_EXTRA_CXXFLAGS="-DFoam_autoPtr_deprecate_setMethod" wmake
- was marked as transitional/deprecated (2018-02), now deleted.
- avoids unexpected stealing of the pointer.
Use the move assignment it that is the intention.
- improves similarity to autoPtr. Simplifies coding.
Example,
tmp<volScalarField> tfield;
// sometime later...
tfield.reset
(
volScalarField::New("myfield", mesh, dimensionedScalar(Zero))
);
- as per tmp, disallow tmpNrc assignment from literal nullptr
- as per autoPtr, allow explicit test as bool (same as valid).
- Can result in inadvertent conversions where the user should really
know or check if the pointer is valid prior to using.
- Still have several places to fix that are using the deprecated copy
construct and copy assignment
- Start brief descriptions with 'Deprecated(YYYY-MM)' so that it is
readily visible in the short method description. Consistent date
format (YYYY-MM), placed immediately after the \deprecated tag.
- behaves the same as the valid() method, but can be queried directly
like a normal raw pointer and as per std::unique_ptr.
Eg,
autoPtr<T> ptr = ...
if (ptr) ...
Improve alignment of its behaviour with std::unique_ptr
- element_type typedef
- release() method - identical to ptr() method
- get() method to get the pointer without checking and without releasing it.
- operator*() for dereferencing
Method name changes
- renamed rawPtr() to get()
- renamed rawRef() to ref(), removed unused const version.
Removed methods/operators
- assignment from a raw pointer was deleted (was rarely used).
Can be convenient, but uncontrolled and potentially unsafe.
Do allow assignment from a literal nullptr though, since this
can never leak (and also corresponds to the unique_ptr API).
Additional methods
- clone() method: forwards to the clone() method of the underlying
data object with argument forwarding.
- reset(autoPtr&&) as an alternative to operator=(autoPtr&&)
STYLE: avoid implicit conversion from autoPtr to object type in many places
- existing implementation has the following:
operator const T&() const { return operator*(); }
which means that the following code works:
autoPtr<mapPolyMesh> map = ...;
updateMesh(*map); // OK: explicit dereferencing
updateMesh(map()); // OK: explicit dereferencing
updateMesh(map); // OK: implicit dereferencing
for clarity it may preferable to avoid the implicit dereferencing
- prefer operator* to operator() when deferenced a return value
so it is clearer that a pointer is involve and not a function call
etc Eg, return *meshPtr_; vs. return meshPtr_();
All of the access methods for autoPtr include validity checks and will
fail if the underlying point is NULL. In some cases, however, we'd
like to retain the automatic deletion mechanism, but still address a
nullptr. This is mostly for cases in which a file-stream should be
allocated, but only on the master process. For these cases we'd still
like to pass through and reference the underlying pointer (eg, to
obtain the correct method call) without tripping the pointer check
mechanism. If we attempt to use the ptr() method, the autoPtr memory
management is bypassed and we risk memory leaks.
Instead provide an alternative mechanism to obtain the raw underlying
pointers/references. Use rawPtr() and rawRef() for these potentially
useful, but also potentially dangerous, operations.
- Normally use '()' to deference. This has extra safety and issues a
fatal error if the underlying pointer is not valid.
However, in some cases we are happy with getting a null reference.
The refOrNull() method returns the reference without any checking.
Usage example:
autoPtr<OFstream> osPtr;
if (Pstream::master())
{
osPtr.reset(new OFstream(...));
}
writeViaMaster(osPtr.refOrNull());
- The writeViaMaster() call takes an OFstream reference,
but this is only used directly on the master.
The slaves will pass things through to the master.
To be used instead of zeroGradientFvPatchField for temporary fields for
which zero-gradient extrapolation is use to evaluate the boundary field
but avoiding fields derived from temporary field using field algebra
inheriting the zeroGradient boundary condition by the reuse of the
temporary field storage.
zeroGradientFvPatchField should not be used as the default patch field
for any temporary fields and should be avoided for non-temporary fields
except where it is clearly appropriate;
extrapolatedCalculatedFvPatchField and calculatedFvPatchField are
generally more suitable defaults depending on the manner in which the
boundary values are specified or evaluated.
The entire OpenFOAM-dev code-base has been updated following the above
recommendations.
Henry G. Weller
CFD Direct
