The status type used to represent the status of this Result. Defaults to pw::Status.

Generic value_type member for use within generic programming. This usage is analogous to that of std::optional::value_type.

Constructs a new Result<T> with a pw::Status::Unknown() status.

This constructor is marked explicit to prevent usages in return values (e.g. return {}) under the misconception that Result<std::vector<int>> (for example) will be initialized with an empty vector.

Only enabled when StatusType is pw::Status.

Result<T, StatusType> is copy constructible if T is copy constructible.

Result<T, StatusType> is move constructible if T is move constructible.

Constructs a new Result<T, StatusType> from a Result<U, StatusType> when T is constructible from U.

To avoid ambiguity, these constructors are disabled if T is also constructible from Result<U, StatusType>. This constructor is explicit if and only if the corresponding construction of T from U is explicit. (This constructor inherits its explicitness from the underlying constructor.)

Constructs a new Result<T, StatusType> with a non-OK status.

After calling this constructor, this->ok() will be false and calls to value() will trigger a PW_ASSERT.

The constructor takes any type U that is constructible/convertible to status_type. This constructor is explicit if and only if U is not implicitly convertible to status_type.

Disabled when T is StatusType (in which case constructing from a status initializes the contained value; use reset() to set an error status).

Precondition

!status_type(std::forward<U>(v)).ok(). This requirement is asserted via PW_ASSERT.

Constructs the inner value T in-place using the provided args, using the T(args...) constructor.

Constructs the inner value T in-place using the provided arg, using the T(U) (direct-initialization) constructor.

Precondition

This constructor is only valid if T can be constructed from a U. Can accept move or copy constructors.

This constructor is explicit if U is not convertible to T. To avoid ambiguity, this constructor is disabled if U is a Result<J, StatusType>, where J is convertible to T.

Returns

The Result from invoking func() on the held value if ok(). Otherwise, returns a Result with the contained error status.

Returns

The Result from invoking func() on the held value if ok(). Otherwise, returns a Result with the contained error status.

Returns

The Result from invoking func() on the held value if ok(). Otherwise, returns a Result with the contained error status.

Returns

The Result from invoking func() on the held value if ok(). Otherwise, returns a Result with the contained error status.

Reconstructs the inner value T in-place using the provided args, using the T(args...) constructor.

Returns

A reference to the reconstructed T.

Reconstructs the inner value T in-place using the provided args, using the T(args...) constructor.

Returns

A reference to the reconstructed T.

Ignores any errors. This method does nothing except potentially suppress complaints from any tools that are checking that errors are not dropped.

Returns

Whether or not this Result<T, StatusType> holds a T value. This member function is analogous to Status::ok() and should be used similarly to check the status of return values.

Example:

Returns

A reference to the current value. Only checks if a value is present if PW_ASSERT_ENABLE_DEBUG is enabled (via PW_DASSERT).

Precondition

this->ok() == true, otherwise the behavior is undefined.

Use this->ok() to verify that there is a current value within the Result<T, StatusType>. Alternatively, see the value() member function for a similar API that guarantees crashing if there is no current value.

Returns

A reference to the current value. Only checks if a value is present if PW_ASSERT_ENABLE_DEBUG is enabled (via PW_DASSERT).

Precondition

this->ok() == true, otherwise the behavior is undefined.

Use this->ok() to verify that there is a current value within the Result<T, StatusType>. Alternatively, see the value() member function for a similar API that guarantees crashing if there is no current value.

Returns

A reference to the current value. Only checks if a value is present if PW_ASSERT_ENABLE_DEBUG is enabled (via PW_DASSERT).

Precondition

this->ok() == true, otherwise the behavior is undefined.

Use this->ok() to verify that there is a current value within the Result<T, StatusType>. Alternatively, see the value() member function for a similar API that guarantees crashing if there is no current value.

Returns

A reference to the current value. Only checks if a value is present if PW_ASSERT_ENABLE_DEBUG is enabled (via PW_DASSERT).

Precondition

this->ok() == true, otherwise the behavior is undefined.

Use this->ok() to verify that there is a current value within the Result<T, StatusType>. Alternatively, see the value() member function for a similar API that guarantees crashing if there is no current value.

Returns

A pointer to the current value. Only checks if a value is present if PW_ASSERT_ENABLE_DEBUG is enabled (via PW_DASSERT).

Precondition

this->ok() == true, otherwise the behavior is undefined.

Use this->ok() to verify that there is a current value.

Returns

A pointer to the current value. Only checks if a value is present if PW_ASSERT_ENABLE_DEBUG is enabled (via PW_DASSERT).

Precondition

this->ok() == true, otherwise the behavior is undefined.

Use this->ok() to verify that there is a current value.

Result<T, StatusType> is copy assignable if T is copy constructible and copy assignable.

Assigns a Result<T, StatusType> from a Result<U, StatusType>.

Precondition

These overloads only apply if Result<T, StatusType> is constructible and assignable from Result<U, StatusType> and Result<T, StatusType> cannot be directly assigned from Result<U, StatusType>.

If both Result<T, StatusType> and Result<U, StatusType> are OK, assigns U to T directly.

If Result<T, StatusType> is OK and Result<U, StatusType> contains an error code, destroys the value of Result<T, StatusType> and assigns the error status from Result<U, StatusType>.

If Result<T, StatusType> contains an error code and Result<U, StatusType> is OK, directly initializes T from U.

If both Result<T, StatusType> and Result<U, StatusType> contain an error code, assigns the status in Result<U, StatusType> to Result<T, StatusType>.

Result<T, StatusType> is move assignable if T is move constructible and move assignable.

Assigns a non-OK status to this Result<T, StatusType>, destroying any currently held value.

Disabled when T is StatusType (in which case assigning a status updates the contained value; use reset() to set an error status).

Precondition

!status_type(std::forward<U>(v)).ok(). This requirement is asserted via PW_ASSERT.

Perfect-forwarding value assignment operator.

If *this contains a T value before the call, the contained value is assigned from std::forward<U>(v). Otherwise, it is directly initialized from std::forward<U>(v).

Precondition

std::is_constructible_v<T, U> is true.

std::is_assignable_v<T&, U> is true.

std::is_same_v<Result<T, StatusType>, std::remove_cvref_t<U>> is false.

Assigning U to T is not ambiguous. If U is Result<V, StatusType> and T is constructible and assignable from both Result<V, StatusType> and V, the assignment is considered bug-prone and ambiguous and thus will fail to compile. For example:

Result<bool> s1 = true; // s1.ok() && *s1 == true

Result<bool> s2 = false; // s2.ok() && *s2 == false

s1 = s2; // ambiguous, `s1 = *s2` or `s1 = bool(s2)`?

Returns

This Result<T, StatusType> if it has a value, otherwise invokes the given function with status(). The function must return a type convertible to Result<T, StatusType> or void.

Returns

This Result<T, StatusType> if it has a value, otherwise invokes the given function with status(). The function must return a type convertible to Result<T, StatusType> or void.

Returns

This Result<T, StatusType> if it has a value, otherwise invokes the given function with status(). The function must return a type convertible to Result<T, StatusType> or void.

Returns

This Result<T, StatusType> if it has a value, otherwise invokes the given function with status(). The function must return a type convertible to Result<T, StatusType> or void.

Destroys the contained value, if any, and sets the status. The status must not be OK. To avoid a runtime check, use the reset<kCode>() function template whenever possible.

Destroys the contained value, if any, and sets the status. The status must not be OK. To avoid a runtime check, use the reset<kCode>() function template whenever possible.

Destroys the contained value, if any, and sets the status. The status must not be OK. To avoid a runtime check, use the reset<kCode>() function template whenever possible.

Returns

The current status_type contained within the Result<T, StatusType>. If Result<T, StatusType> contains a T, then this function returns an OK status (ok() == true).

Returns

A Result<U, StatusType> containing the result of invoking function on the held value if *this contains a value. Otherwise, returns a Result<U, StatusType> with the same status as *this.

Returns

A Result<U, StatusType> containing the result of invoking function on the held value if *this contains a value. Otherwise, returns a Result<U, StatusType> with the same status as *this.

Returns

A Result<U, StatusType> containing the result of invoking function on the held value if *this contains a value. Otherwise, returns a Result<U, StatusType> with the same status as *this.

Returns

A Result<U, StatusType> containing the result of invoking function on the held value if *this contains a value. Otherwise, returns a Result<U, StatusType> with the same status as *this.

Returns

A reference to the held value if this->ok(). Otherwise, terminates the process via PW_ASSERT.

If you have already checked the status using this->ok(), you probably want to use operator*() or operator->() to access the value instead of value.

For value types that are cheap to copy, prefer simple code:

Otherwise, if the value type is expensive to copy, but can be left in the Result<T, StatusType>, simply assign to a reference:

Otherwise, if the value type supports an efficient move, it can be used as follows:

The std::move on result instead of on the whole expression enables warnings about possible uses of the result object after the move.

Returns

A reference to the held value if this->ok(). Otherwise, terminates the process via PW_ASSERT.

If you have already checked the status using this->ok(), you probably want to use operator*() or operator->() to access the value instead of value.

For value types that are cheap to copy, prefer simple code:

Otherwise, if the value type is expensive to copy, but can be left in the Result<T, StatusType>, simply assign to a reference:

Otherwise, if the value type supports an efficient move, it can be used as follows:

The std::move on result instead of on the whole expression enables warnings about possible uses of the result object after the move.

Returns

A reference to the held value if this->ok(). Otherwise, terminates the process via PW_ASSERT.

If you have already checked the status using this->ok(), you probably want to use operator*() or operator->() to access the value instead of value.

For value types that are cheap to copy, prefer simple code:

Otherwise, if the value type is expensive to copy, but can be left in the Result<T, StatusType>, simply assign to a reference:

Otherwise, if the value type supports an efficient move, it can be used as follows:

The std::move on result instead of on the whole expression enables warnings about possible uses of the result object after the move.

Returns

A reference to the held value if this->ok(). Otherwise, terminates the process via PW_ASSERT.

If you have already checked the status using this->ok(), you probably want to use operator*() or operator->() to access the value instead of value.

For value types that are cheap to copy, prefer simple code:

Otherwise, if the value type is expensive to copy, but can be left in the Result<T, StatusType>, simply assign to a reference:

Otherwise, if the value type supports an efficient move, it can be used as follows:

The std::move on result instead of on the whole expression enables warnings about possible uses of the result object after the move.

Returns

The current value if this->ok() == true. Otherwise constructs a value using the provided default_value.

Unlike value, this function returns by value, copying the current value if necessary. If the value type supports an efficient move, it can be used as follows:

Unlike with value, calling std::move() on the result of value_or will still trigger a copy.

Returns

The current value if this->ok() == true. Otherwise constructs a value using the provided default_value.

Unlike value, this function returns by value, copying the current value if necessary. If the value type supports an efficient move, it can be used as follows:

Unlike with value, calling std::move() on the result of value_or will still trigger a copy.

Checks the equality of two Result<T, StatusType> objects. Only enabled if T is equality comparable.

Checks the equality of two Result<T, StatusType> objects. Only enabled if T is equality comparable.

Checks the equality of two Result<T, StatusType> objects. Only enabled if T is equality comparable.

Checks the equality of two Result<T, StatusType> objects. Only enabled if T is equality comparable.

Checks the equality of two Result<T, StatusType> objects. Only enabled if T is equality comparable.

Checks the equality of two Result<T, StatusType> objects. Only enabled if T is equality comparable.

Checks the equality of two Result<T, StatusType> objects. Only enabled if T is equality comparable.

Checks the equality of two Result<T, StatusType> objects. Only enabled if T is equality comparable.

Checks equality of a Result<T, StatusType> and a value. A Result without a value never compares equal to a value. This overload is only enabled if T is equality comparable with U, and U is not a Result, status, or status code (unless T itself is StatusType or StatusType::Code).

Compares the status of a Result<T, StatusType> with a status. A Result holding a value compares equal to an OK status.

Disabled when T is StatusType (in which case operator== compares against the held StatusType value).

Compares the status of a Result<T, StatusType> with a status code.

Disabled when T is StatusType or StatusType::Code (in which case operator== compares against the held value).

Checks the equality of two Result<T, StatusType> objects. Only enabled if T is equality comparable.

Checks the equality of two Result<T, StatusType> objects. Only enabled if T is equality comparable.

Checks the equality of two Result<T, StatusType> objects. Only enabled if T is equality comparable.