Avoid explicitly resetting a std::[experimental::]optional #874
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Now that pybind#851 has removed all multiple uses of a caster, it can just use the default-constructed value with needing a reset. This fixes two issues: 1. With std::experimental::optional (at least under GCC 5.4), the `= {}` would construct an instance of the optional type and then move-assign it, which fails if the value type isn't move-assignable. 2. With older versions of Boost, the `= {}` could fail because it is ambiguous, allowing construction of either `boost::none` or the value type.
|
This is intended as an alternative to #850. |
|
Thanks for simplifying this! Looks good together with the updated casters. The single-use rule is manually enforced right now, but it should become a compiler-enforced feature with #864. |
This was referenced May 27, 2017
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Now that #851 has removed all multiple uses of a caster, it can just use
the default-constructed value with needing a reset. This fixes two
issues:
With std::experimental::optional (at least under GCC 5.4), the
= {}would construct an instance of the optional type and then move-assign
it, which fails if the value type isn't move-assignable.
With older versions of Boost, the
= {}could fail because it isambiguous, allowing construction of either
boost::noneor the valuetype.