The util::ResultPtr class is a wrapper for util::Result providing syntax sugar to make it less awkward to use with returned pointers. Instead of needing to be deferenced twice with **result or (*result)->member, it only needs to be dereferenced once with *result or result->member. Also when it is used in a boolean context, instead of evaluating to true when there is no error and the pointer is null, it evaluates to false so it is straightforward to determine whether the result points to something.
This PR is only partial a solution to #26004 because while it makes it easier to check for null pointer values, it does not make it impossible to return a null pointer value inside a successful result. It would be possible to enforce that successful results always contain non-null pointers by using a not_null type (https://github.com/bitcoin/bitcoin/issues/24423) in combination with ResultPtr, though.
ryanofsky
commented at 3:57 pm on September 6, 2022:
contributor
In draft state because it’s a partial solution to #26004 and could be discussed more
DrahtBot
commented at 11:11 pm on September 6, 2022:
contributor
The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.
#30342 (kernel, logging: Pass Logger instances to kernel objects by ryanofsky)
If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.
DrahtBot added the label
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on Sep 19, 2022
ryanofsky force-pushed
on Sep 20, 2022
ryanofsky
commented at 6:28 pm on September 20, 2022:
contributor
I also rewrote the commit and PR description. I think this is in a good state to review, despite being based on another PR.
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on Feb 22, 2024
DrahtBot added the label
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on Apr 30, 2024
ryanofsky force-pushed
on May 1, 2024
ryanofsky
commented at 5:56 pm on May 1, 2024:
contributor
Rebased 8ecac0885ef5b6fc2313cd2f8dfb48c10a05db27 -> 9f58eb795ec5592c59f9af3269f004e589a2368f (pr/bresult-ptr.4 -> pr/bresult-ptr.5, compare) on top of latest #25665 (no other changes)
DrahtBot removed the label
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on May 1, 2024
DrahtBot added the label
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on May 20, 2024
refactor: Add util::Result failure values
Add util::Result support for returning more error information. For better error
handling, adds the ability to return a value on failure, not just a value on
success. This is a key missing feature that made the result class not useful
for functions like LoadChainstate() which produce different errors that need to
be handled differently.
This change also makes some more minor improvements:
- Smaller type size. util::Result<int> is 16 bytes, and util::Result<void> is 8
bytes. Previously util::Result<int> and util::Result<void> were 72 bytes.
- More documentation and tests.
41f6b999d0
refactor: Add util::Result::Update() method
Add util::Result Update method to make it possible to change the value of an
existing Result object. This will be useful for functions that can return
multiple error and warning messages, and want to be able to change the result
value while keeping existing messages.
6fff420672
refactor: Use util::Result class in LoadChainstate and VerifyLoadedChainstate79a970d4f1
refactor: Add util::Result multiple error and warning messages
Add util::Result support for returning warning messages and multiple errors,
not just a single error string. This provides a way for functions to report
errors and warnings in a standard way, and simplifies interfaces.
The functionality is unit tested here, and put to use in followup PR
https://github.com/bitcoin/bitcoin/pull/25722
ba959dbed3
test: add static test for util::Result memory usage
Suggested by Martin Leitner-Ankerl <martin.ankerl@gmail.com>
https://github.com/bitcoin/bitcoin/pull/25722#discussion_r1174298529
Co-authored-by: Martin Leitner-Ankerl <martin.ankerl@gmail.com>
The util::ResultPtr class is a wrapper for util::Result providing syntax sugar
to make it less awkward to use with returned pointers. Instead of needing to be
deferenced twice with **result or (*result)->member, it only needs to be
dereferenced once with *result or result->member. Also when it is used in a
boolean context, instead of evaluating to true when there is no error and the
pointer is null, it evaluates to false so it is straightforward to determine
whether the result points to something.
This PR is only partial a solution to #26004 because while it makes it easier
to check for null pointer values, it does not make it impossible to return a
null pointer value inside a successful result. It would be possible to enforce
that successful results always contain non-null pointers by using a not_null
type (https://github.com/bitcoin/bitcoin/issues/24423) in combination with
ResultPtr, though.
40d119fa42
Use ResultPtr<unique_ptr> instead of Result<unique_ptr>73ec37294e
ryanofsky force-pushed
on Jun 17, 2024
DrahtBot removed the label
Needs rebase
on Jun 17, 2024
DrahtBot added the label
Needs rebase
on Jul 2, 2024
DrahtBot
commented at 11:19 am on July 2, 2024:
contributor
🐙 This pull request conflicts with the target branch and needs rebase.
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