Themethod also allows transferable objects in the original value to be transferred rather than cloned to the new object. Transferred objects are detached from the original object and attached to the new object; they are no longer accessible in the original object.
Note: A scenario where this might be useful is when asynchronously validating some data in a buffer before saving it. To avoid the buffer being modified before the data is saved, you can clone the buffer and validate that data. If you also transfer the data, any attempts to modify the original buffer will fail, preventing its accidental misuse.
In this example we create an ArrayBuffer and then clone the object it is a member of, transferring the buffer. We can use the buffer in the cloned object, but if we try to use the original buffer we will get an exception.
\n The method also allows transferable objects in the original value to be transferred rather than cloned to the new object.\n Transferred objects are detached from the original object and attached to the new object; they are no longer accessible in the original object.\n
\n Note: A scenario where this might be useful is when asynchronously validating some data in a buffer before saving it.\n To avoid the buffer being modified before the data is saved, you can clone the buffer and validate that data.\n If you also transfer the data, any attempts to modify the original buffer will fail, preventing its accidental misuse.\n
From 2021-08-13, GitHub is no longer accepting account passwords when authenticating Git operations. You need to add a PAT (Personal Access Token) instead, and you can follow the below method to add a PAT on your system.
For those who don't have this entry: it could be made. one way to do it is- to clone a project. then it will ask for your username and password. instead of password give it the token and then the entry would be made.
GitHub has made changes in password authentication. If you are trying to access Git by username and password then it does not allow you. So use a personal access token instead of a password to access Git everywhere.
It will show all generic credentials. Find your GitHub URL and click on that. Now click on the edit button. And then add the personal access token generated from GitHub into the password field. And click on the Save button.
This message means that you're using a password instead of a personal access token to access GitHub over HTTPS, and that's no longer allowed. GitHub has disabled password authentication because it's common for people to accidentally leak their passwords, and while a personal access token can be restricted to limit the damage, a password cannot.
Then, the next time you try to push or pull, Git will prompt you for a username and password. For the username, enter your GitHub username, and for the password, generate a new personal access token on the appropriate settings page and paste it into the password field. If you're working from the command line, you may not see any indication that the password was successfully pasted; this is normal, so just hit Enter afterwards.
That will save the personal access token in your credential manager for the next time, assuming you have one set up. If you're not sure if you have one set up, run git config credential.helper and see if it outputs anything.
After this step, run the command again for pull/push in the terminal. GitHub will ask to log in with your default browser automatically (make sure you are logged in with GitHub in the default browser).
If the repository is part of an organization, you will also need to sign in to that organization with your personal access token so that the organization will recognize it. If you're already signed in, sign out first.
Reading other solutions on Stack Overflow, I downloaded the GitHub CLI, and added my GitHub account in the Windows command prompt with the access token successfully, and tried to push the repository from Android Studio again, which again failed.
As a security precaution, GitHub automatically removes personal access tokens that haven't been used in a year. To provide additional security, we highly recommend adding expiration to your personal access tokens.
If I am defining an interface with interior mutability, and want to use Cell as part of that, why must the contained type be Copy instead of just Clone? For example, why would it be a bad thing to store a Cell, assuming that's what you actually wanted?
I've done some initial searching about, and have only found vague references to it maybe not being safe, but I don't think I understand why. Which of the differences between Copy and Clone mean that Copy is safe in this case, whereas Clone wouldn't be?
Cell is a tool to extend the normal Rust rule of sharing == no mutation, but being able to be mutated while shared comes with a trade-off: fewer things can be mutated. Some sort of restriction is necessary, or else one could get dangling pointers caused by doing a mutation that invalidates a reference that has previously been retrieved. Cell is designed to never give any references to its interior (the value that can be mutated while shared) to external code, and thus ensures that there's no risk of invalidation. (RefCell is designed to allow "references", aka Ref and RefMut, but it needs those fancy references so that it can track them.)
The problem with Clone is that it requires &self, that is, Cell would need to pass a reference to its interior into the external/arbitrary/user-defined code of a Clone implementation. Once this reference exists, the Clone implementation could theoretically use another path to the Cell (this is where the sharing comes in) to invalidate it. On the other hand, T: Copy is safe because it means T can be duplicated in a known, controlled way (a byte copy) without having to run any user-defined code, and thus no references to the interior can escape.
A reference like &i32 shouldn't change---while it lives the i32 is immutable---meaning printing it multiple times should always be the same (no matter what happens between them), but this code prints:
This is undefined behaviour, and could easily lead to memory corruption e.g. if data included some pointers, they'll get set to an effectively random value (Option is nice enough to zero in this case, but there's no guarantee about what value will be there), meaning code could segfault---if you're lucky---or end up writing to random parts of memory.
Ah, I understand. Thanks. Coming from a C++ background, I hadn't taken into account that Copy can't be overridden like that. That's a subtle distinction I hadn't expected to be attached to the primary semantic difference (copy vs move) of the two traits.
Would it help matters to have a 'static restriction as well as Clone? If I'm reading it correctly, I would expect the first example from eefriedman to panic instead of corrupting data. (Which seems like a reasonable thing to be risking if you're performing an interior mutation during a clone, really...)
Sorry, I wasn't clear. The use case in my project is a re-implementation of Cell restricted to Clone instead of Copy, rather than a wrapper around RefCell. At that point, it has the semantics implied by your example implementation above, but doesn't have the extra memory and performance overhead that come along with RefCell. If you're storing Copy data in it, then it has the same overhead as Cell, and it doesn't panic unless the Clone implementation does.
The semantic difference is really mainly a consequence of the Copy trait's guarantees: both a copy and a move are identical (always byte copies), so a type implementing Copy says that the source of such a "move/copy" is safe to continue using. That is, that Copy is a valid way to duplicate the value.
If I'm reading it correctly, I would expect the first example from eefriedman to panic instead of corrupting data. (Which seems like a reasonable thing to be risking if you're performing an interior mutation during a clone, really...)
I think (but don't know, since there's no description from them) @eefriedman's example was using the panic as a proxy for "bad stuff would happen", if the RefCell was replaced with UnsafeCell (as in the real Cell or my reimplementation)---which doesn't have the dynamic checks of RefCell---the problem wouldn't have been caught in such an obvious way, leading to undefined behaviour/memory corruption as in my versions.
Thanks for explaining that to me all the way. As an experiment, I changed my CloneCell to store UnsafeCell and made it expect a value before performing the clone() (enforced via set() accepting a &T instead of just T) which introduces that barrier, and got it to panic instead of segfaulting. I'm not sure if that's any more efficient than just using RefCell. It might be in some cases due to some of the optimizations that Option gets to take advantage of on some types, but I doubt it.
My product is need to clone the LVDS and HDMI, the LVDS is primary.
I have already configure these display successful, but it is extended mode.
I enable by device tree overlay (that i have a little bit modified) in /boot/overlays.txt
Based on our requirement, we plan to use JIRA service desk for our customers use. But we a requirement whenever customer creates a ticket in service desk, we should be able to create a clone of a ticket to our JIRA software project.
Cloning between (cloud) instances is currently not possible. If you're interested in that feature for Jira cloud, please get in touch with our support team. Your feedback would be very helpful for us to prioritize our work.
Fast Clone is the Veeam Backup & Replication technology that helps create quick file copies. Fast Clone increases the speed of synthetic backup creation and transformation, reduces disk space requirements and decreases the load on storage devices.
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