I am not mentioning #[unsafe_drop_flag] because it should go away
eventually, and also because it's just an attribute, it's not
really a use of the `unsafe` keyword.
Fixes#26345
In Chapter 5.9 (References and Borrowing), there is an example [at the very end](https://doc.rust-lang.org/stable/book/references-and-borrowing.html#use-after-free) which shows that declaring a reference before declaring the variable that it points to results in a compilation error. The book does not really mention why this happens though -- in the sections before, it has described how different scopes affects the lifetime of resources, but there is no mention of how resources within the same scope work.
This confused me a little, so I asked on #rust and got the answer that the resources are destroyed in the reverse order that they are declared, but the book makes no mention of it (as far as I can find) -- except in Chapter 5.21 (Drop), where it says:
> When `x` goes out of scope at the end of `main()`, the code for `Drop` will run. `Drop` has one method, which is also called `drop()`. It takes a mutable reference to `self`.
>
> That’s it! The mechanics of `Drop` are very simple, but there are some subtleties. For example, values are dropped in the opposite order they are declared. [...]
---
I feel like Chapter 5.9 (References and Borrowing) is probably the best place to put this information (as I have done in my additions), since it deals with other types of referencing and borrowing. However, since English is not my native language, the wording of my additions perhaps are a little "off" -- any feedback on them is appreciated.
In particular, I found that the disclaimer (promised in the second paragraph) doesn't stand out right now. I think the extra headers help with scanning this document, and making it easier to discern which steps are relevant to my particular flow through the options.
In particular, I found that the disclaimer (promised in the second paragraph) doesn't stand out right now. I think the extra headers help with scanning this document, and making it easier to discern which steps are relevant to my particular flow through the options.
I'm currently reading the rust book and this variable name tripped me up.
Because it was called "input", I thought at first it might contain the line
read by read_line(). This new variable name will be more instructive to rust
beginners.
Since the "Book" already avoids jQuery in its inline script tags and playpen.js is tiny, I figured I would convert it to plain old JS as well.
Side note: This is a separate issue, but another thing I noticed in my testing is that the "⇱" character doesn't display correctly in Chrome on Windows 7. (Firefox and IE work fine; other browsers not tested)
r? @steveklabnik
Edit: Github didn't like the "script" tag above
Edit 2: Actually, now IE seems to render "⇱" fine for me. Odd.
I'm surprised that bitwise operators `&`, `|` and `^` are implemented for `bool` arguments, because inspection of boolean's bits is not something that should be encouraged and because `&&` -> `&` is a common typo, but if they are implemented, then their behavior should be documented.
The "unit value" is a value of the "unit type," not the "unit value type." Regardless of correctness, this straight syntax is easier to grok.
Part of #16676
Sorry if something's off here, it's my first pull request to rust!
Use result of the computation to prevent the compiler from optimising
too much. Change `_x` to `x` and therefore remove the paragraph about
the underscore.
Fixes#25855.
r? @steveklabnik
Use result of the computation to prevent the compiler from optimising
too much. Change `_x` to `x` and therefore remove the paragraph about
the underscore.
Fixes#25855.
Explain the --bin flag in terms of the difference
between shipping binary and library code
I'm not sure if my explanation is even quite correct, but as a newbie coming from Ruby, this is my best guess. (In Rubyland, libraries always ship with the source code because there's no other form you can ship. :) )
In the discussion of returning closures, it seems like the example code got simplified, but only the later copies got fixed. The final working code has `factory` returning `|x| x + num`, but the earlier code has `|x| vec.push(x)`.
The first form seemed to have more distracting characteristics, and the code wasn't right anyway, so I changed them to all use the second form, and updated the error messages.
r? @steveklabnik
Doc patch for #26120. Extra words here, because "value" is repeated.
I haven't read about whether/how it should go to stable (sorry), but I think it would help newcomers.
Thanks,
The text claimed 'any borrow must last for a _smaller_ scope than the
owner', however the accurate way of describing the comparison is
inclusive (i.e., 'less than or equal to' vs. 'less than').
The text claimed 'any borrow must last for a _smaller_ scope than the
owner', however the accurate way of describing the comparison is
inclusive (i.e., 'less than or equal to' vs. 'less than').
For a user following the path of reading Chapter 5: Syntax & Symantics
prior to Chapter 4: Learn Rust, this will be the first time they have
encountered executable tests inside documentation comments.
The test will fail because the `add_one` function is not defined in
the context of the doctest. This might not be the optimal place to
introduce and explain the `/// #` notation but I think it is important
that this snippet pass as a test when `rustdoc --test` is run against
it.
The doc indicates that you can replace 'before' with 'after' showing the use of try!. The two examples should be equivalent, but they are not.
In the File::create we were inducing a panic before in case of error, not propagating. It is important for newbies (like myself) to understand that try! propagates failures, while unwrap can induce a panic.
The other alternative is to make the 'before' File::create also manually handle Err like the other calls. Either way it would be consistent.
As mentioned in #25893 the copy trait is not very well explained for beginners. There is no clear mention that all primitive types implement the copy trait and there are not a lot of examples.
With this change I try to make it more visible and understandable for new users.
I myself have struggled with this, see [my question on stackoverflow](http://stackoverflow.com/questions/30540419/why-are-booleans-copyable-even-though-the-documentation-doesnt-indicate-that). And I want to make it more transparent for others.
I filed issue #25893 but I thought that I could give it a shot myself to relieve some of the work from the devs :)
If it is not well written or there are some changes to be made before it can be merged, let me know.
Cheers,
Mathieu
For a user following the path of reading Chapter 5: Syntax & Symantics
prior to Chapter 4: Learn Rust, this will be the first time they have
encountered executable tests inside documentation comments.
The test will fail because the `add_one` function is not defined in
the context of the doctest. This might not be the optimal place to
introduce and explain the `/// #` notation but I think it is important
that this snippet pass as a test when `rustdoc --test` is run against
it if it is going to be shown.
The sensible default used here for the version number in the
auto-generated Cargo.toml is 0.1.0, not 0.0.1 (at least as of cargo
0.2.0-nightly efb482d).
The statement is not completely exact, because it is valid to have
both 0 non-mutable references and 1 mutable reference. Instead, use
the same wording as in mutability.md.
Hi
I added a little section in the for loops about the `enumerate()` function.
I think it's useful for beginners to know this function and how you can use it.
I used the title loopcounter, but it's probably not the best word to describe it. So let me know if there is a better word :)
The statement is not completely exact, because it is valid to have
both 0 non-mutable references and 1 mutable reference. Instead, use
the same wording as in mutability.md.
My main sources of information are [RFC401](https://github.com/rust-lang/rfcs/blob/master/text/0401-coercions.md), the rust IRC channel, and a bunch of experiments to figure out what `rustc` currently supports.
Note that the RFC calls for some coercion behaviour that is not implemented yet (see #18469).
The documentation in this PR mostly covers current behaviour of rust and doesn't document the future behaviour. I haven't written about receiver expression coercion.
I would be happy to rewrite/adapt the PR according to feedback.
r? @steveklabnik
This was always a weird feature, and isn't being used in the compiler.
Static assertions should be done better than this.
This implements RFC #1096.
Fixes#13951Fixes#23008Fixes#6676
This is behind a feature gate, but that's still a
[breaking-change]
The doc indicates that you can replace 'before' with 'after' showing the use of try!. The two examples should be equivalent, but they are not.
In the File::create we were inducing a panic before in case of error, not propagating. It is important for newbies (like myself) to understand that try! propagates failures, while unwrap can induce a panic.
The other alternative is to make the 'before' File::create also manually handle Err like the other calls. Either way it would be consistent.
As mentioned in #25893 the copy trait is not very well explained for beginners. There is no clear mention that all primitive types implement the copy trait and there are not a lot of examples.
With this change I try to make it more visible and understandable for new users.
I myself have struggled with this, see [my question on stackoverflow](http://stackoverflow.com/questions/30540419/why-are-booleans-copyable-even-though-the-documentation-doesnt-indicate-that). And I want to make it more transparent for others.
I filed issue #25893 but I thought that I could give it a shot myself to relieve some of the work from the devs :)
If it is not well written or there are some changes to be made before it can be merged, let me know.
Cheers,
Mathieu
