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docs: make some text changes on Section Macros

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(1) In contrast to `that`, `so that` expresses `result` indicated by the sentence, not `reason`;
(2) `block` is an expression, and may be have an expression, so I add `optional an expression` to make more precise;
(3) When I read here, I was confused with what `the child` referred to. After modification, it would be better.
This commit is contained in:
Tang Chenglong
2016-03-26 23:59:16 +08:00
parent 346d0d5175
commit bbba872dde
1 changed files with 4 additions and 4 deletions
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8
src/doc/book/macros.md
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@@ -337,8 +337,8 @@ fn main() {
} }
``` ```
Instead you need to pass the variable name into the invocation, so it’s tagged Instead you need to pass the variable name into the invocation, so that it’s
with the right syntax context. tagged with the right syntax context.
```rust ```rust
macro_rules! foo { macro_rules! foo {
@@ -470,7 +470,7 @@ which syntactic form it matches.
* `ty`: a type. Examples: `i32`; `Vec<(char, String)>`; `&T`. * `ty`: a type. Examples: `i32`; `Vec<(char, String)>`; `&T`.
* `pat`: a pattern. Examples: `Some(t)`; `(17, 'a')`; `_`. * `pat`: a pattern. Examples: `Some(t)`; `(17, 'a')`; `_`.
* `stmt`: a single statement. Example: `let x = 3`. * `stmt`: a single statement. Example: `let x = 3`.
* `block`: a brace-delimited sequence of statements. Example: * `block`: a brace-delimited sequence of statements and optional an expression. Example:
`{ log(error, "hi"); return 12; }`. `{ log(error, "hi"); return 12; }`.
* `item`: an [item][item]. Examples: `fn foo() { }`; `struct Bar;`. * `item`: an [item][item]. Examples: `fn foo() { }`; `struct Bar;`.
* `meta`: a "meta item", as found in attributes. Example: `cfg(target_os = "windows")`. * `meta`: a "meta item", as found in attributes. Example: `cfg(target_os = "windows")`.
@@ -509,7 +509,7 @@ A macro defined within the body of a single `fn`, or anywhere else not at
module scope, is visible only within that item. module scope, is visible only within that item.
If a module has the `macro_use` attribute, its macros are also visible in its If a module has the `macro_use` attribute, its macros are also visible in its
parent module after the child’s `mod` item. If the parent also has `macro_use` parent module after its `mod` item. If the parent also has `macro_use`
then the macros will be visible in the grandparent after the parent’s `mod` then the macros will be visible in the grandparent after the parent’s `mod`
item, and so forth. item, and so forth.