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doc: mention module shadowing (#7051)

pull/7070/head
Lukas Neubert 2020-12-01 16:09:33 +01:00 committed by GitHub
parent 5b6eb7b2c9
commit 4f540e6ac3
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2 changed files with 22 additions and 10 deletions
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28
doc/docs.md
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@ -97,7 +97,7 @@ Anything you can do in other languages, you can do in V.
</table> </table>
<!-- <!--
There are several special keywords, which you can put after the code fences for v. There are several special keywords, which you can put after the code fences for v.
These are: These are:
compile - default, you do not need to specify it. cmd/tools/check-md.v compile the example. compile - default, you do not need to specify it. cmd/tools/check-md.v compile the example.
ignore - ignore the example, useful for examples that just use the syntax highlighting ignore - ignore the example, useful for examples that just use the syntax highlighting
@ -297,11 +297,12 @@ In development mode the compiler will warn you that you haven't used the variabl
In production mode (enabled by passing the `-prod` flag to v – `v -prod foo.v`) In production mode (enabled by passing the `-prod` flag to v – `v -prod foo.v`)
it will not compile at all (like in Go). it will not compile at all (like in Go).
<!-- this should be `failcompile`, but it compiles -->
```v ```v
fn main() { fn main() {
a := 10 a := 10
if true { if true {
a := 20 // error: shadowed variable a := 20 // error: redefinition of `a`
} }
// warning: unused variable `a` // warning: unused variable `a`
} }
@ -310,6 +311,17 @@ fn main() {
Unlike most languages, variable shadowing is not allowed. Declaring a variable with a name Unlike most languages, variable shadowing is not allowed. Declaring a variable with a name
that is already used in a parent scope will cause a compilation error. that is already used in a parent scope will cause a compilation error.
You can shadow imported modules though, as it is very useful in some situations:
```v ignore
import ui
import gg
fn draw(ctx &gg.Context) {
gg := ctx.parent.get_ui().gg
gg.draw_rect(...)
}
```
## Types ## Types
### Primitive types ### Primitive types
@ -1012,7 +1024,7 @@ Here `i` doesn't need to be declared with `mut` since it's always going to be mu
#### Labelled break & continue #### Labelled break & continue
`break` and `continue` control the innermost `for` loop by default. `break` and `continue` control the innermost `for` loop by default.
You can also use `break` and `continue` followed by a label name to refer to an outer `for` You can also use `break` and `continue` followed by a label name to refer to an outer `for`
loop: loop:
```v ```v
@ -1249,7 +1261,7 @@ struct ButtonConfig {
height int = 20 height int = 20
} }
struct Button { struct Button {
text string text string
width int width int
height int height int
@ -1738,7 +1750,7 @@ sum := World(Moon{})
assert sum.type_name() == 'Moon' assert sum.type_name() == 'Moon'
println(sum) println(sum)
``` ```
The built-in method `type_name` returns the name of the currently held The built-in method `type_name` returns the name of the currently held
type. type.
#### Dynamic casts #### Dynamic casts
@ -1781,7 +1793,7 @@ if w is Mars {
} }
} }
``` ```
`w` has type `Mars` inside the body of the `if` statement. This is `w` has type `Mars` inside the body of the `if` statement. This is
known as *flow-sensitive typing*. You can also specify a variable name: known as *flow-sensitive typing*. You can also specify a variable name:
```v ignore ```v ignore
@ -2025,7 +2037,7 @@ At the moment only one type parameter named `T` is supported.
Currently generic function definitions must declare their type parameters, but in Currently generic function definitions must declare their type parameters, but in
future V will infer generic type parameters from single-letter type names in future V will infer generic type parameters from single-letter type names in
runtime parameter types. This is why `find_by_id` can omit `<T>`, because the runtime parameter types. This is why `find_by_id` can omit `<T>`, because the
receiver argument `r` uses a generic type `T`. receiver argument `r` uses a generic type `T`.
Another example: Another example:
@ -2187,7 +2199,7 @@ fn main () {
// do something if no channel has become ready within 0.5s // do something if no channel has become ready within 0.5s
} }
} }
} }
``` ```
The timeout branch is optional. If it is absent `select` waits for an unlimited amount of time. The timeout branch is optional. If it is absent `select` waits for an unlimited amount of time.

4
tutorials/building-a-simple-web-blog-with-vweb.md
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@ -24,14 +24,14 @@ The code is available <a href='https://github.com/vlang/v/tree/master/tutorials/
``` ```
wget https://github.com/vlang/v/releases/latest/download/linux.zip wget https://github.com/vlang/v/releases/latest/download/linux.zip
unzip linux.zip unzip v_linux.zip
cd v cd v
sudo ./v symlink sudo ./v symlink
``` ```
Now V should be globally available on your system. Now V should be globally available on your system.
> On macOS use `macos.zip`, on Windows - `windows.zip`. > On macOS use `v_macos.zip`, on Windows - `v_windows.zip`.
If you use a BSD system, Solaris, Android, or simply want to install V If you use a BSD system, Solaris, Android, or simply want to install V
from source, follow the simple instructions here: from source, follow the simple instructions here:
https://github.com/vlang/v#installing-v-from-source https://github.com/vlang/v#installing-v-from-source