mirror of
https://github.com/erg-lang/erg.git
synced 2025-09-30 04:44:44 +00:00
111 lines
2.4 KiB
Markdown
111 lines
2.4 KiB
Markdown
# 提示
|
|
|
|
[](https://gezf7g7pd5.execute-api.ap-northeast-1.amazonaws.com/default/source_up_to_date?owner=erg-lang&repos=erg&ref=main&path=doc/EN/tips.md&commit_hash=8673a0ce564fd282d0ca586642fa7f002e8a3c50)
|
|
|
|
## 想要更改顯示錯誤的語言
|
|
|
|
請為您的語言下載 Erg
|
|
但是，外部庫可能不支持多種語言
|
|
|
|
## 只想更改記錄的某些屬性
|
|
|
|
```python
|
|
record: {.name = Str; .age = Nat; .height = CentiMeter}
|
|
{height; *rest} = record
|
|
mut_record = {.height = !height; *rest}
|
|
```
|
|
|
|
## 想要隱藏變量
|
|
|
|
使用 Erg 無法在相同范圍內進行遮蔽。但是，如果范圍發生變化，您可以重新定義它們(這是一種稱為實例塊的語法)
|
|
|
|
````python
|
|
## 獲取一個 T!-type 對象，最后將它作為 T 類型賦值給一個變量
|
|
x: T =
|
|
x: T! = foo()
|
|
x.bar!()
|
|
x.freeze()
|
|
````
|
|
|
|
## 想以某種方式重用最終類(不可繼承的類)
|
|
|
|
您可以創建一個包裝類。這就是所謂的構圖模式
|
|
|
|
```python
|
|
FinalWrapper = Class {inner = FinalClass}
|
|
FinalWrapper.
|
|
method self =
|
|
self::inner.method()
|
|
...
|
|
```
|
|
|
|
## 我想在1開頭枚舉
|
|
|
|
方法一:
|
|
|
|
```python
|
|
arr = [...]
|
|
for! arr.iter().enumerate(start := 1), i =>
|
|
...
|
|
```
|
|
|
|
method 2:
|
|
|
|
```python
|
|
arr = [...]
|
|
for! arr.iter().zip(1...) , i =>
|
|
...
|
|
```
|
|
|
|
## 想要測試一個(白盒)非公共 API
|
|
|
|
`foo.er` 中的私有 API 可在 `foo.test.er` 模塊中特別訪問
|
|
`foo.test.er` 模塊無法導入，因此它保持隱藏狀態
|
|
|
|
```python
|
|
# foo.er
|
|
private x = ...
|
|
```
|
|
|
|
```python
|
|
# foo.test.er
|
|
foo = import "foo"
|
|
|
|
@Test
|
|
'testing private' x =
|
|
...
|
|
y = foo::private x
|
|
...
|
|
```
|
|
|
|
## 在實現特征的方法時，會對未使用的變量發出警告
|
|
|
|
您可以將屬性設為私有并定義一個 getter
|
|
|
|
```python
|
|
C = Class {v = Int!}
|
|
C::
|
|
inc_v!(ref! self) = self::v.inc!()
|
|
...
|
|
C.
|
|
get_v(ref self): Int = self::v.freeze()
|
|
...
|
|
```
|
|
|
|
## 希望在類型系統上識別參數名稱
|
|
|
|
你可以使用`discard`或`_ = ...`
|
|
|
|
```python
|
|
T = Trait {.f = (Self, x: Int, s: Str) -> Int}
|
|
|
|
C = Class T
|
|
C|<: T|.
|
|
f self, x, s =
|
|
discard s # or _ = s
|
|
...
|
|
```
|
|
|
|
## 想要停止警告
|
|
|
|
Erg 中沒有停止警告的選項(這是設計使然)。請重寫你的代碼
|