https://github.com/wk-j/fsharp-extension-property
https://github.com/wk-j/fsharp-extension-property
Last synced: 26 days ago
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- Host: GitHub
- URL: https://github.com/wk-j/fsharp-extension-property
- Owner: wk-j
- Created: 2016-05-02T10:44:55.000Z (almost 9 years ago)
- Default Branch: master
- Last Pushed: 2016-05-02T13:17:47.000Z (almost 9 years ago)
- Last Synced: 2025-02-08T18:22:55.566Z (3 months ago)
- Language: F#
- Size: 1.95 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
## Extension Method / Property
### เขียน Extension method เพิ่มใช้งานใน `F#`
```fsharp
[]
module ExtensionMethodOnlyInFSharp =
type System.String with
member this.IsFSharp() = this = "F#"
member this.``IsF#`` with get() = this = "F#"
printfn "Equal to F#? %A" ("F#".IsFSharp())
printfn "Equal to F#? %A" ("F#".``IsF#``)
```
- สร้างสร้าง Extension method / property ของ `String` โดยใช้ Keyword `with`
- `IsFSharp()` เป็น Extension method เรียกใช้ผ่าน `.IsFSharp()`
- `IsF#` เป็น Extension property เรียกใช้ผ่าน `.IsF#` โดยไม่ต้องเติม `()`
### เขียน Extension method ให้สามารถเรียกใช้งานจาก `C#`
```fsharp
[]
module ExtensionMethodForCSharp =
[]
let IsFSharp(str: string) = str = "F#"
[]
let ``IsF#``(str: string) = IsFSharp str
```
- ต้องเพิ่ม `[]`
- Extension property `IsF#` ไม่สามารถเรียกใช้งานจาก `C#` ได้
### Extension method ใน Array
```fsharp
type 'T``[]`` with
member this.MyExtension with get() = "My Extension"
let x: string array = [||]
x.MyExtension
```
### Extension property กับ Literal type
```fsharp
type System.Int32 with
member x.Months = DateTime.Today.AddMonths(x) - DateTime.Today
member x.Years = DateTime.Today.AddYears(x) - DateTime.Today
type System.Double with
member x.Days = DateTime.Today.AddDays(x) - DateTime.Today
type System.TimeSpan with
member x.Ago = DateTime.Now.Add(-x)
member x.FromNow = DateTime.Now.Add(x)
member x.FromToday = DateTime.Today.Add(x)
let _20YearAgo = DateTime.Now - 20 .Years
let _50YearAgo = 50 .Years.Ago
let _100YearFromNow = DateTime.Now + 100 .Years
```
- สามารถใช้ `Space .` แทน `().`
- เช่น ใช้ `100 .Years` แทน `(100).Years`
## Link
- http://blog.stermon.com/articles/2014/03/06/fsharp-surprisingly-expressive
- http://apollo13cn.blogspot.com/2012/08/f-extension-methods.html