MethodVsProperty.txt
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20191212

https://docs.microsoft.com/en-us/previous-versions/dotnet/netframework-1.1/bzwdh01d(v=vs.71)?redirectedfrom=MSDN#cpconpropertyusageguidelinesanchor1

Use a method when:

The operation is a conversion, such as Object.ToString.
The operation is expensive enough that you want to communicate to the user that they should consider caching the result.
Obtaining a property value using the get accessor would have an observable side effect.
Calling the member twice in succession produces different results.
The order of execution is important. Note that a type's properties should be able to be set and retrieved in any order.
The member is static but returns a value that can be changed.
The member returns an array. Properties that return arrays can be very misleading. Usually it is necessary to return a copy of the internal array so that the user cannot change internal state. This, coupled with the fact that a user can easily assume it is an indexed property, leads to inefficient code. In the following code example, each call to the Methods property creates a copy of the array. As a result, 2n+1 copies of the array will be created in the following loop.
使用 method 的時機(不建議使用 property):
1. 轉換型別. 例如 Object.ToString.
2. 作業負荷較重. 使用者必須注意自行保留運算結果.
3. 交互影響. 當使用 get 時, 導致交互影響的結果.
4. 重複呼叫會導致不同的結果.
5. 執行順序很重要時. 設定或讀取 property 應可以任何順序執行.
6. 成員為靜態 static, 但是回傳值可以變更時.
7. 回傳陣列. property 回傳陣列容易造成混亂. 通常必須是回傳陣列副本, 不讓外部影響內部的狀態. 但若使用副本的話, 使用者會誤用為 indexed property, 導致無效率的程式碼