使readonly属性可设置

Question

So basically I've come across some readonly properties on this one class that the writer of the class told me I could make settable for a specific task. Problem is, they get their value through manipulation most of the time, not directly from a private variable in the class.

Example:

public decimal? AccruedInterest
{
    get
    {
        if (this.Result != null)
        {
            return this.GetExchangedCurrencyValue(this.Result.AccruedInterest.GetValueOrDefault(decimal.Zero));
        }
        return null;
    }
}

So if I want to add a setter, I don't want to worry about setting that Result object because I'm not sure if on it's way back out it's going to be drawn correctly.

Would I be able to do something like this?

private decimal? _AccruedInterest;
public decimal? AccruedInterest
{
    get
    {
        if (this._AccruedInterest.HasValue)
        {
            return this._AccruedInterest.Value;
        }
        if (this.Result != null)
        {
            return this.GetExchangedCurrencyValue(this.Result.AccruedInterest.GetValueOrDefault(decimal.Zero));
        }
        return null;
    }
    set
    {
        this._AccruedInterest = value;
    }
}

Or do any of you see issues that could arise from this (besides the fact that it's now changeable)?

Answer 1

Well your only problem with this is if they set the value to be null and you want your property to return null rather than evaluate the if statement.

But you might not allow them to set null, in which case you should add a check in the setter.

set 
{ 
    if (value == null)
        throw new NullArgumentException("AccruedInterest");
    this._AccruedInterest = value;
}

If it is valid for them to set null, you probably need another boolean flag to tell if the value has been set.

private bool _accruedInterestSet;
private decimal? _accruedInterest;
public decimal? AccruedInterest
{
    get
    {
        if (this._accruedInterestSet)
        {
            return this._accruedInterest; //don't return .Value in case they set null
        }
        if (this.Result != null)
        {
            return this.GetExchangedCurrencyValue(this.Result.AccruedInterest.GetValueOrDefault(decimal.Zero))    ;
        }
        return null;
    }
    set
    {
        this._accruedInterestSet = true;
        this._AccruedInterest = value;
    }
}

Answer 2

我不知道它应该如何工作，但从语法上来说，我没有看到你的代码有任何问题。