Question

我在使用“自治”时,打过一个有名的论据非常合适的地方:

.ForMember(s => s.MyProperty, opt => opt.MapFrom(s => BuildMyProperty(s, isAdvanced: false)))

但汇编者在我席上:

表达的树木不得包含一个有名的辨识。

因此,我不得不再次谈谈:

.ForMember(s => s.MyProperty, opt => opt.MapFrom(s => BuildMyProperty(s, false)))

是否有任何人知道,汇编者为何在这一局势中不提出有名的论点?

Answer 1

考虑如下:

static int M() { Console.Write("M"); return 1; }
static int N() { Console.Write("N"); return 2; }
static int Q(int m, int n) { return m + n; }
...
Func<int> f = ()=>Q(n : N(), m: M());
Expression<Func<int>> x = ()=>Q(n : N(), m: M());
Func<int> fx = x.Compile();
Console.WriteLine(f());
Console.WriteLine(fx());

你们同意,我希望,最后两条路线必须完全相同,正确吗? 印刷NM3。

现在,树木图书馆所说的话是什么,你希望树林的转化能够确保这一点? 无。因此,我们面临以下选择:

Implement the feature in the expression tree library. Add a transformation in the expression tree lowering engine that preserves the order of execution of the named arguments. Implement code in the Compile method that takes the execution order into account.
Make x = ()=>Q(n : N(), m: M()); actually be implemented as x = ()=>Q(M(), N()); and be incompatible with the non-expression-tree version.
Disallow named arguments in expression trees. Implement an error message to that effect.

(1) 是冰,但代价高昂。 (2) 是非开端者;我们可以本着良知引入这种“cha”。 (3) 价格低廉,但令人不快。

我们选择了(3)。

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