与 C# 中的块等效？
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With block equivalent in C#?
提问by Dan Appleyard
I know VB.Net and am trying to brush up on my C#. Is there a With block equivalent in C#?
我知道 VB.Net 并且正在尝试复习我的 C#。C# 中是否有等价的 With 块？
Thanks
谢谢
回答by Guulh
No, there is not.
不，那里没有。
回答by BBetances
You could use the argument accumulator pattern.
您可以使用参数累加器模式。
Big discussion about this here:
关于这里的大讨论：
http://blogs.msdn.com/csharpfaq/archive/2004/03/11/87817.aspx
http://blogs.msdn.com/csharpfaq/archive/2004/03/11/87817.aspx
回答by mlennox
hmm. I have never used VB.net in any depth, so I'm making an assumption here, but I think the 'using' block might be close to what you want.
唔。我从来没有深入使用过 VB.net，所以我在这里做一个假设，但我认为“使用”块可能接近你想要的。
using defines a block scope for a variable, see the example below
using 定义了一个变量的块作用域，见下面的例子
using ( int temp = someFunction(param1) ) {
temp++; // this works fine
}
temp++; // this blows up as temp is out of scope here and has been disposed
Here is an article from Microsoft that explains a bit more
EDIT: yeah, this answer is wrong - the original assumption was incorrect. VB's 'WITH' is more like the new C# object initialisers:
编辑：是的，这个答案是错误的 - 最初的假设是错误的。VB 的“WITH”更像是新的 C# 对象初始值设定项：
var yourVariable = new yourObject { param1 = 20, param2 = "some string" };
回答by Timothy Carter
About 3/4 down the page in the "Using Objects" section:
在“使用对象”部分的页面下方约 3/4 ：
VB:
VB：
With hero
.Name = "SpamMan"
.PowerLevel = 3
End With
C#:
C＃：
//No "With" construct
hero.Name = "SpamMan";
hero.PowerLevel = 3;
回答by Jon Skeet
Although C# doesn't have any direct equivalent for the general case, C# 3 gain object initializer syntax for constructor calls:
尽管 C# 对于一般情况没有任何直接等效项，但 C# 3 为构造函数调用获得了对象初始值设定项语法：
var foo = new Foo { Property1 = value1, Property2 = value2, etc };
See chapter 8 of C# in Depth for more details - you can download it for free from Manning's web site.
有关更多详细信息，请参阅 C# 深入了解的第 8 章 - 您可以从Manning 的网站免费下载。
(Disclaimer - yes, it's in my interest to get the book into more people's hands. But hey, it's a free chapter which gives you more information on a related topic...)
（免责声明 - 是的，让更多人掌握这本书符合我的利益。但是，嘿，这是一个免费章节，可为您提供有关相关主题的更多信息......）
回答by Gulzar Nazim
This is what Visual C# program manager has to say: Why doesn't C# have a 'with' statement?
这就是 Visual C# 程序管理器必须说的： 为什么 C# 没有“with”语句？
Many people, including the C# language designers, believe that 'with' often harms readability, and is more of a curse than a blessing. It is clearer to declare a local variable with a meaningful name, and use that variable to perform multiple operations on a single object, than it is to have a block with a sort of implicit context.
许多人，包括 C# 语言设计者，都认为“with”通常会损害可读性，与其说是一种祝福，不如说是一种诅咒。用有意义的名称声明一个局部变量，并使用该变量对单个对象执行多个操作，这比使用具有某种隐式上下文的块更清晰。
回答by RTPeat
As the Visual C# Program Manager linked above says, there are limited situations where the With statement is more efficient, the example he gives when it is being used as a shorthand to repeatedly access a complex expression.
正如上面链接的 Visual C# 程序管理器所说，With 语句在有限的情况下效率更高，他给出的示例是当它被用作重复访问复杂表达式的速记时。
Using an extension method and generics you can create something that is vaguely equivalent to a With statement, by adding something like this:
使用扩展方法和泛型，您可以通过添加以下内容来创建与 With 语句大致等效的内容：
public static T With<T>(this T item, Action<T> action)
{
action(item);
return item;
}
Taking a simple example of how it could be used, using lambda syntax you can then use it to change something like this:
举一个如何使用它的简单示例，使用 lambda 语法，您可以使用它来更改如下内容：
updateRoleFamily.RoleFamilyDescription = roleFamilyDescription;
updateRoleFamily.RoleFamilyCode = roleFamilyCode;
To this:
对此：
updateRoleFamily.With(rf =>
{
rf.RoleFamilyDescription = roleFamilyDescription;
rf.RoleFamilyCode = roleFamilyCode;
});
On an example like this, the only advantage is perhaps a nicer layout, but with a more complex reference and more properties, it could well give you more readable code.
在这样的示例中，唯一的优势可能是更好的布局，但是有了更复杂的引用和更多的属性，它可以为您提供更易读的代码。
回答by Sean
Sometimes you can get away with doing the following:
有时，您可以通过执行以下操作来逃脱惩罚：
var fill = cell.Style.Fill;
fill.PatternType = ExcelFillStyle.Solid;
fill.BackgroundColor.SetColor(Color.Gray);
fill.PatternColor = Color.Black;
fill.Gradient = ...
(Code sample for EPPLus @ http://zeeshanumardotnet.blogspot.com)
（EPPLus 的代码示例@ http://zeeshanumardotnet.blogspot.com）
回答by IlPADlI
I was using this way:
我是这样使用的：
worksheet.get_Range(11, 1, 11, 41)
.SetHeadFontStyle()
.SetHeadFillStyle(45)
.SetBorders(
XlBorderWeight.xlMedium
, XlBorderWeight.xlThick
, XlBorderWeight.xlMedium
, XlBorderWeight.xlThick)
;
SetHeadFontStyle / SetHeadFillStyle is ExtMethod of Rangelike below:
SetHeadFontStyle / SetHeadFillStyle 是Range 的ExtMethod，如下所示：
public static Range SetHeadFillStyle(this Range rng, int colorIndex)
{
//do some operation
return rng;
}
do some operation and return the Rangefor next operation
做一些操作并返回下一个操作的范围
it's look like Linq :)
它看起来像 Linq :)
but now still can't fully look like it -- propery set value
但现在仍然不能完全像它 - 属性设置值
with cell.Border(xlEdgeTop)
.LineStyle = xlContinuous
.Weight = xlMedium
.ColorIndex = xlAutomatic
回答by Wouter Schut
Most simple syntax would be:
最简单的语法是：
{
var where = new MyObject();
where.property = "xxx";
where.SomeFunction("yyy");
}
{
var where = new MyObject();
where.property = "zzz";
where.SomeFunction("uuu");
}
Actually extra code-blocks like that are very handy if you want to re-use variable names.
实际上，如果您想重用变量名，像这样的额外代码块非常方便。
