F#校验算法范围

本文介绍了F#校验算法范围的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

F#允许通过打开Checked模块来使用检查的算术，该模块将标准运算符重新定义为要检查的运算符，例如:

F# allows to use checked arithmetics by opening Checked module, which redefines standard operators to be checked operators, for example:

open Checked let x = 1 + System.Int32.MaxValue // overflow

将导致算术溢出异常.

但是，如果我想在较小的范围内使用检查的算术，例如C#允许使用关键字checked:

But what if I want to use checked arithmetics in some small scope, like C# allows with keyword checked:

int x = 1 + int.MaxValue; // ok int y = checked { 1 + int.MaxValue }; // overflow

如何通过打开Checked模块来控制操作符的重新定义范围或使其更小?

How can I control the scope of operators redefinition by opening Checked module or make it smaller as possible?

推荐答案

您始终可以定义一个单独的运算符，或者使用阴影，或者使用parens为临时阴影创建内部范围:

You can always define a separate operator, or use shadowing, or use parens to create an inner scope for temporary shadowing:

let f() = // define a separate operator let (+.) x y = Checked.(+) x y try let x = 1 +. System.Int32.MaxValue printfn "ran ok" with e -> printfn "exception" try let x = 1 + System.Int32.MaxValue printfn "ran ok" with e -> printfn "exception" // shadow (+) let (+) x y = Checked.(+) x y try let x = 1 + System.Int32.MaxValue printfn "ran ok" with e -> printfn "exception" // shadow it back again let (+) x y = Operators.(+) x y try let x = 1 + System.Int32.MaxValue printfn "ran ok" with e -> printfn "exception" // use parens to create a scope ( // shadow inside let (+) x y = Checked.(+) x y try let x = 1 + System.Int32.MaxValue printfn "ran ok" with e -> printfn "exception" ) // shadowing scope expires try let x = 1 + System.Int32.MaxValue printfn "ran ok" with e -> printfn "exception" f() // output: // exception // ran ok // exception // ran ok // exception // ran ok

最后，另请参见--checked+编译器选项:

Finally, see also the --checked+ compiler option:

msdn.microsoft/en -us/library/dd233171(VS.100).aspx