.NET/C# try-catch-when syntax

Little scum · Posted on 10/18/2023 8:04:33 PM

Today, when I was looking at the source code of Serilog.AspNetCore.RequestLoggingMiddleware, I saw catch followed by the when keyword in the method, and then I never used the try-catch-when syntax.

when(C# reference):The hyperlink login is visible.

Use the context keyword when to specify the filter in the following contexts:

In the catch clause of the try-catch or try-catch-finally statement.
As a case guard in the switch statement.
as a case guard in the switch expression.

try-catch-when syntax

You can use the when keyword in the catch clause to specify a condition,This condition must be true for the handler to execute the handler for a particular exception。 The syntax is:

Login is visible.

Among them, expr is an expression whose calculation result is a boolean value. If the expression returns true, the exception handler is executed; If false is returned, it is not executed.

true: Enter the catch method to catch the exception.
false: Do not enter the current catch method, if there are other catches, it may enter other catch methods, if there are no other catches, the program will be exceptional.

The test is as follows:

Login is visible.

(End)

[Source] .NET/C# try-catch-when syntax

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