Do I completely not understand what is nothrow or why I can't make function nothrow with just catching StdioException?

This doesn't work

nothrow void hello() {
  try {
    writeln("Hello, World!")
  } catch (StdioException) {}
}

This doest work

nothrow void hello() {
  try {
    writeln("Hello, World!")
  } catch (Exception) {}
}

On Monday, 21 February 2022 at 10:49:13 UTC, partypooper wrote:

nothrow void hello() {
  try {
    writeln("Hello, World!")
  } catch (StdioException) {}
}

nothrow void hello() {
  try {
    writeln("Hello, World!")
  } catch (Exception) {}
}

I believe it's because it can throw ConvException as well ;)

On Monday, 21 February 2022 at 10:53:56 UTC, Basile B. wrote:

nothrow void hello() {
  try {
    writeln("Hello, World!")
  } catch (StdioException) {}
}

nothrow void hello() {
  try {
    writeln("Hello, World!")
  } catch (Exception) {}
}

However you're totally right to open a discussion, the documentation is innacurate:

in https://dlang.org/phobos/std_stdio.html#.writeln

just StdioException is mentioned ;)

On Monday, 21 February 2022 at 10:53:56 UTC, Basile B. wrote:

nothrow void hello() {
  try {
    writeln("Hello, World!")
  } catch (StdioException) {}
}

nothrow void hello() {
  try {
    writeln("Hello, World!")
  } catch (Exception) {}
}

more likely UTFException actually

On Monday, 21 February 2022 at 10:49:13 UTC, partypooper wrote:

nothrow void hello() {
  try {
    writeln("Hello, World!")
  } catch (StdioException) {}
}

nothrow void hello() {
  try {
    writeln("Hello, World!")
  } catch (Exception) {}
}

https://issues.dlang.org/show_bug.cgi?id=22800

On Monday, 21 February 2022 at 10:49:13 UTC, partypooper wrote:

D does not have checked exceptions like Java, so the compiler doesn't have anyway to verify that any function you call won't throw a given exception. You have to catch Exception to satisfy the nothrow requirement.

On Monday, 21 February 2022 at 10:58:26 UTC, Basile B. wrote:

Additionaly catching UTF and Conv exceptions doesn't help.

On Monday, 21 February 2022 at 11:05:42 UTC, partypooper wrote:

Yeah there must be another one then. Something actionnable is the documentation.

On Monday, 21 February 2022 at 11:04:46 UTC, Mike Parker wrote:

Oh, that's explain it.
So with such behavior there is no reason at all to make make function nothrow, if it uses throw functions in its body? And as much as I already know compliler can deduce and automatically adds nothrow to all functions which do not throw exceptions. Right?

On Monday, 21 February 2022 at 11:07:55 UTC, Basile B. wrote:

What about Mike Parker answer?