Import std.core.error

Error

std.core.error

class

Public Class Error

The Class every error extends. Its first fields are Message, Cause, and Place, in that order, which the runtime reads and writes: Throw sets Place, unless the error has one from an earlier Throw, and top-level code that lets an error out shows all three, and its Cause's.

Examples

Function Age(text: String): Int Throws ArgumentError
    Local age = Int.Parse(text)
    If age == Null
        Throw ArgumentError(ArgumentErrorKind.INVALID, "'{text}' isn't an age", "age")
    End If

    Return age
End Function

Local error = ExpectThrows<ArgumentError>(Age("old"))
Expect(error?.Kind == ArgumentErrorKind.INVALID)
Expect(error?.Message == "'old' isn't an age")
Expect(error?.Name == "age")

// An error can say what it comes from.
Local wrapped = Error("couldn't load the level", IOError(IOErrorKind.NOT_FOUND, "no such file"))
Expect(wrapped.Cause?.Message == "no such file")

std/core/error.fb, line 66

Public Field Message: String field #

What went wrong, for people to read.
Public Field Cause: Error? field #

The error this one comes from, as when code that catches one throws its own.
Public ReadOnly Field Place: Place field #

Where it was first thrown.
Public New(message: String = "", cause: Error? = Null) constructor #

Makes an error that says message, from cause, if it has one.

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