DIP33
This DIP is currently under construction. Please come back later.
| Title: | A new exception hierarchy |
|---|---|
| DIP: | 33 |
| Version: | 1 |
| Status: | Draft |
| Created: | 2013-04-01 |
| Last Modified: | 2013-04-01 |
| Author: | Lars T. Kyllingstad |
| Links: |
Contents
[hide]Abstract
This is a proposal for a new exception hierarchy for Druntime and Phobos.
Rationale
Overview
The following is an outline of the exceptions in the hierarchy, and how they are related to each other. Deeper levels are subclasses of those above.
ThrowableErrorAssertErrorInvalidArgumentErrorRangeError
ExceptionConversionExceptionExceptionEncodingExceptionFilesystemExceptionIOExceptionNetworkException
ParseExceptionDocParseException
ProcessExceptionSystemExceptionErrnoExceptionWinAPIException
ThreadException
OutOfMemory
Top-level classes
Error
class Error : Throwable { }
Error and its subclasses are used to signal programming errors. If an Error is thrown, it means that there is something wrong with how the program is constructed. Examples include array index out of bounds, invalid function arguments, etc. Errors can always be avoided by design.
Exception
class Exception : Throwable { }
Exception and its descendants are used to signal normal runtime errors. These are exceptional circumstances that the programmer cannot be expected to avoid by design. Examples include file not found, problems with parsing a document, system errors, etc.
OutOfMemory
class OutOfMemory : Throwable { }
This exception is thrown on an attempt to allocate more memory than what is currently available for the program. Strictly speaking, this is not an Error, as the programmer cannot reasonably be expected to check memory availability before each allocation. However, is not desirable to catch it along with normal Exceptions either, as an OOM condition requires special treatment. Therefore, this DIP places OutOfMemory at the top level of the hierarchy.
Copyright
This document has been placed in the Public Domain.
