Types -of error and recovery

diff -r ebc84c812384 -r 46218c8b8afa Symbian3/PDK/Source/GUID-40671EEC-DACC-5F0B-978C-2794FB206E62.dita --- a/Symbian3/PDK/Source/GUID-40671EEC-DACC-5F0B-978C-2794FB206E62.dita Thu Mar 11 15:24:26 2010 +0000 +++ b/Symbian3/PDK/Source/GUID-40671EEC-DACC-5F0B-978C-2794FB206E62.dita Thu Mar 11 18:02:22 2010 +0000 @@ -1,47 +1,47 @@ - - - - - -Types -of error and recoveryDescribes error conditions and how errors are handled. -

Error conditions can be divided into three broad categories:

program errors, such -as an attempt to access an element beyond the bounds of an array or buffer
environment errors, -such as insufficient memory, insufficient disk space, or other missing resources
user errors, such as -an attempt to enter bad data in a dialog, an invalid action in, say, a word -processor, or bad syntax in a source file

Program errors are checked by asserts (__ASSERT_DEBUG macro), -and are signalled by a panic. Recovery from such errors involves re-writing -part of the program that contained the error.

Environment and user errors can be handled in broadly two ways:

If they can be detected -before an action is performed, then a return value other than KErrNone is -a convenient means to signal the error.

This method is simple to program, -and cleanup requirements, if they exist at all, are often easy to identify -and handle.
Alternatively, the program -can use the exception handling and cleanup techniques discussed in this section.

This -method is more appropriate when the detection of an error occurs deep inside -the processing of a requested action: if the error return value method were -used, every function would have to return such an error and cleanup requirements -would have to be handled for virtually every function call. The logic becomes -repetitive and it’s easier to incorporate it into an exception-handling scheme.

When programming for possible environment or user error conditions, bear -in mind both approaches for handling them, and choose the most suitable one.

Applications must perform proper cleanup when an exception occurs, because -they are designed to run for long periods (months or even years) without interruption -or system re-boot.

+ + + + + +Types +of error and recoveryDescribes error conditions and how errors are handled. +

Error conditions can be divided into three broad categories:

program errors, such +as an attempt to access an element beyond the bounds of an array or buffer
environment errors, +such as insufficient memory, insufficient disk space, or other missing resources
user errors, such as +an attempt to enter bad data in a dialog, an invalid action in, say, a word +processor, or bad syntax in a source file

Program errors are checked by asserts (__ASSERT_DEBUG macro), +and are signalled by a panic. Recovery from such errors involves re-writing +part of the program that contained the error.

Environment and user errors can be handled in broadly two ways:

If they can be detected +before an action is performed, then a return value other than KErrNone is +a convenient means to signal the error.

This method is simple to program, +and cleanup requirements, if they exist at all, are often easy to identify +and handle.
Alternatively, the program +can use the exception handling and cleanup techniques discussed in this section.

This +method is more appropriate when the detection of an error occurs deep inside +the processing of a requested action: if the error return value method were +used, every function would have to return such an error and cleanup requirements +would have to be handled for virtually every function call. The logic becomes +repetitive and it’s easier to incorporate it into an exception-handling scheme.

When programming for possible environment or user error conditions, bear +in mind both approaches for handling them, and choose the most suitable one.

Applications must perform proper cleanup when an exception occurs, because +they are designed to run for long periods (months or even years) without interruption +or system re-boot.

\ No newline at end of file