diff options
Diffstat (limited to 'obnamlib/structurederror.py')
| -rw-r--r-- | obnamlib/structurederror.py | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/obnamlib/structurederror.py b/obnamlib/structurederror.py index 11e2491f..2fc04676 100644 --- a/obnamlib/structurederror.py +++ b/obnamlib/structurederror.py @@ -23,9 +23,21 @@ class StructuredError(Exception): '''A structured error exception. + A structured exception is meant to specify highly specific errors + in its type. Rather than getting a formatted message string as its + initialiser argument (e.g., "raise Exception('Something went + wrong')"), the message is an attribute of the StructuredError + subclass. Each message gets a separate sub-class: instead of a few + fairly generic exceptions, you're expected to create very specific + ones. For example, instead of, say, InputOutputError, you might + define FileNotFoundError, or even ConfigFileDoesNotExistError, as + well as ConfigFilePermissionDeniedError. More specific exceptions + make it easier to handle specific error cases, whether by catching + only specific ones, or by grepping log files for them. + Structured errors get a set of keyword arguments to the initialiser, and use them to fill in templates in a message string - provided by the exception class. In addition, each structured + attribute of the exception class. In addition, each structured exception has a unique ID, computed from the class name, which can be used, for example, as a user-visible error code. The ID is prepended to the message. The ID could also be used to look up |