refactor exception handling #168

andlaus · 2023-07-31T08:13:22Z

These changes make it possible to continue the program execution if a deviation from the ODX specification was detected or a hard-coded assumption was violated. (If any of this happens, the behavior after that point is undefined.) The new mechanism consists of the following parts:

The odxtools.exceptions.strict_mode variable indicates whether program execution should be attempted to be continued if a violation is detected or not. The default is to not continue. Switching to non-strict mode can be achieved using
```
import odxtools

odxtools.exceptions.strict_mode = False
```
The odxraise() function raises an exception in strict mode and does nothing in non-strict mode. For type checkers, it looks like it always raises an exception.
The odxassert() function is very similar to the build-in assert statement, except that if the asserted condition is not met and if odxtools is in non-strict mode, program execution will continue. Unfortunately, this does not work well with type checkers as these do not consider the internal behavior of functions, so assert statements which's purpose is to narrow the type of a given object for the benefit of type checkers must be replaced by if...odxraise() constructs. E.g.
```
# prevent mypy from complaining
assert isinstance(x, int)
```
becomes
```
# prevent mypy from complaining
if not isinstance(x, int): odxraise()
```
In strict mode, the odxrequire() function raises an exception if its argument is None, in all other cases it passes through its argument without modifications. This allows to conveniently ensure that a given object was specified whilst convincing type checkers that it is not None. E.g., ensuring that a SHORT-NAME exists for an ElementTree node can be achieved using
```
short_name = odxrequire(et_element.findtext("SHORT-NAME"))
```

Andreas Lauser <[email protected]>, on behalf of MBition GmbH.
Provider Information

README.md

odxtools/admindata.py

odxtools/utils.py

examples/somersaultecu.py

odxtools/companydata.py

odxtools/exceptions.py

odxtools/nameditemlist.py

odxtools/exceptions.py

This commit makes it possible to continue the program execution if a deviation from the ODX specification was detected or a hard-coded assumption was violated. (If this is happens, the behavior is undefined.) The new mechanism consists of the following parts: - The `odxtools.exceptions.strict_mode` variable indicates whether program execution should be attempted to be continued if a violation is detected or not. The default is to not continue. Switching to non-strict mode can be achieved using ```python import odxtools odxtools.exceptions.strict_mode = False ``` - The `odxraise()` function raises an exception in strict mode and does nothing in non-strict mode. - The `odxassert()` function is very similar to the build-in `assert` statement, except that if the asserted condition is not met and if odxtools is in non-strict mode, program execution will continue. Unfortunately, this does not work well with type checkers as these do not consider the internal behaviour of functions, so `assert` statements which's purpose is to instruct type checkers that an object is of a given type must be replaced by `if...odxraise()` constructs. E.g. ```python # prevent mypy from complaining assert isinstance(x, int) ``` becomes ```python # prevent mypy from complaining if not isinstance(x, int): odxraise() ``` - In strict mode, the `odxrequire()` function raises an exeption if its argument is `None`, in all other cases it passes through its argument without modifications. This allows to conveniently ensure that a given object was specified whilst convincing type checkers that it is not `None`. E.g., ensuring that a `SHORT-NAME` exists for an ElementTree node can be achieved using ```python short_name = odxrequire(et_element.findtext("SHORT-NAME") ``` Signed-off-by: Andreas Lauser <[email protected]> Signed-off-by: Christian Hackenbeck <[email protected]>

thanks! Signed-off-by: Andreas Lauser <[email protected]> Signed-off-by: Christian Hackenbeck <[email protected]>

andlaus requested a review from kayoub5 July 31, 2023 08:13