Custom exceptions throwing error

[ShocKwav3]

Hi!

I have been stressing with this issue I am facing about my defined exception classes. As an example:
My custom defined class:

class SomeExceptionClass(Exception):
    _value = ''

    def __init__(self, value):
        self._value = value
        super().__init__()

    def __str__(self):
        return(repr(self._value))

I try to raise and handle it:

try:
    raise SomeExceptionClass('someMessage')
except SomeExceptionClass as e:
    print('oops')

I get the following error:

Traceback (most recent call last):
  File "boot.py", line 17, in <module>
TypeError: unsupported types for : 'TypeError', 'module'

I can not get my head around why is this issue happening. I tried searching but nothing fruitful came out. In fact, as I see similar post in the old micropython blog, it seemed it should work. I tried in wokwi simulator and it worked fine. Although, the simulator was using esp32 with micropython 1.19.1.

My board is a esp01 and micropython version is 1.20.0

I'd appreciate any help on this matter!

[shariltumin]

You can try this:

class myexception(Exception):
    def __init__(self, message):
        print('My Exception:')
        super().__init__('   '+message)

With that you can do:

>>> 
MPY: soft reboot
MicroPython v1.22.0-preview.1.g523284777.dirty on 2023-10-07; ESP8266 module with ESP8266
>>> 
paste mode; Ctrl-C to cancel, Ctrl-D to finish
=== class myexception(Exception):
===     def __init__(self, message):
===         print('My Exception:')
===         super().__init__('   '+message)
=== 
=== try:
===    raise myexception('not ok that')
=== except Exception as e:
===    print(e)
=== 
My Exception:
   not ok that
>>>  

[shariltumin]

What do you have on line 19 of the boot.py file?

[peterhinch]

It's OK here:

Python 3.10.12 (main, Jun 11 2023, 05:26:28) [GCC 11.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> class myexception(Exception):
...     def __init__(self, value):
...         super().__init__('   '+value)
... 
>>> try:
...     raise myexception('errorMessage')
... except myexception as e:
...     print('oops')
... 
oops
>>> 

[ShocKwav3]

What do you have on line 19 of the boot.py file?

@shariltumin bunch of commented code, I had it in project of mine. I did it in a single file now (please see my screenshot below) and still the same issue.

@peterhinch not sure what is going on... I have tried pasting the code in the REPL and it works, as I try to run it in the device I mean putting it in the main.py or boot.py I get the error. Please see my screenshot.

[shariltumin]

Can you try deleting line 8 (blank line)? There may be unprintable characters there.

And while you are in the REPL, try import main. Do you get the same error?

[ShocKwav3]

@shariltumin found even more strange thing. I kept no line break and it works.

Then I put the exception in a different location and try to run the code and it fails.

As seen in the screenshots, the main.py is in the root and the wifiexception is under exceptions folder.

What am I doing wrong here?

[jimmo]

@ShocKwav3 there's something about the way you're importing the exception from your exceptions directory... Back in the original post, the error is a bit subtle, but tells you that instead of importing SomeExceptionClass, you imported a module, but named it SomeExceptionClass. Perhaps you wrote

import something as SomeExceptionClass

??

Or perhaps something in exceptions/__init__.py is doing something strange?

The error you listed was:

Traceback (most recent call last):
  File "boot.py", line 17, in <module>
TypeError: unsupported types for : 'TypeError', 'module'

This means that it is trying to find an except block for an active TypeError, and it's trying to match it against something (SomeExceptionClass) which is of type module. The TypeError comes from trying to raise something that isn't an exception.

This is why it works when you run it directly (as what you're donig is definitely supported as @shariltumin and @peterhinch have pointed out), but not when you import the exception.

[ShocKwav3]

@jimmo Yes, you are right. I did have import something as SomeExceptionClass.

The TypeError comes from trying to raise something that isn't an exception.

I see what happened now... Thanks for the explanation and pointing out the mistake.

[shariltumin]

As Jim pointed out earlier, your import statement may be in error.

Since you have a subdirectory called "exceptions" and you put the wifiexception.py file there, please try.

from exceptions.wifiexception import wifiexception

The above tries to import wifiexception from "./exceptions/wifiexception.py".

I will do it differently. I will have a file "my_exceptions.py". I will declare all my all my exception classes in it. My import will be

from my_exceptions import myexception1, myexception2

It can be confusing to name a module file and a class in the modules with the same name.

[ShocKwav3]

@shariltumin Yes, the issue turned out to be the way I was importing it. Now I got it working. Thank you for taking time to debug this with me. Cheers!