C++ Exceptions

[gswifort]

To make working with C++ exceptions easier I added tools to translate general C++ exceptions (RuntimeError) to specific types. You can see the implementation here.
Usage looks like this:

text = Db.Text()
text_id = db.addToModelspace(text)
with cast_to_arx_exception:
    Db.Text(text_id, Db.OpenMode.kForRead)  # raises pyrx.exceptions.eWasOpenForWrite

I wonder if I should stick to this path or if you have a better idea..? Maybe you want to implement something similar in C++?

[CEXT-Dan]

This is what I am currently using for exceptions, it appears to be limited to RuntimeError and a message
https://boostorg.github.io/python/doc/html/reference/high_level_components/boost_python_exception_translato.html

[CEXT-Dan]

That's pretty cool though.
for support requests, I'll want to have the C++ exception message, Acad::ErrorStatus, function, Line, File.

[gswifort]

Yes, in the example I only showed the error type, but the message is also passed so the message is complete.

[gswifort]

See if this will be helpful.

https://stackoverflow.com/questions/2261858/boostpython-export-custom-exception

[CEXT-Dan]

Okay, great idea, seems very useful!
I’ll have a look at this, though I have a couple other tasks in front

[CEXT-Dan]

I was able to get the sample from stack overflow working (the one by David Faure towards the end). I don’t know if I like it as it’s kind of a monkey patch.

The sample attaches an object ‘cause’, which I renamed ctx, short for context to the built-in exception.
There’s no IntelliSense since it’s a patch, maybe this can be done manually

ctx has properties

err.ctx.fullmessage
err.ctx.message
err.ctx.code

example:

from pyrx_imp import Ap, Db, Ed, Ge, Gi, Gs, Rx

def PyRxCmd_edoit1():
    try:
        db = Db.curDb()
        text = Db.Text()
        text_id = db.addToModelspace(text)
        Db.Text(text_id, Db.OpenMode.kForRead)
    except Db.ErrorStatusException as err:
        match err.ctx.code:
            case Db.ErrorStatus.eWasOpenForWrite:
                print("caught eWasOpenForWrite")
            case Db.ErrorStatus.eOnLockedLayer:
                print("caught eOnLockedLayer")
            case _:
                print("caught {}".format(err.ctx.code))
    except Exception as err:
        print(err)
        
def PyRxCmd_edoit2():
    try:
        db = Db.curDb()
        text = Db.Text()
        text_id = db.addToModelspace(text)
        Db.Text(text_id, Db.OpenMode.kForRead)
    except Db.ErrorStatusException as err:
        match err.ctx.message:
            case 'eWasOpenForWrite':
                print("caught eWasOpenForWrite")
            case 'eOnLockedLayer':
                print("caught eOnLockedLayer")
            case _:
                print("caught {}".format(err.ctx.code))
    except Exception as err:
        print(err)

def PyRxCmd_doit1():
    try:
        db = Db.curDb()
        text = Db.Text()
        text_id = db.addToModelspace(text)
        Db.Text(text_id, Db.OpenMode.kForRead)
    except Db.ErrorStatusException as err:
        print(1,err.ctx.fullmessage)
    except Exception as err:
        print(4,err)
        
def PyRxCmd_doit4():
    try:
        db = Db.curDb()
        text = Db.Text()
        text_id = db.addToModelspace(text)
        Db.Text(text_id, Db.OpenMode.kForRead)
    except Exception as err:
        print(4,err)

[CEXT-Dan]

That’s what the first example attempts to do that, but apparently it does not work with Python 3
Also, I think I would have to maintain a static state, at that point it would be the same as adding global last error function

‘ctx’ is an actual object that gets garbage collected so there’s no memory leak
Maybe there’s a better name for ctx?

[gswifort]

No, the ctx name is ok.

[CEXT-Dan]

Another, maybe better approach is to assign a tuple to the exception with function
PyErr_SetObject

example

def PyRxCmd_doit5():
    try:
        db = Db.curDb()
        text = Db.Text()
        text_id = db.addToModelspace(text)
        Db.Text(text_id, Db.OpenMode.kForRead)
    except Db.ErrorStatusException as err:
        es, sm, fm = err.args
        
        print(es)
        print(sm)
        print(fm)
        
    except Exception as err:
        print(err)

I think I could attach a dict, this would prevent issues with ordering

[gswifort]

Assigning a dict to args can be confusing, maybe namedtuple?

[CEXT-Dan]

actually, I figured out how to add the methods directly

def PyRxCmd_doit1():
    try:
        db = Db.curDb()
        text = Db.Text()
        text_id = db.addToModelspace(text)
        Db.Text(text_id, Db.OpenMode.kForRead)
    except Db.ErrorStatusException as err:
        print(err.code)
        print(err.message)
        print(err.fullmessage)
    except Exception as err:
        print(err)