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How to avoid duplicates when python multiple except executes the same method?

I have the code block like below:
try:
method()
except ErrorType1:
todo()
return
except ErrorType2 as e:
todo()
raise e
Basically for the two error types, I need to execute todo() first, then either return or raise e. Is it possible to just write todo() once? I was thinking using finally but don't think that actually works.

You could catch both exceptions in one except clause, execute todo and then decide to do based on the exception type:
try:
method()
except (ErrorType1, ErrorType2) as e:
todo()
if isinstance(e, ErrorType1):
return
raise
Note - as pointed out by #ShadowRanger in the comments to the question - you should just use raise to re-raise the existing exception, using raise e will raise a second copy of it, resulting in the traceback including the line with raise e on it as well as the line where the original error occurred.

If you have an common set of instructions (either encapsulated as a function or series of functions) that must be executed as part of an exception handling, consider using a context manager to encapsulate the common bits. The following two results in identical outcome, albeit with different construction (one using try..finally, the other using try..except).
from contextlib import contextmanager
#contextmanager
def context1(method):
print("starting context1")
completed = False
try:
yield method()
completed = True
finally:
if completed:
commit()
else:
rollback()
print("finished")
#contextmanager
def context2(method):
print("starting context2")
try:
yield method()
except Exception:
rollback()
raise
else:
commit()
print("finished")
The latter one will not be able to deal with KeyboardInterrupt or other exceptions that subclass off BaseException, so for certain use case this is not exactly ideal, though it is included to follow suite of the question. The first one is more of a response to the fact that you never appeared to have tried using finally, but rather simply thinking it does not actually works, and thus provided to show it can be used to achieve your goal (where only todo() in the question is executed if failure, through the use of a boolean variable).
In both cases, note how the common control flow is fully encapsulated inside the context manager, and usage is fairly straightforward like so such that all the unique extra cases can be done with another try..except block around the with context block.
try:
with context1(f) as result:
pass # or use the result to do something
except Exception: ...
# all the special unique cases be handled here.
To complete demo, more code is below; the commit and rollback functions I defined the following:
def commit():
print("commit")
def rollback():
print("rollback")
Now to test it, I defined the following helpers:
from functools import partial
class ErrorType1(Exception):
pass
class ErrorType2(Exception):
pass
def raise_e(e):
raise e
subject = [
object,
partial(raise_e, ErrorType1),
partial(raise_e, ErrorType2),
]
With the tests defined as such (replace context1 with context2 for the other demonstration):
for f in subject:
try:
with context1(f) as result:
print('done - got result %r' % result)
except ErrorType2:
print("ErrorType2 will be raised")
# raise # uncomment to actually re-raise the exception
except Exception as e:
print("Exception trapped: %r raised by %r" % (e, f))
Note the output of both the above should look about like so (aside from context1 vs context2):
starting context1
done - got result <object object at 0x7f20ccd3e180>
commit
finished
starting context1
rollback
Exception trapped: ErrorType1() raised by functools.partial(<function raise_e at 0x7f20ccb30af0>, <class '__main__.ErrorType1'>)
starting context1
rollback
ErrorType2 will be raised

Exception handling: evaluate multiple statements

Scraping webpages with Python 3.8, Selenium and BeautifulSoap, I would like to remove or alter some elements. Since not all pages contain the respective elements, I have to catch exceptions:
try:
soup.find('aside', id="post").decompose()
except Exception:
pass
try:
soup.find('footer', id="footer").decompose()
except Exception:
pass
try:
soup.find(class_="myclass")["class"] = ''
except Exception:
pass
There is a lot of repetition in this code (my list of statements is even longer), so I tried to build a block:
try:
soup.find('aside', id="post").decompose()
soup.find('footer', id="footer").decompose()
soup.find(class_="myclass")["class"] = ''
except Exception:
pass
But this isn't what I want to achieve, because if first statement doesn't catch a match, then the following statements aren't evaluated at all.
What's a good, pythonic and elegant way to execute/evaluate all statements? I read, that using pass is bad practice also. Maybe try isn't the correct thing here at all and would be better off using something like isset() in PHP (but in python I don't know the eqivalent)?

Not an ideal solution, but you can decorate functions to ignore exceptions and then use decorated functions instead of originals:
from functools import wraps
def exceptions_ignored(callee):
#wraps(callee)
def _ignore(*args, **kwargs):
try:
return callee(*args, **kwargs)
except Exception:
pass
return _ignore
mydivmod = exceptions_ignored(divmod)
# or define it as
# #exceptions_ignored
# def mydivmod(n, d):
# return divmod(n, d)
mydivmod(5, 0)

python - move on after exception and raise it afterwards

I think this should be a bit tricky but somehow feasible, but I need help.
I'd like to execute two functions from within my main() func.
I'd like to be able to catch exceptions from the two separately, but still being able to execute both and get the result of at least one of them if the other raises an exception.
Let's say I have:
def foo():
raise TypeError
def bar():
return 'bar'
If I do (adapted from here):
def multiple_exceptions(flist):
for f in flist:
try:
return f()
except:
continue
def main():
multiple_exceptions([foo, bar])
main()
main() would return 'bar', but I'd like to be able to still throw the exception from foo() after all. This way, I would still have the result of one of my functions and the information on the error occurred in the other.

You can capture and store the exceptions using 'as', e.g.:
try:
raise Exception('I am an error!')
print('The poster messed up error-handling code here.') #should not be displayed
except Exception as Somename:
print(Somename.message)
# you'll see the error message displayed as a normal print result;
# you could do print(stuff, file=sys.stderr) to print it like an error without aborting
print('Code here still works, the function did not abort despite the error above')
...or you can do:
except Exception as Somename:
do_stuff()
raise Somename

Thanks for the comments.
I solved by doing this:
def multiple_exceptions(flist):
exceptions = []
for f in flist:
try:
f()
except Exception as e:
exceptions.append(e.message)
continue
return exceptions
def main():
multiple_exceptions([foo, bar])
error_messages = main() # list of e.messages occurred (to be raised whenever I want)
Then I can raise my exception like e.g. raise Exception(error_messages[0]) (I only care about the first in this case let's say).

Better way to use try except block

I have a requirement to execute multiple Python statements and few of them might fail during execution, even after failing I want the rest of them to be executed.
Currently, I am doing:
try:
wx.StaticBox.Destroy()
wx.CheckBox.Disable()
wx.RadioButton.Enable()
except:
pass
If any one of the statements fails, except will get executed and program exits. But what I need is even though it is failed it should run all three statements.
How can I do this in Python?

Use a for loop over the methods you wish to call, eg:
for f in (wx.StaticBox.Destroy, wx.CheckBox.Disable, wx.RadioButton.Enable):
try:
f()
except Exception:
pass
Note that we're using except Exception here - that's generally much more likely what you want than a bare except.

If an exception occurs during a try block, the rest of the block is skipped. You should use three separate try clauses for your three separate statements.
Added in response to comment:
Since you apparently want to handle many statements, you could use a wrapper method to check for exceptions:
def mytry(functionname):
try:
functionname()
except Exception:
pass
Then call the method with the name of your function as input:
mytry(wx.StaticBox.Destroy)

I would recommend creating a context manager class that suppress any exception and the exceptions to be logged.
Please look at the code below. Would encourage any improvement to it.
import sys
class catch_exception:
def __init__(self, raising=True):
self.raising = raising
def __enter__(self):
pass
def __exit__(self, type, value, traceback):
if issubclass(type, Exception):
self.raising = False
print ("Type: ", type, " Log me to error log file")
return not self.raising
def staticBox_destroy():
print("staticBox_destroy")
raise TypeError("Passing through")
def checkbox_disable():
print("checkbox_disable")
raise ValueError("Passing through")
def radioButton_enable():
print("radioButton_enable")
raise ValueError("Passing through")
if __name__ == "__main__":
with catch_exception() as cm:
staticBox_destroy()
with catch_exception() as cm:
checkbox_disable()
with catch_exception() as cm:
radioButton_enable()

Finding out an exception context

tlndr: how to tell in a function if it's called from an except block (directly/indirectly). python2.7/cpython.
I use python 2.7 and try to provide something similar to py3's __context__ for my custom exception class:
class MyErr(Exception):
def __init__(self, *args):
Exception.__init__(self, *args)
self.context = sys.exc_info()[1]
def __str__(self):
return repr(self.args) + ' from ' + repr(self.context)
This seems to work fine:
try:
1/0
except:
raise MyErr('bang!')
#>__main__.MyErr: ('bang!',) from ZeroDivisionError('integer division or modulo by zero',)
Sometimes I need MyErr to be raised outside of an exception block. This is fine too:
raise MyErr('just so')
#>__main__.MyErr: ('just so',) from None
If, however, there has been a handled exception before this point, it's being incorrectly set as a context of MyErr:
try:
print xxx
except Exception as e:
pass
# ...1000 lines of code....
raise MyErr('look out')
#>__main__.MyErr: ('look out',) from NameError("name 'xxx' is not defined",) <-- BAD
I guess the reason is that sys.exc_info simply returns the "last" and not the "current" exception:
This function returns a tuple of three values that give information about the exception that is currently being handled. <...> Here, “handling an exception” is defined as “executing or having executed an except clause.”
So, my question is: how to tell if the interpreter is executing an except clause (and not has it executed in the past). In other words: is there a way to know in MyErr.__init__ if there is an except up on the stack?
My app is not portable, any Cpython specific hacks are welcome.

This is tested with CPython 2.7.3:
$ python myerr.py
MyErr('bang!',) from ZeroDivisionError('integer division or modulo by zero',)
MyErr('nobang!',)
It works as long as the magic exception is directly created within the scope of an except clause. A little additional code can lift that restriction, though.
import sys
import opcode
SETUP_EXCEPT = opcode.opmap["SETUP_EXCEPT"]
SETUP_FINALLY = opcode.opmap["SETUP_FINALLY"]
END_FINALLY = opcode.opmap["END_FINALLY"]
def try_blocks(co):
"""Generate code positions for try/except/end-of-block."""
stack = []
code = co.co_code
n = len(code)
i = 0
while i < n:
op = ord(code[i])
if op in (SETUP_EXCEPT, SETUP_FINALLY):
stack.append((i, i + ord(code[i+1]) + ord(code[i+2])*256))
elif op == END_FINALLY:
yield stack.pop() + (i,)
i += 3 if op >= opcode.HAVE_ARGUMENT else 1
class MyErr(Exception):
"""Magic exception."""
def __init__(self, *args):
callee = sys._getframe(1)
try:
in_except = any(i[1] <= callee.f_lasti < i[2] for i in try_blocks(callee.f_code))
finally:
callee = None
Exception.__init__(self, *args)
self.cause = sys.exc_info()[1] if in_except else None
def __str__(self):
return "%r from %r" % (self, self.cause) if self.cause else repr(self)
if __name__ == "__main__":
try:
try:
1/0
except:
x = MyErr('bang!')
raise x
except Exception as exc:
print exc
try:
raise MyErr('nobang!')
except Exception as exc:
print exc
finally:
pass
And remember, “Explicit is better than implicit,” so this would be way better if you ask me:
try:
…
except Exception as exc:
raise MyErr("msg", cause=exc)

The following approach might work, although it's a bit long-winded.
Get the code of the current frame from import inspect; inspect.currentframe().f_code
Inspect the bytecode (f_code.co_code), perhaps using dis.dis, to figure out whether the frame is being executed in an except block.
Depending on what you want to do, you might want to go back a frame and see if it wasn't called from an except block.
Ex:
def infoo():
raise MyErr("from foo in except")
try:
nope
except:
infoo()
If none of the frames are in an except block then the sys.exc_info() is outdated.

One solution would be to call sys.exc_clear() after an exception has been handled:
import sys
class MyErr(Exception):
def __init__(self, *args):
Exception.__init__(self, *args)
self.context = sys.exc_info()[1]
def __str__(self):
return repr(self.args) + ' from ' + repr(self.context)
try:
print xxx
except Exception as e:
# exception handled
sys.exc_clear()
raise MyErr('look out')
Gives:
Traceback (most recent call last):
File "test.py", line 18, in <module>
raise MyErr('look out')`
__main__.MyErr: ('look out',) from None
If there is not many places that handle an exception without raising MyErr then it might be more suitable then modifying calls to MyErr providing some constructor argument, or even explicitly handling traceback preservation as in this answer.

I searched through the Python source to see if there was some indicator that was being set when the entering an except block that could be queried by going through the frame sequence from the custom exception's constructor.
I found this fblocktype enum that is stored in a fblockinfo struct :
enum fblocktype { LOOP, EXCEPT, FINALLY_TRY, FINALLY_END };
struct fblockinfo {
enum fblocktype fb_type;
basicblock *fb_block;
};
There is a comment above the fblocktype that describes a frame block :
A frame block is used to handle loops, try/except, and try/finally.
It's called a frame block to distinguish it from a basic block in the
compiler IR.
And then when you go up a bit there is a description of a basic block :
Each basicblock in a compilation unit is linked via b_list in the
reverse order that the block are allocated. b_list points to the next
block, not to be confused with b_next, which is next by control flow.
Also reading some more here about about the Control Flow Graphs :
A control flow graph (often referenced by its acronym, CFG) is a
directed graph that models the flow of a program using basic blocks
that contain the intermediate representation (abbreviated “IR”, and in
this case is Python bytecode) within the blocks. Basic blocks
themselves are a block of IR that has a single entry point but
possibly multiple exit points. The single entry point is the key to
basic blocks; it all has to do with jumps. An entry point is the
target of something that changes control flow (such as a function call
or a jump) while exit points are instructions that would change the
flow of the program (such as jumps and ‘return’ statements). What this
means is that a basic block is a chunk of code that starts at the
entry point and runs to an exit point or the end of the block.
So all this seem to indicate that a frame block in Python's design is treated as a temporary object. It is not directly included in the Control Flow Graph except as part of the encompassing basic block's byte code, so it seems it can not be queried without parsing the frames byte code.
Further, I think the reason in your example the sys.exc_info is showing the exception from the try block is because it stores the last exception of the current basic block, frame blocks are not considered here.
sys.exc_info()
This function returns a tuple of three values that give information
about the exception that is currently being handled. The information
returned is specific both to the current thread and to the current
stack frame. If the current stack frame is not handling an exception,
the information is taken from the calling stack frame, or its caller,
and so on until a stack frame is found that is handling an exception.
Here, “handling an exception” is defined as “executing or having
executed an except clause.” For any stack frame, only information
about the most recently handled exception is accessible.
So when it says stack frame there I think it specifically means basic block and all the "handling an exception" talk means that exceptions in a frame block such as a try/except, for, and etc. bubble up to the basic block above.