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I have searched for other posts, as I felt this is a rather common problem, but all other Python exception questions I have found didn't reflect my problem.

I will try to be as specific here as I can, so I will give a direct example. And pleeeeease do not post any workarounds for this specific problem. I am not specifically interested how you can send an email much nicer with xyz. I want to know how you generally deal with dependent, error prone statements.

My question is, how to handle exceptions nicely, ones that depend on one another, meaning: Only if the first step was successful, try the next, and so on. One more criteria is: All exceptions have to be caught, this code has to be robust.

For your consideration, an example:

try:
    server = smtplib.SMTP(host) #can throw an exception
except smtplib.socket.gaierror:
    #actually it can throw a lot more, this is just an example
    pass
else: #only if no exception was thrown we may continue
    try:
        server.login(username, password)
    except SMTPAuthenticationError:
        pass # do some stuff here
    finally:
        #we can only run this when the first try...except was successful
        #else this throws an exception itself!
        server.quit() 
    else:
        try:
            # this is already the 3rd nested try...except
            # for such a simple procedure! horrible
            server.sendmail(addr, [to], msg.as_string())
            return True
        except Exception:
            return False
        finally:
            server.quit()

return False
           

This looks extremely unpythonic to me, and the error handling code is triple the real business code, but on the other hand how can I handle several statements that are dependent on one another, meaning statement1 is prerequisite for statement2 and so on?

I am also interested in proper resource cleanup, even Python can manage that for itself.

Thanks, Tom

I have searched for other posts, as I felt this is a rather common problem, but all other Python exception questions I have found didn't reflect my problem.

I will try to be as specific here as I can, so I will give a direct example. And pleeeeease do not post any workarounds for this specific problem. I am not specifically interested how you can send an email much nicer with xyz. I want to know how you generally deal with dependent, error prone statements.

My question is, how to handle exceptions nicely, ones that depend on one another, meaning: Only if the first step was successful, try the next, and so on. One more criterion is: All exceptions have to be caught, this code has to be robust.

For your consideration, an example:

try:
    server = smtplib.SMTP(host) #can throw an exception
except smtplib.socket.gaierror:
    #actually it can throw a lot more, this is just an example
    pass
else: #only if no exception was thrown we may continue
    try:
        server.login(username, password)
    except SMTPAuthenticationError:
        pass # do some stuff here
    finally:
        #we can only run this when the first try...except was successful
        #else this throws an exception itself!
        server.quit() 
    else:
        try:
            # this is already the 3rd nested try...except
            # for such a simple procedure! horrible
            server.sendmail(addr, [to], msg.as_string())
            return True
        except Exception:
            return False
        finally:
            server.quit()

return False
           

This looks extremely unpythonic to me, and the error handling code is triple the real business code, but on the other hand how can I handle several statements that are dependent on one another, meaning statement1 is prerequisite for statement2 and so on?

I am also interested in proper resource cleanup, even Python can manage that for itself.

Thanks, Tom

I have searched for other posts, as I felt this is a rather common problem, but all other Python exception questions I have found didn't reflect my problem.

I will try to be as specific here as I can, so I will give a direct example. And pleeeeease do not post any workarounds for this specific problem. I am not specifically interested how you can send an email much nicer with xyz. I want to know how you generally deal with dependent, error prone statements.

My question is, how to handle exceptions nicely, ones that depend on one another, meaning: Only if the first step was successful, try the next, and so on. One more criterion is: All exceptions have to be caught, this code has to be robust.

For your consideration, an example:

try:
    server = smtplib.SMTP(host) #can throw an exception
except smtplib.socket.gaierror:
    #actually it can throw a lot more, this is just an example
    pass
else: #only if no exception was thrown we may continue
    try:
        server.login(username, password)
    except SMTPAuthenticationError:
        pass # do some stuff here
    finally:
        #we can only run this when the first try...except was successful
        #else this throws an exception itself!
        server.quit() 
    else:
        try:
            # this is already the 3rd nested try...except
            # for such a simple procedure! horrible
            server.sendmail(addr, [to], msg.as_string())
            return True
        except Exception:
            return False
        finally:
            server.quit()

return False
           

This looks extremely unpythonic to me, and the error handling code is triple the real business code, but on the other hand how can I handle several statements that are dependent on one another, meaning statement1 is prerequisite for statement2 and so on?

I am also interested in proper resource cleanup, even Python can manage that for itself.

Thanks, Tom

I have searched for other posts, as I felt this is a rather common problem, but all other Python exception questions I have found didn't reflect my problem.

I will try to be as specific here as I can, so I will give a direct example. And pleeeeease do not post any workarounds for this specific problem. I am not specifically interested how you can send an email much nicer with xyz. I want to know how you generally deal with dependent, error prone statements.

My question is, how to handle exceptions nicely, ones that depend on one another, meaning: Only if the first step was successful, try the next, and so on. One more criteria is: All exceptions have to be caught, this code has to be robust.

For your consideration, an example:

try:
    server = smtplib.SMTP(host) #can throw an exception
except smtplib.socket.gaierror:
    #actually it can throw a lot more, this is just an example
    pass
else: #only if no exception was thrown we may continue
    try:
        server.login(username, password)
    except SMTPAuthenticationError:
        pass # do some stuff here
    finally:
        #we can only run this when the first try...except was successful
        #else this throws an exception itself!
        server.quit() 
    else:
        try:
            # this is already the 3rd nested try...except
            # for such a simple procedure! horrible
            server.sendmail(addr, [to], msg.as_string())
            return True
        except Exception:
            return False
        finally:
            server.quit()

return False
           

This looks extremely unpythonic to me, and the error handling code is triple the real business code, but on the other hand how can I handle several statements that are dependent on one another, meaning statement1 is prerequisite for statement2 and so on?

I am also interested in proper resource cleanup, even Python can manage that for itself.

Thanks, Tom

I have searched for other posts, as I felt this is a rather common problem, but all other Python exception questions I have found didn't reflect my problem.

I will try to be as specific here as I can, so I will give a direct example. And pleeeeease do not post any workarounds for this specific problem. I am not specifically interested how you can send an email much nicer with xyz. I want to know how you generally deal with dependent, error prone statements.

My question is, how to handle exceptions nicely, ones that depend on one another, meaning: Only if the first step was successful, try the next, and so on. One more criteria is: All exceptions have to be caught, this code has to be robust.

For your consideration, an example:

try:
    server = smtplib.SMTP(host) #can throw an exception
except smtplib.socket.gaierror:
    #actually it can throw a lot more, this is just an example
    pass
else: #only if no exception was thrown we may continue
    try:
        server.login(username, password)
    except SMTPAuthenticationError:
        pass # do some stuff here
    finally:
        #we can only run this when the first try...except was successful
        #else this throws an exception itself!
        server.quit() 
    else:
        try:
            # this is already the 3rd nested try...except
            # for such a simple procedure! horrible
            server.sendmail(addr, [to], msg.as_string())
            return True
        except Exception:
            return False
        finally:
            server.quit()

return False
           

This looks extremely unpythonic to me, and the error handling code is triple the real business code, but on the other hand how can I handle several statements that are dependent on one another, meaning statement1 is prerequisite for statement2 and so on?

I am also interested in proper resource cleanup, even Python can manage that for itself.

Thanks, Tom

I have searched for other posts, as I felt this is a rather common problem, but all other Python exception questions I have found didn't reflect my problem.

I will try to be as specific here as I can, so I will give a direct example. And pleeeeease do not post any workarounds for this specific problem. I am not specifically interested how you can send an email much nicer with xyz. I want to know how you generally deal with dependent, error prone statements.

My question is, how to handle exceptions nicely, ones that depend on one another, meaning: Only if the first step was successful, try the next, and so on. One more criterion is: All exceptions have to be caught, this code has to be robust.

For your consideration, an example:

try:
    server = smtplib.SMTP(host) #can throw an exception
except smtplib.socket.gaierror:
    #actually it can throw a lot more, this is just an example
    pass
else: #only if no exception was thrown we may continue
    try:
        server.login(username, password)
    except SMTPAuthenticationError:
        pass # do some stuff here
    finally:
        #we can only run this when the first try...except was successful
        #else this throws an exception itself!
        server.quit() 
    else:
        try:
            # this is already the 3rd nested try...except
            # for such a simple procedure! horrible
            server.sendmail(addr, [to], msg.as_string())
            return True
        except Exception:
            return False
        finally:
            server.quit()

return False
           

This looks extremely unpythonic to me, and the error handling code is triple the real business code, but on the other hand how can I handle several statements that are dependent on one another, meaning statement1 is prerequisite for statement2 and so on?

I am also interested in proper resource cleanup, even Python can manage that for itself.

Thanks, Tom