Print Error Type when I catch it

[Steven D'Aprano]

On Thu, 22 Apr 2010 16:50:30 -0700, Jimbo wrote:

> Hello
> 
> I have a relatively simple question. I want to use a try except in a
> function & when an error occurs I want to print the error type name(eg
> IOError, OSError etc) do you know how I can do this without specifying
> all possible errors, eg having to do this "except (IOError, OSError,
> IndexError, ....):"
> 
> try:
> 
>     ... some code
> 
> except:
>      # Here I want to print type of error that occured print errorType

As a general rule, bare excepts are terrible practice and should be 
avoided.

At most, you should write:


try:
    ...
except Exception:
    ...

which will allow keyboard interrupts to continue to work correctly.

In Python 2.5 or 2.6, you can say:

try:
    ...
except Exception, e:
    print e  # prints the exception object
    print type(e)  # prints the type of exception
    print type(e).__name__  # prints the type's name
    raise  # re-raise the error and get a traceback

In Python 2.6 you can also use

except Exception as e:

and in 3.x you *must* use the "as e" form.


> The reason I want to do this is because one of my complex programs is
> crashing 

Perhaps you should aim to make them less complex? *wink*


> BUT no python error message is comming up in red when I run it,

What do you mean, "crashing"? If you're not getting an exception raised, 
and a printed traceback, how do you know it is crashing?

Do you mean it is dumping core? If so, then a try...except won't save you.


> so I cant figure out what error occured? So I think its time I learnt to
> print out my own errors & their types

The best way to print out errors is:

DO ABSOLUTELY NOTHING.

Python will automatically print out the errors, unless you suppress them 
with a try...except. So stop suppressing them and let Python do what it 
is supposed to do!


-- 
Steven