How do I test for exceptions in if-statements in python?

Question

i want to write a function to report the different results from another function there are some exceptions among these results but I cannot convert them into if statement

example :

if f(x) raise a ValueError, then my function has to return a string 'Value' if f(x) raise a TypeError, then my function has to return a string 'Type

But I don't know how to do this in Python. Can someone help me out.

My Code is like this: -

def reporter(f,x):    

    if f(x) is ValueError():
        return 'Value'
    elif f(x) is E2OddException():
        return  'E2Odd'
    elif f(x) is E2Exception("New Yorker"):
        return 'E2'
    elif f(x) is None:
        return 'no problem'
    else:
        return 'generic'

WHY ARE YOU SHOUTING? ..... Seriously, please don't use all-caps. It's hard to read and makes our (mental) ears hurt. — Macke
– Macke, Commented Jan 25, 2013 at 6:58
I'm so so sorry about that..I'm just getting crazy about that. My homework will due tomorrow actually. — user2010023
– user2010023, Commented Jan 25, 2013 at 7:02

Rohit Jain · Accepted Answer · 2013-01-25 07:06:33Z

18

You have try-except to handle exceptions in Python: -

def reporter(f,x): 
    try:
        if f(x):  
            # f(x) is not None and not throw any exception. Your last case
            return "Generic"
        # f(x) is `None`
        return "No Problem"
    except ValueError:
        return 'Value'
    except TypeError:
        return 'Type'
    except E2OddException:
        return 'E2Odd'

edited Jan 25, 2013 at 7:06

answered Jan 25, 2013 at 6:59

Rohit Jain

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2 Comments

user2010023 Over a year ago

Thanks! But I have not learned about this in my course. So maybe I cannot use it.

Ashwini Chaudhary Over a year ago

@user2010023 try-except is the only way to handle exceptions.

inspectorG4dget · Accepted Answer · 2013-01-25 07:00:22Z

2

def reporter(f,x):    
    try:
        if f(x) is None:
            return 'no problem'
        else:
            return 'generic'
    except ValueError:
        return 'Value'
    except E2OddException:
        return  'E2Odd'
    except E2Exception:
        return 'E2'

answered Jan 25, 2013 at 7:00

inspectorG4dget

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Comments

Alex · Accepted Answer · 2013-01-25 06:59:14Z

0

You put your function call in a try-except construct like

try:
    f(x)
except ValueError as e:
    return "Value"
except E20ddException as e:
    return "E20dd"

The function itself does not return the exception, the exception is caught outside.

answered Jan 25, 2013 at 6:59

Alex

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Comments

Luca · Accepted Answer · 2025-01-29 03:15:50Z

-2

def reporter(f,x):    
    try:
        if f(x) is None:
            return 'no problem'
        else:
            return 'generic'
    except ValueError:
        return 'Value'
    except E2OddException:
        return  'E2Odd'
    except E2Exception:
        return 'E2'

edited Jan 29 at 3:15

Luca

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answered Jan 28 at 6:11

Mafiya _yt

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