CODEWITHSUNDEEP
python
ILostMySpoon
ILostMySpoon

Reputation: 2409

Try/Except block declaring multiple values

I am trying to write a try/except block that declares two variables that retrieve their values via ConfigParser. The issue I am running into is that it is possible that one or both the values being declared may not be present under a particular section and should be set to None in such a case. I am aware that I can simply add the values under to every config file, however, not all of the configs are consistent in section names which turns into a very tedious task.

Is there a better way to achieve the following try/except block without breaking them up into two separate ones?

try:
    ports = getCfgStr(sectName, 'ports')
    terminal = getCfgStr(sectName, 'terminals')
except KeyError:
    # Need to set ports or terminal to None depending on which raised the KeyError

My workaround solution:

try:
    ports = getCfgStr(sectName, 'ports')
except KeyError:
    ports = None

try:
    terminals = getCfgStr(sectName, 'terminals')
except KeyError:
    terminals = None

Upvotes: 3

Views: 2323

Answers (4)

Leistungsabfall
Leistungsabfall

Reputation: 6488

Interesting question!

How about this:

def lookup(param):
    try:
        return getCfgStr(sectName, param)
    except KeyError:
        return None

ports = lookup('ports')
terminal = lookup('terminals')

Upvotes: 4

shuttle87
shuttle87

Reputation: 15934

Maybe just make a function:

def get_or_default(name, default):
    try:
        result = getCfgStr(sectName, name)
        return result
    except KeyError:
        return default

Call like this:

 ports = get_or_default('ports', None)

However a better approach if you are using ConfigParser would be to alter the getCfgStr function to use the libraries way of doing this: https://docs.python.org/3.4/library/configparser.html#fallback-values

Upvotes: 0

Fran Lupión
Fran Lupión

Reputation: 134

Instead of using the anti-pattern of coding by exception, you could explicitly check if the option is present:

RawConfigParser.has_option(section, option)

If the given section exists, and contains the given option, return True; otherwise return False.

Upvotes: 0

Ihor Pomaranskyy
Ihor Pomaranskyy

Reputation: 5641

The best solution is to make your getCfgStr function able to accept default values, which it will return if there is no such option in section. So your code will be like this:

ports = getCfgStr(sectName, 'ports', None)
terminal = getCfgStr(sectName, 'terminals', None)

If you have to use exceptions, your solution is OK.

Upvotes: 3

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