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pythonif-statement
ben0
ben0

Reputation: 23

shortening python "if" statements

I've been constantly coding in Python using this inefficient style

    checkbox = self.request.get(u'checkbox') # get data from a web form
    if checkbox == u'yes':
        someclass.enabled = True
    else:
        someclass.enabled = False

how do I shorten this?

Upvotes: 2

Views: 424

Answers (9)

martineau
martineau

Reputation: 123393

As pointed-out in another answer you could use dispatch table to do different things based on a value. However using a dictionary's get() method rather than \performing a direct lookup would allow you to also easily handle cases where nothing matches. Since the mapping won't be used again it can be temporary and anonymous.

This approach is very generic and can expanded as necessary, but usually requires extra functions to be written. Because of the latter, for very simple cases like your example, one of the other answers would probably require the least effort.

def do_yes(): print 'do_yes'
def do_no(): print 'do_no'
def do_maybe(): print 'do_maybe'
def no_match(): print 'no_match'

{
  u'yes': do_yes,
  u'no': do_no,
  u'maybe': do_maybe,
}.get(self.request.get(u'checkbox'), no_match) ()

Upvotes: -1

Behram Mistree
Behram Mistree

Reputation: 4308

It's a little unclear if you used booleans in your example because they were inherent to your problem or because they were a convenient example. If you want to assign to variables more complicated types than booleans, you may also want to check out Python's ternary operator (if you're using version 2.5 or greater):

someclass.int_val = 1 if checkbox == u'yes' else 2

which translates to

if checkbox == u'yes':
    someclass.int_val = 1
else
    someclass.int_val = 2

For boolean variables, I'd recommend using Yuushi's solution, but for completeness, this is what it would look like:

someclass.enabled = True if checkbox == u'yes' else False

It's about the same amount of typing, but saves some vertical space, which can be useful.

Upvotes: 1

Ali Afshar
Ali Afshar

Reputation: 41633

If you ever need more than a boolean value, you should consider using the dispatch pattern:

targets = {
  'yes': do_yes,
  'no': do_no,
  'maybe': do_maybe,
}

targets[self.request.get(u'tricheckbox')]()

# where do_yes, do_no, and do_maybe are the functions to call for each state.

Upvotes: 0

Neel
Neel

Reputation: 21243

Python eval the statement and return the output to the statement. So you can use the assign variable in right side.

like

variable = eval_statment

so your example will be

someclass.enabled = self.request.get(u'checkbox') == u'yes'

Upvotes: 1

Garee
Garee

Reputation: 1284

As checkbox == u'yes' returns a boolean value you can simply assign this result to the variable directly.

someclass.enabled = (checkbox == u'yes')

Upvotes: 2

Matthew Trevor
Matthew Trevor

Reputation: 14952

You can just set the value to the outcome of the statement:

checkbox = self.request.get(u'checkbox') # get data from a web form
someclass.enabled = checkbox == u'yes'

Upvotes: 2

Yuushi
Yuushi

Reputation: 26040

You can do this without an if statement:

someclass.enabled = (checkbox == u'yes')

Upvotes: 4

Collin
Collin

Reputation: 12267

Perhaps you could split it into a different function:

def getCheckboxValue(name):
    return (self.request.get(name) == u'yes')

Upvotes: 1

John Mee
John Mee

Reputation: 52233

someclass.enabled = self.request.get(u'checkbox') == u'yes'

Upvotes: 10

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