CODEWITHSUNDEEP
pythonparametersexpressionparameter-passing
George Adams
George Adams

Reputation: 458

Can I use the value of a variable as a parameter name for a function?

There are a number of StackOverflow questions asking about using a variable as a variable (like this and this, but I don't think this is a duplicate of those. I want to know if I can use the value of a variable as a function parameter.

For example, let's say I want to call a function that will populate one of two different MySQL tables:

data = get_data()                 # data = a full name or a phone number
data_type = get_data_type(data)   # data_type = "name" or "phone"
....
column_names_for_tables = {'name': 'fullname', 'phone': 'phonenum'}
column_name = column_names_for_tables[data_type]
# column_name now = "fullname" or "phonenum", depending on the value of #data

new_entry = MakeNewEntry(date=datetime.datetime.now(), id=123, <column_name>=data)

Of course that last line is not valid Python, but my goal is to dynamically generate the function call:

new_entry = MakeNewEntry(date=datetime.datetime.now(), id=123, fullname=data)

or 

new_entry = MakeNewEntry(date=datetime.datetime.now(), id=123, phonenum=data)

That is, I want to use the value of column_name as the name of my parameter.

Can I do that?

(For this example, please assume that MakeNewEntry() is not under my control - it will accept date, id, and a phonenum or fullname parameter, but can't be refactored.)

Upvotes: 3

Views: 105

Answers (1)

Anonymous
Anonymous

Reputation: 12090

You can use the double star operator to pass in arbitrary arguments to a function:

col = 'foo'
val = 'bar'
kwargs = {col: bar}

some_function(**kwargs)

And you can make that shorter by inlining the dictionary like so:

some_function(**{col: var})

You can mix and match the syntax and end up with something like this:

MakeNewEntry(date=datetime.datetime.now(), id=123, **{column_name: data})

Upvotes: 2

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