Question

Say you have,

foo = 'bar'
d = {'a-key':'a-value'}

And you want

d = {'a-key':'a-value','foo':'bar'}
e = {'foo':foo}

I know you can do,

d['foo'] = foo

#Either of the following for e
e = {'foo':foo}
e = dict(foo=foo)

But, in all these way to add the variable foo to dict, I have had to use the word foo twice; once to indicate the key and once for its value.

It seems wasteful to me to use foo twice. Is there a simpler way, in which you can tell python “Add this variable to the dictionary with its name as the key and its value as the value”?

Answer 1

Actutally using foo twice is remarkably common in python programs. It is used extensively for passing on arguments eg

def f(foo, bar):
    g(foo=foo)

Which is a specialised case of the dictionary manipulations in your question.

I don’t think there is a way of avoiding it without resorting to magic, so I think you’ll have to live with it.