Is there something similar to list comprehension in dict?

[Steven D'Aprano]

On Fri, 20 Nov 2009 03:08:01 -0800, DreiJane wrote:

> NB: I wondered about about dict(one=1, two=2) - why not d = {one:1,
> two:2} ? 

Because it doesn't work unless you have defined names one and two.

dict(one=1, two=2) uses keyword arguments, namely one and two. This is 
the same standard mechanism by which you call functions with keyword 
arguments:

myfunc(widget=x, width=5, name='fred', flag=True)


The dict literal syntax requires names one and two to already exist, 
otherwise you have to quote them to make them strings:

d = {'one': 1, 'two': 2}

> Since you do not write L=list((1, 2)) either. 

But you certainly can. It would be wasteful, since first it constructs a 
tuple (1, 2), then it creates a list from that tuple.


> These composed
> objects as basic building blocks make Python code so dense and
> beautiful, thus using "{}" means embracing the language's concept.

I don't understand this sentence.



-- 
Steven