Questions about list-creation

[Terry Reedy]

Manuel Graune wrote:
> in (most) python documentation the syntax "list()"
> and "[]" is treated as being more or less the same
> thing.

Untrue. List() and [] happen to both evaluate to the same thing, an 
empty list. But there is no reason to expect list(<sometext>) and 
[<sometext>] to always evaluate to the same thing. The docs for list() 
calls and [] displays and comprehensions are quite different.

In particular, they clearly say that [x] interprets x as an item and 
creates a list with one item, x, while list(x) interprets x as an 
iterable, and creates a list with multiple items, the items of x. So. in 
particular, list([]) != [[]].

> For example "help([])" and "help(list())" point
> to the same documentation.

This has nothing to do with list(text) and [text]. [] evaluates to an 
instance that has no doc string, so help backs up to its class. Compare

 >>> help(1)
Help on int object:
...

The alternative to to print nothing, which would not be very helpful.

Try

 >>> help()
...
help> topics

and you will see that there is a topic LISTLITERALS, though not one for 
comprehensions or sets or even generators. The list of topics seems not 
to have been kept up to date.

Terry Jan Reedy