On Wed, Nov 25, 2015 at 3:28 AM, Random832 <random...@fastmail.com> wrote: > On 2015-11-24, Chris Angelico <ros...@gmail.com> wrote: >> On Wed, Nov 25, 2015 at 1:24 AM, Antoon Pardon >><antoon.par...@rece.vub.ac.be> wrote: >>>> Start thinking of it as a constructor call rather than a literal, and >>>> you'll get past most of the confusion. >>> >>> That doesn't change the fact it does look like a literal and not like >>> a constructor. >> >> Neither of them is a literal, even though one of them isn't even >> constructing a list. Tuples may be constant, but they still don't have >> a literal form. > > How do you define "literal form"? I define it as any syntax that > can participate in ast.literal_eval (And I consider [...] to be a > literal form regardless of whether the ... values are literals or > not). I don't think "Start thinking of it as a constructor call > rather than a literal" is helpful, since it just hides one's > confusion about what a literal is.
https://docs.python.org/3/reference/lexical_analysis.html#literals ast.literal_eval can handle a number of things which are not literals, as long as they use nothing but literals combined by a restricted set of operators. For instance, Python has no complex literals, only imaginary ones - but: >>> ast.literal_eval("1+2j") (1+2j) And Python certainly doesn't have "expression literals", yet: >>> ast.literal_eval("[1,1+1,3]") [1, 2, 3] Its support for list display equally doesn't make that into a literal. > The Python documentation itself seems to assume that "literal" > should only be used for things that are a single token, though I > have no idea where this thinking comes from. Probably the grammar. In other words, it's part of the language's very definition. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
