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From: Antoon Pardon <antoon.pardon@rece.vub.ac.be>
Newsgroups: comp.lang.python
Subject: Re: What is a function parameter =[] for?
Date: Tue, 24 Nov 2015 17:41:08 +0100
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Xref: csiph.com comp.lang.python:99366

Op 24-11-15 om 16:48 schreef Chris Angelico:
> On Wed, Nov 25, 2015 at 2:46 AM, Antoon Pardon
> <antoon.pardon@rece.vub.ac.be> wrote:
>> What is your point? I say that [] looks like a literal. Because it
>> sure resembles () which is a literal.
>>
>> That [] in fact isn't a literal doesn't contradict it looks like
>> one.
>>
>> That you can come up with more complicated list expressions that
>> are more easily recognizable as not being literals is beside the
>> point because we have generator expressions that look similar to
>> those list comprehensions and those generator expressions don't
>> contradict that () is a literal.
> 
> () is not a literal either.

The byte code sure suggests it is.

Take the following code:

import dis

def f():
  i = 42
  t = ()
  l = []

dis.dis(f)

That produces the following:


  4           0 LOAD_CONST               1 (42)
              3 STORE_FAST               0 (i)

  5           6 LOAD_CONST               2 (())
              9 STORE_FAST               1 (t)

  6          12 BUILD_LIST               0
             15 STORE_FAST               2 (l)
             18 LOAD_CONST               0 (None)
             21 RETURN_VALUE

So on what grounds would you argue that () is not a literal.

-- 
Antoon.