kennethreitz/dive-into-python3
1
0
Fork 0
mirror of https://github.com/kennethreitz/dive-into-python3.git synced 2026-06-05 15:00:18 +00:00
Code Issues Packages Projects Releases Wiki Activity

explain empty sets

Browse Source
This commit is contained in:
Mark Pilgrim
2009-07-16 09:09:13 -04:00
parent 68c55d65d5
commit 33e6e053ba
2 changed files with 2 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files
porting-code-to-python-3-with-2to3.html
+1 -1
View File
@@ -1260,7 +1260,7 @@ except:
<h3 id=set_literal><code>set()</code> literals (explicit)</h3>
<p>In Python 2, the only way to define a literal set in your code was to call <code>set(a_sequence)</code>. This still works in Python 3, but a clearer way of doing it is to use the new set literal notation: curly braces. (Dictionaries are also defined with curly braces, which makes sense once you think about it, because dictionaries are just sets of key-value pairs.)
<p>In Python 2, the only way to define a literal set in your code was to call <code>set(a_sequence)</code>. This still works in Python 3, but a clearer way of doing it is to use the new set literal notation: curly braces. This works for everything except empty sets, because dictionaries also use curly braces, so <a href=native-datatypes.html#emptyset><code>{}</code> is an empty dictionary, not an empty set</a>.
<blockquote class=note>
<p><span class=u>&#x261E;</span>The <code>2to3</code> script will not fix <code>set()</code> literals by default. To enable this fix, specify <kbd>-f set_literal</kbd> on the command line when you call <code>2to3</code>.