Consistent empty lines in the README

[etc/vim.git] / README.md

diff --git a/README.md b/README.md
index 9f72a67ab2494a1a2f9c37912427fcb57c201a6c..475954f1461d2473e7a31c1b4dbf8247984b14b3 100644 (file)
--- a/README.md
+++ b/README.md
@@ -268,6 +268,7 @@ if you'd like a trailing comma in this situation and *Black* didn't
 recognize it was safe to do so, put it there manually and *Black* will
 keep it.
 
+
 ### Strings
 
 *Black* prefers double quotes (`"` and `"""`) over single quotes (`'`
@@ -297,6 +298,7 @@ a bit easier than double quotes.  The latter requires use of the Shift
 key.  My recommendation here is to keep using whatever is faster to type
 and let *Black* handle the transformation.
 
+
 ### Line Breaks & Binary Operators
 
 *Black* will break a line before a binary operator when splitting a block
@@ -308,6 +310,7 @@ This behaviour may raise ``W503 line break before binary operator`` warnings in
 style guide enforcement tools like Flake8. Since ``W503`` is not PEP 8 compliant,
 you should tell Flake8 to ignore these warnings.
 
+
 ### Slices
 
 PEP 8 [recommends](https://www.python.org/dev/peps/pep-0008/#whitespace-in-expressions-and-statements)
@@ -321,6 +324,7 @@ This behaviour may raise ``E203 whitespace before ':'`` warnings in style guide
 enforcement tools like Flake8. Since ``E203`` is not PEP 8 compliant, you should
 tell Flake8 to ignore these warnings.
 
+
 ### Parentheses
 
 Some parentheses are optional in the Python grammar.  Any expression can
@@ -340,7 +344,41 @@ interesting cases:
 
 In those cases, parentheses are removed when the entire statement fits
 in one line, or if the inner expression doesn't have any delimiters to
-further split on.  Otherwise, the parentheses are always added.
+further split on.  If there is only a single delimiter and the expression
+starts or ends with a bracket, the parenthesis can also be successfully
+omitted since the existing bracket pair will organize the expression
+neatly anyway.  Otherwise, the parentheses are added.
+
+Please note that *Black* does not add or remove any additional nested
+parentheses that you might want to have for clarity or further
+code organization.  For example those parentheses are not going to be
+removed:
+```py3
+return not (this or that)
+decision = (maybe.this() and values > 0) or (maybe.that() and values < 0)
+```
+
+
+### Call chains
+
+Some popular APIs, like ORMs, use call chaining.  This API style is known
+as a [fluent interface](https://en.wikipedia.org/wiki/Fluent_interface).
+*Black* formats those treating dots that follow a call or an indexing
+operation like a very low priority delimiter.  It's easier to show the
+behavior than to explain it.  Look at the example:
+```py3
+def example(session):
+    result = (
+        session.query(models.Customer.id)
+        .filter(
+            models.Customer.account_id == account_id,
+            models.Customer.email == email_address,
+        )
+        .order_by(models.Customer.id.asc())
+        .all()
+    )
+```
+
 
 ### Typing stub files
 
@@ -472,14 +510,17 @@ to do this.
 
 Use [joslarson.black-vscode](https://marketplace.visualstudio.com/items?itemName=joslarson.black-vscode).
 
+
 ### SublimeText 3
 
 Use [sublack plugin](https://github.com/jgirardet/sublack).
 
+
 ### IPython Notebook Magic
 
 Use [blackcellmagic](https://github.com/csurfer/blackcellmagic).
 
+
 ### Other editors
 
 Atom/Nuclide integration is planned by the author, others will
@@ -589,6 +630,8 @@ More details can be found in [CONTRIBUTING](CONTRIBUTING.md).
 
 ### 18.5a0 (unreleased)
 
+* call chains are now formatted according to the [fluent interfaces](https://en.wikipedia.org/wiki/Fluent_interface) style (#67)
+
 * slices are now formatted according to PEP 8 (#178)
 
 * parentheses are now also managed automatically on the right-hand side
@@ -619,6 +662,9 @@ More details can be found in [CONTRIBUTING](CONTRIBUTING.md).
 * fixed non-deterministic formatting when multiple pairs of removable parentheses
   were used (#183)
 
+* fixed multiline strings being unnecessarily wrapped in optional
+  parentheses in long assignments (#215)
+
 * fixed not splitting long from-imports with only a single name
 
 * fixed Python 3.6+ file discovery by also looking at function calls with