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<title>[11879] CalendarServer/trunk/HACKING</title>
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<dt>Revision</dt> <dd><a href="http://trac.calendarserver.org//changeset/11879">11879</a></dd>
<dt>Author</dt> <dd>wsanchez@apple.com</dd>
<dt>Date</dt> <dd>2013-11-01 17:21:16 -0700 (Fri, 01 Nov 2013)</dd>
</dl>
<h3>Log Message</h3>
<pre>Update to match current practice.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#CalendarServertrunkHACKING">CalendarServer/trunk/HACKING</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="CalendarServertrunkHACKING"></a>
<div class="modfile"><h4>Modified: CalendarServer/trunk/HACKING (11878 => 11879)</h4>
<pre class="diff"><span>
<span class="info">--- CalendarServer/trunk/HACKING 2013-11-02 00:09:02 UTC (rev 11878)
+++ CalendarServer/trunk/HACKING 2013-11-02 00:21:16 UTC (rev 11879)
</span><span class="lines">@@ -144,10 +144,6 @@
</span><span class="cx">
</span><span class="cx"> PEP-8 items we do not follow:
</span><span class="cx">
</span><del>- * Lines need not be limited to 79 spaces, but longer lines are
- undesirable. If you can easily do so, try to keep lines under 80
- columns.
-
</del><span class="cx"> * PEP-8 recommends using a backslash to break long lines up:
</span><span class="cx">
</span><span class="cx"> ::
</span><span class="lines">@@ -181,14 +177,6 @@
</span><span class="cx">
</span><span class="cx"> Because that's just silly.
</span><span class="cx">
</span><del>- * Lining up assignments is OK, within reason:
-
- ::
-
- cars = 4
- motorbikes = 8
- bicycles = 18
-
</del><span class="cx"> Additions:
</span><span class="cx">
</span><span class="cx"> * Close parentheses and brackets such as ``()``, ``[]`` and ``{}`` at the
</span><span class="lines">@@ -248,9 +236,8 @@
</span><span class="cx">
</span><span class="cx"> process = subprocess.Popen(...)
</span><span class="cx">
</span><del>- This makes code shorter and removes the runtime indirection (which
- can be relevant in tight loops). It also makes it easier to replace
- one implementation with another.
</del><ins>+ This makes code shorter and makes it easier to replace one implementation
+ with another.
</ins><span class="cx">
</span><span class="cx"> * All files should have an ``__all__`` specification. Put them at the
</span><span class="cx"> top of the file, before imports (PEP-8 puts them at the top, but
</span><span class="lines">@@ -259,8 +246,8 @@
</span><span class="cx">
</span><span class="cx"> * It is more important that symbol names are meaningful than it is
</span><span class="cx"> that they be concise. ``x`` is rarely an appropriate name for a
</span><del>- variable. ``transmogrifierStatus`` is more useful to the reader
- than ``trmgStat``; avoid contractions.
</del><ins>+ variable. Avoid contractions: ``transmogrifierStatus`` is more useful
+ to the reader than ``trmgStat``.
</ins><span class="cx">
</span><span class="cx"> * A deferred that will be immediately returned may be called ``d``:
</span><span class="cx">
</span><span class="lines">@@ -271,9 +258,7 @@
</span><span class="cx"> d.addErrback(onError)
</span><span class="cx"> return d
</span><span class="cx">
</span><del>- * We prefer ``inlineCallbacks`` over ``deferredGenerator``.
- ``inlineCallbacks`` are more readable, and we do not support Python
- versions old enough that ``deferredGenerator`` would be necessary.
</del><ins>+ * Do not use ``deferredGenerator``. Use ``inlineCallbacks`` instead.
</ins><span class="cx">
</span><span class="cx"> * That said, avoid using ``inlineCallbacks`` when chaining deferreds
</span><span class="cx"> is straightforward, as they are more expensive. Use
</span><span class="lines">@@ -306,17 +291,29 @@
</span><span class="cx"> Use of underscores is reserved for implied dispatching and the like
</span><span class="cx"> (eg. ``http_FOO()``). See the Twisted Coding Standard for details.
</span><span class="cx">
</span><del>- * Always use a tuple when using ``%``-formatting, even when only one
- value is being provided:
</del><ins>+ * Do not use ``%``-formatting:
</ins><span class="cx">
</span><span class="cx"> ::
</span><span class="cx">
</span><span class="cx"> error = "Unexpected value: %s" % (value,)
</span><span class="cx">
</span><del>- Do not use the non-tuple form:
</del><ins>+ Use PEP-3101 formatting instead:
</ins><span class="cx">
</span><span class="cx"> ::
</span><span class="cx">
</span><ins>+ error = "Unexpected value: {value}".format(value=value)
+
+ * If you must use ``%``-formatting for some reason, always use a tuple as
+ the format argument, even when only one value is being provided:
+
+ ::
+
+ error = "Unexpected value: %s" % (value,)
+
+ Never use the non-tuple form:
+
+ ::
+
</ins><span class="cx"> error = "Unexpected value: %s" % value
</span><span class="cx">
</span><span class="cx"> Which is allowed in Python, but results in a programming error if
</span><span class="lines">@@ -329,8 +326,9 @@
</span><span class="cx"> numbers = (1,2,3,) # No
</span><span class="cx"> numbers = (1,2,3) # Yes
</span><span class="cx">
</span><del>- It's desirable on multiple lines, though, as that makes re-ordering
- items easy, and avoids a diff on the last line when adding another:
</del><ins>+ The trailing comma is desirable on multiple lines, though, as that makes
+ re-ordering items easy, and avoids a diff on the last line when adding
+ another:
</ins><span class="cx">
</span><span class="cx"> ::
</span><span class="cx">
</span><span class="lines">@@ -368,11 +366,11 @@
</span><span class="cx"> ==============
</span><span class="cx">
</span><span class="cx"> * If a callable is going to return a Deferred some of the time, it
</span><del>- should probably return a deferred all of the time. Return
- ``succeed(value)`` instead of ``value`` if necessary. This avoids
- forcing the caller to check as to whether the value is a deferred
- or not (eg. by using ``maybeDeferred()``), which is both annoying
- to code and potentially expensive at runtime.
</del><ins>+ should return a deferred all of the time. Return ``succeed(value)``
+ instead of ``value`` if necessary. This avoids forcing the caller
+ to check as to whether the value is a deferred or not (eg. by using
+ ``maybeDeferred()``), which is both annoying to code and potentially
+ expensive at runtime.
</ins><span class="cx">
</span><span class="cx"> * Be proactive about closing files and file-like objects.
</span><span class="cx">
</span></span></pre>
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