From 79f240b79fc15ce4ba291b2344cd509f8522f92c Mon Sep 17 00:00:00 2001
From: Monty Taylor <mordred@inaugust.com>
Date: Tue, 3 Mar 2020 09:40:07 -0600
Subject: [PATCH] Make PrettyTable optional

PrettyTable as a depend can have a tendency to conflict with other
things that want to use it, which is a shame for a general purpose
library like futurist. Make it optional to reduce the transitive
dependency burden for consumers.

Change-Id: Ie976f7f4e544f273fccf0cf579b82b659cbd48d1
---
 futurist/periodics.py                            | 16 +++++++++++++---
 .../prettytable-optional-2c9198a9250427b6.yaml   |  7 +++++++
 requirements.txt                                 |  1 -
 test-requirements.txt                            |  1 +
 4 files changed, 21 insertions(+), 4 deletions(-)
 create mode 100644 releasenotes/notes/prettytable-optional-2c9198a9250427b6.yaml

diff --git a/futurist/periodics.py b/futurist/periodics.py
index 6b8980b..eb04af7 100644
--- a/futurist/periodics.py
+++ b/futurist/periodics.py
@@ -25,7 +25,10 @@ import random
 import threading
 
 from concurrent import futures
-import prettytable
+try:
+    import prettytable
+except ImportError:
+    prettytable = None
 import six
 
 import futurist
@@ -748,10 +751,17 @@ class PeriodicWorker(object):
         cols = list(_DEFAULT_COLS)
         for c in ['Runs in', 'Active', 'Periodicity']:
             cols.remove(c)
-        self._log.debug("Stopped running %s callbacks:\n%s",
-                        len(self._works), self.pformat(columns=cols))
+        self._log.debug(
+            "Stopped running %s callbacks:\n%s",
+            len(self._works),
+            self.pformat(columns=cols) if prettytable
+            else "statistics not available, PrettyTable missing"
+        )
 
     def pformat(self, columns=_DEFAULT_COLS):
+        if prettytable is None:
+            raise ImportError(
+                "PrettyTable is required to use the pformat method")
         # Convert to a list to ensure we maintain the same order when used
         # further in this function (since order will matter)...
         if not isinstance(columns, (list, tuple)):
diff --git a/releasenotes/notes/prettytable-optional-2c9198a9250427b6.yaml b/releasenotes/notes/prettytable-optional-2c9198a9250427b6.yaml
new file mode 100644
index 0000000..6b50ffc
--- /dev/null
+++ b/releasenotes/notes/prettytable-optional-2c9198a9250427b6.yaml
@@ -0,0 +1,7 @@
+---
+upgrade:
+  - |
+    The ``PrettyTable`` dependency has been made optional, as it
+    is only used in the `Periodics.pformat` method. If the use
+    of that method is important, users should depend on
+    ``PrettyTable`` directly.
diff --git a/requirements.txt b/requirements.txt
index 9387b04..a072ac0 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,4 +4,3 @@
 
 pbr!=2.1.0,>=2.0.0 # Apache-2.0
 six>=1.10.0 # MIT
-PrettyTable<0.8,>=0.7.1 # BSD
diff --git a/test-requirements.txt b/test-requirements.txt
index 8e848c3..59345ba 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -14,3 +14,4 @@ oslotest>=3.2.0 # Apache-2.0
 stestr>=2.0.0 # Apache-2.0
 testscenarios>=0.4 # Apache-2.0/BSD
 testtools>=2.2.0 # MIT
+PrettyTable<0.8,>=0.7.1 # BSD