Add consider-ternary-expression extension
diff --git a/ChangeLog b/ChangeLog
index 53c8708..31a5609 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -69,7 +69,11 @@
Closes #4365
-* Added optional extension ``while_used``: Emitted whenever a ``while`` loop is used.
+* Added optional extension ``consider-ternary-expression``: Emitted whenever a variable is assigned in both branches of an if/else block.
+
+ Closes # 4366
+
+* Added optional extension ``while-used``: Emitted whenever a ``while`` loop is used.
Closes # 4367
diff --git a/doc/whatsnew/2.10.rst b/doc/whatsnew/2.10.rst
index 501c915..becc9be 100644
--- a/doc/whatsnew/2.10.rst
+++ b/doc/whatsnew/2.10.rst
@@ -24,7 +24,11 @@
Closes #4365
-* Added optional extension ``while_used``: Emitted whenever a ``while`` loop is used.
+* Added optional extension ``consider-ternary-expression``: Emitted whenever a variable is assigned in both branches of an if/else block.
+
+ Closes # 4366
+
+* Added optional extension ``while-used``: Emitted whenever a ``while`` loop is used.
Closes # 4367
diff --git a/pylint/extensions/consider_ternary_expression.py b/pylint/extensions/consider_ternary_expression.py
new file mode 100644
index 0000000..976cd20
--- /dev/null
+++ b/pylint/extensions/consider_ternary_expression.py
@@ -0,0 +1,53 @@
+"""Check for if / assign blocks that can be rewritten with if-expressions."""
+
+from astroid import nodes
+
+from pylint.checkers import BaseChecker
+from pylint.interfaces import IAstroidChecker
+
+
+class ConsiderTernaryExpressionChecker(BaseChecker):
+
+ __implements__ = (IAstroidChecker,)
+ name = "consider_ternary_expression"
+ msgs = {
+ "W0160": (
+ "Consider rewriting as a ternary expression",
+ "consider-ternary-expression",
+ "Multiple assign statements spread across if/else blocks can be "
+ "rewritten with a single assingment and ternary expression",
+ )
+ }
+
+ def visit_if(self, node: nodes.If) -> None:
+ if isinstance(node.parent, nodes.If):
+ return
+
+ if len(node.body) != 1 or len(node.orelse) != 1:
+ return
+
+ bst = node.body[0]
+ ost = node.orelse[0]
+
+ if not isinstance(bst, nodes.Assign) or not isinstance(ost, nodes.Assign):
+ return
+
+ for (bname, oname) in zip(bst.targets, ost.targets):
+ if not isinstance(bname, nodes.AssignName) or not isinstance(
+ oname, nodes.AssignName
+ ):
+ return
+
+ if bname.name != oname.name:
+ return
+
+ self.add_message("consider-ternary-expression", node=node)
+
+
+def register(linter):
+ """Required method to auto register this checker.
+
+ :param linter: Main interface object for Pylint plugins
+ :type linter: Pylint object
+ """
+ linter.register_checker(ConsiderTernaryExpressionChecker(linter))
diff --git a/tests/functional/ext/consider_ternary_expression.py b/tests/functional/ext/consider_ternary_expression.py
new file mode 100644
index 0000000..5ed5eaa
--- /dev/null
+++ b/tests/functional/ext/consider_ternary_expression.py
@@ -0,0 +1,17 @@
+if f(): # [consider-ternary-expression]
+ x = 4
+else:
+ x = 5
+
+if g():
+ y = 3
+elif h():
+ y = 4
+else:
+ y = 5
+
+def a():
+ if i(): # [consider-ternary-expression]
+ z = 4
+ else:
+ z = 5
diff --git a/tests/functional/ext/consider_ternary_expression.rc b/tests/functional/ext/consider_ternary_expression.rc
new file mode 100644
index 0000000..39b1d79
--- /dev/null
+++ b/tests/functional/ext/consider_ternary_expression.rc
@@ -0,0 +1,10 @@
+[MASTER]
+load-plugins=pylint.extensions.consider_ternary_expression,
+
+[MESSAGES CONTROL]
+disable=
+ invalid-name,
+ undefined-variable,
+ unused-variable,
+ missing-function-docstring,
+ missing-module-docstring,
diff --git a/tests/functional/ext/consider_ternary_expression.txt b/tests/functional/ext/consider_ternary_expression.txt
new file mode 100644
index 0000000..08e51e6
--- /dev/null
+++ b/tests/functional/ext/consider_ternary_expression.txt
@@ -0,0 +1,2 @@
+consider-ternary-expression:1:0::Consider rewriting as a ternary expression
+consider-ternary-expression:14:4:a:Consider rewriting as a ternary expression
