Flutter style guide: Prefer naming the argument to a setter 'value' (#8691)

packages/flutter/lib/src/cupertino/slider.dart

@@ -225,10 +225,10 @@ class _RenderCupertinoSlider extends RenderConstrainedBox implements SemanticsAc
 
   int get divisions => _divisions;
   int _divisions;
-  set divisions(int newDivisions) {
-    if (newDivisions == _divisions)
+  set divisions(int value) {
+    if (value == _divisions)
       return;
-    _divisions = newDivisions;
+    _divisions = value;
     markNeedsPaint();
   }
 

packages/flutter/lib/src/material/slider.dart

@@ -316,27 +316,27 @@ class _RenderSlider extends RenderConstrainedBox implements SemanticsActionHandl
 
   int get divisions => _divisions;
   int _divisions;
-  set divisions(int newDivisions) {
-    if (newDivisions == _divisions)
+  set divisions(int value) {
+    if (value == _divisions)
       return;
-    _divisions = newDivisions;
+    _divisions = value;
     markNeedsPaint();
   }
 
   String get label => _label;
   String _label;
-  set label(String newLabel) {
-    if (newLabel == _label)
+  set label(String value) {
+    if (value == _label)
       return;
-    _label = newLabel;
+    _label = value;
     additionalConstraints = _getAdditionalConstraints(_label);
-    if (newLabel != null) {
+    if (value != null) {
       // TODO(abarth): Handle textScaleFactor.
       // https://github.com/flutter/flutter/issues/5938
       _labelPainter
         ..text = new TextSpan(
           style: _textTheme.body1.copyWith(fontSize: 10.0),
-          text: newLabel
+          text: value
         )
         ..layout();
     } else {

packages/flutter/lib/src/material/tab_controller.dart

@@ -148,13 +148,13 @@ class TabController extends ChangeNotifier {
   /// TabBarView has been dragged to the left. Similarly a value between
   /// 0.0 and 1.0 implies that the TabBarView has been dragged to the right.
   double get offset => _animationController.value - _index.toDouble();
-  set offset(double newOffset) {
-    assert(newOffset != null);
-    assert(newOffset >= -1.0 && newOffset <= 1.0);
+  set offset(double value) {
+    assert(value != null);
+    assert(value >= -1.0 && value <= 1.0);
     assert(!indexIsChanging);
-    if (newOffset == offset)
+    if (value == offset)
       return;
-    _animationController.value = newOffset + _index.toDouble();
+    _animationController.value = value + _index.toDouble();
   }
 
   @override

packages/flutter/lib/src/physics/simulation_group.dart

@@ -69,8 +69,8 @@ abstract class SimulationGroup extends Simulation {
   }
 
   @override
-  set tolerance(Tolerance t) {
-    currentSimulation.tolerance = t;
-    super.tolerance = t;
+  set tolerance(Tolerance value) {
+    currentSimulation.tolerance = value;
+    super.tolerance = value;
   }
 }

packages/flutter/lib/src/rendering/custom_layout.dart

@@ -282,13 +282,13 @@ class RenderCustomMultiChildLayoutBox extends RenderBox
   /// The delegate that controls the layout of the children.
   MultiChildLayoutDelegate get delegate => _delegate;
   MultiChildLayoutDelegate _delegate;
-  set delegate (MultiChildLayoutDelegate newDelegate) {
-    assert(newDelegate != null);
-    if (_delegate == newDelegate)
+  set delegate (MultiChildLayoutDelegate value) {
+    assert(value != null);
+    if (_delegate == value)
       return;
-    if (newDelegate.runtimeType != _delegate.runtimeType || newDelegate.shouldRelayout(_delegate))
+    if (value.runtimeType != _delegate.runtimeType || value.shouldRelayout(_delegate))
       markNeedsLayout();
-    _delegate = newDelegate;
+    _delegate = value;
   }
 
   Size _getSize(BoxConstraints constraints) {

packages/flutter/lib/src/rendering/performance_overlay.dart

@@ -77,11 +77,11 @@ class RenderPerformanceOverlay extends RenderBox {
   /// [PerformanceOverlayOption] to enable.
   int get optionsMask => _optionsMask;
   int _optionsMask;
-  set optionsMask(int mask) {
-    assert(mask != null);
-    if (mask == _optionsMask)
+  set optionsMask(int value) {
+    assert(value != null);
+    if (value == _optionsMask)
       return;
-    _optionsMask = mask;
+    _optionsMask = value;
     markNeedsPaint();
   }
 
@@ -90,22 +90,22 @@ class RenderPerformanceOverlay extends RenderBox {
   /// is suitable for capturing an SkPicture trace for further analysis.
   int get rasterizerThreshold => _rasterizerThreshold;
   int _rasterizerThreshold;
-  set rasterizerThreshold (int threshold) {
-    assert(threshold != null);
-    if (threshold == _rasterizerThreshold)
+  set rasterizerThreshold (int value) {
+    assert(value != null);
+    if (value == _rasterizerThreshold)
       return;
-    _rasterizerThreshold = threshold;
+    _rasterizerThreshold = value;
     markNeedsPaint();
   }
 
   /// Whether the raster cache should checkerboard cached entries.
   bool get checkerboardRasterCacheImages => _checkerboardRasterCacheImages;
   bool _checkerboardRasterCacheImages;
-  set checkerboardRasterCacheImages (bool checkerboard) {
-    assert(checkerboard != null);
-    if (checkerboard == _checkerboardRasterCacheImages)
+  set checkerboardRasterCacheImages (bool value) {
+    assert(value != null);
+    if (value == _checkerboardRasterCacheImages)
       return;
-    _checkerboardRasterCacheImages = checkerboard;
+    _checkerboardRasterCacheImages = value;
     markNeedsPaint();
   }
 

packages/flutter/lib/src/rendering/shifted_box.dart

@@ -212,11 +212,11 @@ abstract class RenderAligningShiftedBox extends RenderShiftedBox {
   /// Sets the alignment to a new value, and triggers a layout update.
   ///
   /// The new alignment must not be null or have any null properties.
-  set alignment (FractionalOffset newAlignment) {
-    assert(newAlignment != null && newAlignment.dx != null && newAlignment.dy != null);
-    if (_alignment == newAlignment)
+  set alignment (FractionalOffset value) {
+    assert(value != null && value.dx != null && value.dy != null);
+    if (_alignment == value)
       return;
-    _alignment = newAlignment;
+    _alignment = value;
     markNeedsLayout();
   }
 

packages/flutter/lib/src/rendering/sliver_fixed_extent_list.dart

@@ -163,11 +163,11 @@ class RenderSliverFixedExtentList extends RenderSliverFixedExtentBoxAdaptor {
   @override
   double get itemExtent => _itemExtent;
   double _itemExtent;
-  set itemExtent (double newValue) {
-    assert(newValue != null);
-    if (_itemExtent == newValue)
+  set itemExtent (double value) {
+    assert(value != null);
+    if (_itemExtent == value)
       return;
-    _itemExtent = newValue;
+    _itemExtent = value;
     markNeedsLayout();
   }
 }
@@ -186,11 +186,11 @@ class RenderSliverFill extends RenderSliverFixedExtentBoxAdaptor {
 
   double get viewportFraction => _viewportFraction;
   double _viewportFraction;
-  set viewportFraction (double newValue) {
-    assert(newValue != null);
-    if (_viewportFraction == newValue)
+  set viewportFraction (double value) {
+    assert(value != null);
+    if (_viewportFraction == value)
       return;
-    _viewportFraction = newValue;
+    _viewportFraction = value;
     markNeedsLayout();
   }
 

packages/flutter/lib/src/rendering/sliver_grid.dart

@@ -426,14 +426,14 @@ class RenderSliverGrid extends RenderSliverMultiBoxAdaptor {
   SliverGridDelegate get gridDelegate => _gridDelegate;
   SliverGridDelegate _gridDelegate;
 
-  set gridDelegate(SliverGridDelegate newDelegate) {
-    assert(newDelegate != null);
-    if (_gridDelegate == newDelegate)
+  set gridDelegate(SliverGridDelegate value) {
+    assert(value != null);
+    if (_gridDelegate == value)
       return;
-    if (newDelegate.runtimeType != _gridDelegate.runtimeType ||
-        newDelegate.shouldRelayout(_gridDelegate))
+    if (value.runtimeType != _gridDelegate.runtimeType ||
+        value.shouldRelayout(_gridDelegate))
       markNeedsLayout();
-    _gridDelegate = newDelegate;
+    _gridDelegate = value;
   }
 
   @override

packages/flutter/lib/src/widgets/page_view.dart

@@ -159,11 +159,11 @@ class _PagePosition extends ScrollPosition {
 
   double get viewportFraction => _viewportFraction;
   double _viewportFraction;
-  set viewportFraction(double newValue) {
-    if (_viewportFraction == newValue)
+  set viewportFraction(double value) {
+    if (_viewportFraction == value)
       return;
     final double oldPage = page;
-    _viewportFraction = newValue;
+    _viewportFraction = value;
     if (oldPage != null)
       correctPixels(getPixelsFromPage(oldPage));
   }

packages/flutter/lib/src/widgets/placeholder.dart

@@ -23,11 +23,11 @@ class PlaceholderState extends State<Placeholder> {
   /// Mutating this field will cause this widget to rebuild with the new child.
   Widget get child => _child;
   Widget _child;
-  set child(Widget child) {
-    if (_child == child)
+  set child(Widget value) {
+    if (_child == value)
       return;
     setState(() {
-      _child = child;
+      _child = value;
     });
   }
 

packages/flutter_markdown/lib/src/markdown_raw.dart

@@ -356,9 +356,9 @@ class _Block {
   List<_Block> subBlocks;
 
   bool get open => _open;
-  set open(bool open) {
-    _open = open;
-    if (!open && subBlocks.isNotEmpty)
+  set open(bool value) {
+    _open = value;
+    if (!value && subBlocks.isNotEmpty)
       subBlocks.last.isLast = true;
   }
 

packages/flutter_test/lib/src/binding.dart

@@ -202,8 +202,8 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
   /// the focus change.
   EditableTextState get focusedEditable => _focusedEditable;
   EditableTextState _focusedEditable;
-  set focusedEditable (EditableTextState editable) {
-    _focusedEditable = editable..requestKeyboard();
+  set focusedEditable (EditableTextState value) {
+    _focusedEditable = value..requestKeyboard();
   }
 
   /// Returns the exception most recently caught by the Flutter framework.

packages/flutter_tools/lib/src/devfs.dart

@@ -113,8 +113,8 @@ class DevFSByteContent extends DevFSContent {
 
   List<int> get bytes => _bytes;
 
-  set bytes(List<int> newBytes) {
-    _bytes = newBytes;
+  set bytes(List<int> value) {
+    _bytes = value;
     _isModified = true;
   }
 
@@ -145,14 +145,14 @@ class DevFSStringContent extends DevFSByteContent {
 
   String get string => _string;
 
-  set string(String newString) {
-    _string = newString;
+  set string(String value) {
+    _string = value;
     super.bytes = UTF8.encode(_string);
   }
 
   @override
-  set bytes(List<int> newBytes) {
-    string = UTF8.decode(newBytes);
+  set bytes(List<int> value) {
+    string = UTF8.decode(value);
   }
 }
 

packages/flutter_tools/lib/src/runner/flutter_command.dart

@@ -77,8 +77,8 @@ abstract class FlutterCommand extends Command<Null> {
       help: 'Build a release version of your app${defaultToRelease ? ' (default mode)' : ''}.');
   }
 
-  set defaultBuildMode(BuildMode buildMode) {
-    _defaultBuildMode = buildMode;
+  set defaultBuildMode(BuildMode value) {
+    _defaultBuildMode = value;
   }
 
   BuildMode getBuildMode() {