Flutter.io (dart) - 如何创建左填充覆盖？

Question

在 Flutter 中，容器具有填充：

padding: const EdgeInsets.only(
  left: MyMeasurements.globalLeftPadding,
  right: 20.0,
),

我希望能够覆盖“左”。

如果这样做，我会收到运行时错误：

class MySectionHeader extends StatelessWidget {
    final double left;

MySectionHeader({
  this.left,
});

// down to the widget body
padding: const EdgeInsets.only(
  left: left ?? MyMeasurements.globalLeftPadding,
  right: 20.0,
),

// and in the container that has the override...
new MySectionHeader(
  left: 12.0,
),

这也会出现运行时错误：

padding: const EdgeInsets.only(
  left: left ?? 14.0,
  right: 20.0,
),

// and in the container that has the override...
new MySectionHeader(
  left: 12.0,
),

建议？

Answer 1

您不能同时使用const 构造函数和动态内容。 改为new EdgeInsets.only(