flatter.io（dart）-如何创建左填充覆盖？

在颤振中，容器具有填充物：

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

我希望能够覆盖“左”

如果执行此操作，则会出现运行时错误：

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,
),

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

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

这还将获得一个运行时错误：

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,
),

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？

您不能同时使用

const

构造函数和动态内容。 只执行新边设置（）