mutableString method

MutableCell<String> mutableString({ ValueCell<double> errorValue = const ValueCell.value(0.0), NumberFormat? format, })

Return a cell which evaluates to a string representation of this cell's value.

The returned cell is a mutable computed cell. If the value of the returned cell is set explicitly, a double is parsed from the assigned string value and is assigned to this cell's value.

errorValue is the value to assign to this cell when there is an error parsing a a double from the string.

format is of type NumberFormat and is used to format the string representation of the num value.

Note errorValue is a ValueCell to allow the default value to be chosen dynamically. If a constant is required use the NumValueCellExtension.cell property e.g. 1.0.cell.

Pitfalls:

A binding is not established between errorValue and this cell. This means that this cell will not react to changes in errorValue. Only the value at the time of assigning a value to the returned cell are used.

Implementation

MutableCell<String> mutableString({
  ValueCell<double> errorValue = const ValueCell.value(0.0),
  NumberFormat? format,
}) =>
    MutableComputeCell(
      arguments: {this},
      compute: () => format?.format(value) ?? value.toString(),
      reverseCompute: (value) {
        this.value = format?.tryParse(value)?.toDouble() ??
            double.tryParse(value) ??
            errorValue.value;
      },
    );