*[<Null safety>](https://dart.dev/null-safety)*
PseudoFile.readOnlyStr(ReadFnStr fn)
See #readOnly()
. Wraps the callback, allowing it to return a String instead of a Uint8List,
but otherwise behaves identical to #readOnly()
.
Implementation
PseudoFile.readOnlyStr(ReadFnStr fn)
: _capacity = 0,
assert(fn != null) {
_readFn = _getReadFn(fn);
}