public ExecutableVariableDefinition() {
AbstractExecutableCalculation execCalculation;
if (EnvironmentUtils.isWindows() && ! EnvironmentUtils.isCygwin()) {
execCalculation = new WindowsExecutableCalculation();
} else {
execCalculation = new UnixExecutableCalculation();
}
setCalculation(execCalculation);
setPath(true);
addValidator(new FileValidator());
}