C++ difficulties accessing method from a deep inner class [closed] - c++

Question

Closed. This question is opinion-based. It is not currently accepting answers.
Want to improve this question? Update the question so it can be answered with facts and citations by editing this post.
Closed 5 years ago.
Improve this question
I have several classes in my project and some of those classes are the members of other ones. While manipulating the outer class, I would like to access some parameters of its member classes (which could also have their own member classes).
I guess this is not exactly what are "nested classes" in C++, since nested class are being declared within the declaration of the outer class. Then the nested class may not be accessed from the outside of the outer class (just a piece of information for me, to make sure I don't write garbage).
Let’s say I have an AnalogSensor class (handles the behavior of a real analog sensor). This class may have several handlers (one for ADC requests handling, one for filtering incoming data, one for data handling, and the last one for deadzone management).
class LinearSpace {
public:
// Getters & setters
private:
uint16_t min_val; // I'm working with embedded devices
uint16_t max_val; // Those are values used for linear interpolations
// purposes
};
class DataHandler {
public:
// Some useful methods
uint8_t map_raw_data(); // Converts the mapped adc_result (10 bits)
// value into an 8-bit, interpolated value
private:
LinearSpace input_space; // Two values spaces used for interpolation
// purposes
LinearSpace output_space;
};
class AnalogSensor{
public:
// "High-Level" methods like void send_adc_request(void);
// which relies on the internal ADC hander
private :
AdcHandler adc_handler;
DataHandler data_handler;
Deadzone deadzone;
DataFilter data_filter;
};
Each one of those handlers may rely (or not) on other subclasses, like value ranges (minimum value, maximum value) which has its own getters and setters (getmin, getmax, setmin, and setmax).
Here is an example of what I could end with in my project:
AnalogSensor mysensor
|
- dataHandler data_handler
|
- LinearSpace input_space
| |
| - min_val
| |
| - max_val
|
- LinearSpace output_space
|
- min_val
|
- max_val
Well, now let’s say I want to modify the minimum and maximuml value of a given range, directly from the AnalogSensor class. How should I do?
This requirement comes from the necessity to adjust those values for each calibration process (at runtime), as voltages and electronic measurement may vary with time / external conditions such as moisture, etc.
I found many ideas on the Internet:
Declare a class as friend (AnalogSensor is the friend of
AdcHandler and dataFilter, etc...)
Declare as much getters and setters inside AnalogSensor which are dedicated to target one specific range (there will be tens of them and I think it is pretty dirty).
Or using pointers to access the exact valueRange I want to modify (without
breaking encapsulation I hope) directly from AnalogSensor class.
In this particular case, I can do something like this:
mysensor.getDataHandlerPointer()->getInputSpacePointer()->set_min(my_new_value);
How would you do to access those values?

Answer 1

If you have tens of ranges to change and monitor, it may be wise to store them in (an) array(s), and refer to the ranges by index. i.e.:
struct my_s
{
enum RangeSpace { input_space, output_space, N_SPACES };
void setRange(RangeSpace id, int min, int max) { spaces_[id].setMinMax(min, max); }
// etc...
private:
LinearSpace spaces_[N_SPACES];
};
Such indexing will optimize nicely when using constants when calling, as in:
//...
my_s s;
int a = 0, b = 0;
//...
s.setRange(my_s::input_space, a, b);