Adafruit_GFX::operator=(const Adafruit_GFX&)' is implicitly deleted

[vogt31337]

Hi,

Problem: I tried using Adafruit_SSD1306 in a sub class to encapsulate it's behaviour. But Adafruit_GFX resists...

void Display::initialize(void) {
    ssd1306 = Adafruit_SSD1306(128, 32, &Wire);
    [..]
}

Versions: Arduino ver. 1.8.8 GFX ver. 1.3.6 SSD1306 ver. 1.2.9

Error:

display.cpp:4:11: error: use of deleted function 'Adafruit_SSD1306& Adafruit_SSD1306::operator=(const Adafruit_SSD1306&)'

   ssd1306 = Adafruit_SSD1306(128, 32, &Wire);
           ^

In file included from display.h:5:0,
                 from display.cpp:1:

Adafruit_SSD1306.h:115:7: note: 'Adafruit_SSD1306& Adafruit_SSD1306::operator=(const Adafruit_SSD1306&)' is implicitly deleted because the default definition would be ill-formed:

 class Adafruit_SSD1306 : public Adafruit_GFX {
       ^

Adafruit_SSD1306.h:115:7: error: use of deleted function 'Adafruit_GFX& Adafruit_GFX::operator=(const Adafruit_GFX&)'

In file included from display.h:4:0,

                 from zamek-display.cpp:1:

Adafruit_GFX.h:13:7: note: 'Adafruit_GFX& Adafruit_GFX::operator=(const Adafruit_GFX&)' is implicitly deleted because the default definition would be ill-formed:

 class Adafruit_GFX : public Print {
       ^

Adafruit_GFX.h:13:7: error: non-static const member 'const int16_t Adafruit_GFX::WIDTH', can't use default assignment operator

Adafruit_GFX.h:13:7: error: non-static const member 'const int16_t Adafruit_GFX::HEIGHT', can't use default assignment operator

Possible solution: Adafruit_GFX.h, line 132: Remove const.

What's happening? As far as I understood this explanation, you can't assign objects which have const fields in their definition. My C++ skill is too low to understand the details, but removeing the const expression solves this compilation.

[BillyDonahue]

It's correct that this object shouldn't be copied around, as it owns resources in a simple raw pointer and implicit way. It's just luck that the const is what's enforcing this for you (partially, as it blocks copy-assignment but not copy-construction). You should probably switch to using a pointer?

ssd1306 = new Adafruit_SSD1306(128, 32, &Wire);

[vogt31337]

Hmm sounds reasonable, I'll try it and if it works I'll close the issue.