AntiElephant questions

• Derived-to-base conversion and friendship confusion
• Need to reduce this whitespace, but seem to be at a limit at how much I can (GNUPLOT)
• Why do I need to delete resources when using copy-assign operator?
• Why must unused virtual functions be defined?
• Sum function with return type large enough to hold result
• Pointer-to-member confusion
• Understanding how Lambda closure type has deleted default constructor
• Compile time error if brace-closed list is the wrong size for class constructor
• In-class initialisers using = for class templates
• Default move constructor and reference members

AntiElephant answers