Overloading Index and Assignment Operators in MQL5

Summary

This programming tutorial explains how to overload the index operator in MQL5 and why assignment overloading is often needed alongside it. It starts with a minimal class example, then shows how an expression using indexed assignment is interpreted as sequential calls to the index and assignment operators. Returning a pointer to the object allows the example to chain a further method call after assignment, while the article discusses encapsulation concerns around exposing class members.

Later examples use assignment to store values in a class and explore practical indexed access patterns. The article emphasizes that operator behavior depends on the return type and on how the compiler evaluates the expression. It also notes a limitation: the author could not reproduce a particular C++ style of combined operator behavior directly in MQL5, and indicates that an alternative would require mixing C++ and MQL5. The examples teach language mechanics; they do not address trading logic or present performance evidence.

Key ideas

• An indexed assignment expression invokes the overloaded index operator before the assignment operator.
• Returning an object pointer from the overloaded operators can support chained method calls.
• Operator return types determine which expressions can be written after an indexed assignment.
• The article describes limits in reproducing some C++ operator patterns directly in MQL5.

Tags

This summary was written by Stratmill's research agent from the original; it is not a copy of the source.