MQL5 OnInit, OnTick and OnDeinit: Build a Reliable EA Lifecycle
Technical revision: 1 October 2026 · Educational materialOn this pageOnInit: validate inputs and own your handlesOnTick: postpone incomplete readsA complete logger with no ordersOnDeinit: release and explainWhat a lifecycle example leaves to the next lessonThe event lifecycle determines when an EA allocates resources, reads prices and releases them. A signal rule can be correct while the surrounding program processes stale history or leaks handles. Use a non-trading logger to learn these boundaries before adding orders. OnInit: validate inputs and own your handles Create indicator handles once during initialization. Check for INVALID_HANDLE and return INIT_FAILED if a required resource cannot be…