Hey Dennis,
After trying yours, I do get followng console message:
Uncaught TypeError: this.onMyMethod is not a function
Strangely underneath where I did call your code I declared my method but this is not found 
. On the whole it looks as follows:
init: function(oEvent, aServiceOrders) {
this._oSmartFilter.attachSearch(function(oEvent) { this.onMyMethod(oEvent).bind(this); });
}
onMyMethod: function(oEvent, aServiceOrders) {
}