Do you fell "Trailing SL or TP" should be an official function from MetaTrader?

 

It is the case already. If you use the CExpert object from standard library, there are trailing stop management functions.

https://www.mql5.com/en/docs/standardlibrary/expertclasses/expertbaseclasses/cexpert

Documentation on MQL5: Standard Library / Trading Strategy Classes / Base classes for Expert Advisors / CExpert
Documentation on MQL5: Standard Library / Trading Strategy Classes / Base classes for Expert Advisors / CExpert
  • www.mql5.com
Standard Library / Trading Strategy Classes / Base classes for Expert Advisors / CExpert - Reference on algorithmic/automated trading language for MetaTrader 5
 
Trailing stop is already available from UI both for MT4 and MT5.
Trailing Stop - Trading - MetaTrader 4 Help
Trailing Stop - Trading - MetaTrader 4 Help
  • www.metatrader4.com
Stop Loss is intended for reducing of losses where the symbol price moves in an unprofitable direction. If the position becomes profitable, Stop...
 
Stanislav Korotky:
Trailing stop is already available from UI both for MT4 and MT5.

sorry the question is about EA coding, using trailing function.


not manual by hand

 
Rizal Dwi Satria:

sorry the question is about EA coding, using trailing function.

not manual by hand

That was no specified in the question. While coding you are free to implement any trailing you like (using constant distance, zigzag, important levels, parabolic SAR or other algorithm). This is why it will not most likely be ever available as a built-in function. I'd say that trailing is already supported for a coder. Your requirement is not clear.