Sometines we need to create a huge ABAP expert routine to shave a mammoth into an elephant by bussines requirements.
And we using the FORM statement to split and structurize a ABAP code, but I've found a little hack that making possible to define and implement custom methods inside of transformation class.
Process consist of only two steps:
1. Methods definition in 1st global part.
2. Methods implementation after ENDMETHOD statement used to artificially close expert routine's body
That's it.
And I don't want discuss possible future migration issues on "BW 15.x", just enjoy.