OOT block with varible type of input/output

How to design OOT block similar to add_const_vXX.cc.t in template form ,I want to design a block that find out difference between float input and integer input but because size of both is 4 bytes ,i don’t handle it,so I want to use template form that generate add_const_ff.cc for float and add_const_ii.cc for integer
I really appreciate everybody’s help.