In reply to lucaskoelho:
Hi,
If you are still searching for the answer on how to write a macro then see below,
`define SWITCH_PROP(NUM)
property p_signal_NUM; \ @(posedge clk) !switch_NUM |-> enable_``NUM && !mem_read;
endproperty
Now you just need to call the define above i.e. `SWITCH_PROP(0), and so on with other 19 numbers.
Hope that helps !