RowRepeater UIElement in Webdynpro ABAP

Question

Hello,
I want to create a RowRepeater UI Elements in Webdynpro ABAP and fill a certain number of rows at runtime. I looked at the standard component wdr_test_events -> Row_Repeater View in which there is a node in the context bound to the 'datasource' property of the RowRepeater Element and the node is filled using the supply function which has the following code.:
data l type if_row_repeater=>element_row_repeater_data.
  data t type if_row_repeater=>elements_row_repeater_data.
  data i type string.
  define st.
    concatenate `[ Row` i `: Element &1 ]` into l-&1.
  end-of-definition.
  l-first_line_visible = abap_true.
  do 55 times.
    i = sy-index.
    condense i.
    l-element_1 = 'ICON_STATUS_OK'.
    st element_2_tv1.
    st element_2_tv2.
    st element_2_tv3.
    st element_2_tv4.
    st element_2_in1.
    st element_3_tv1.
    st element_3_tv2.
    st element_3_tv3.
    concatenate `RowDescription for row ` i into l-row_description.
    insert l into table t.
    l-first_line_visible = abap_false.
  enddo.
  node->bind_table( t ).
It's very hard to understand what this code is doing exactly  like the statement:
concatenate `[ Row` i `: Element &1 ]` into l-&1.
like what is the meaning of l-&1?
Any help would be highly appreciated.
Thanks.

Answer 1

data l type if_row_repeater=>element_row_repeater_data.
this statement declares a structure of type if_row_repeater=>element_row_repeater_data
data t type if_row_repeater=>elements_row_repeater_data.
this creates a tbale of the same type as above.
define st.
concatenate ` Row` i `: Element &1 ` into l-&1.
end-of-definition.
this is a macro definition in abap
it is using &1 to pass the parameters when you call this macro
using st <paramvalue>  this passed paramvalue will replace the placeholder &1 in the macro.
e.g. when you call it using
st element_2_tv1.
the macro will replace this statement like
concatenate ` Row` i `: Element element_2_tv1 ` into l-element_2_tv1.
thanks
sarbjeet singh