automatic update of variable attributes

[Ron_MacroMaven]

This is a non-trivial problem.

note.1: where I changed the length of a known variable with the attribute statement

and the var-name does not match the case of the master data set

then that var-name is changed.

Since is this is a demo of proof-of-concept

this may not matter.

note.2 be aware of the fragile nature of the cat* functions;

if they return a value larger than $200 then it will truncate your list

solution: add a length=nnnn after the catx function call

note.3 data structure may be only <1% of your code

but it is the first place I turn to when my algorithm fails.

Likewise here: I recommend adding the data structure of A

to the code that creates B; this is my recommended solution and solves all later appending.

DATA B;
if 0 then set A;
*...;

note.4 this solution assumes both data sets are different

and thus have to be copied in order to change the lengths.

hth

Ron Fehd  list processing maven

*note case of name matters in output;
data class1;
     attrib sex length = $2;
set sashelp.class;

data class2;
     attrib name length = $10;
set sashelp.class;

%macro save_attrib(libname=work, memname=,out=);
PROC sql noprint;
         create table &out as
         select name, lowcase(name) as name_lc, type, length
         from dictionary.columns
         where libname eq "%upcase(&libname)"
           and memname eq "%upcase(&memname)"
           and memtype eq "DATA";
         quit;
run;
%mend;
%save_attrib(memname=class1,out=contents1)
%save_attrib(memname=class2,out=contents2)

DATA attributes;
set contents1
    contents2;
run;
PROC sort data = &syslast;
          by name_lc length;
run;
DATA attributes;
     retain max_length 0;
set  &syslast;
by   name_lc;
if first.name_lc then max_length = 0;
max_length = max(max_length,length);
if last.name_lc then output;
run;
PROC sql noprint;
         select catx(' ',name,'length='
         ,case when type eq 'char' then '$'
               else                     ' '
               end
         ,length) into :list separated by ' '
         from &syslast;
         quit;
%put echo &=list;
%macro update_attrib(data=,base=largest);
DATA &DATA;
     attrib &list;
set &data;
PROC append data = &data
            base = &base;
run;
%mend;
%update_attrib(data=class1)
%update_attrib(data=class2)

proc print data = &syslast;

PROC sql; describe table &syslast;
          quit;