topic Re: refer a macro variable in a macro in SAS Programming

refer a macro variable in a macro

duanzongran — Sat, 08 Feb 2020 09:35:31 GMT

dear all:

i wanna refer a macro variable in a macro like this:

%let a=%nrstr(%do i= 1 %to 3;);
%let b=%nrstr(%end;);
%macro linshi();
&a.;
%put &i.;
&b.;
%mend;
%linshi();

but the log shows :

NOTE: Line generated by the macro variable "A".
1 %do i= 1 %to 3;
-
180

ERROR 180-322: Statement is not valid or it is used out of proper order.

WARNING: Apparent symbolic reference I not resolved.
&i.
NOTE: Line generated by the macro variable "B".
1 %end;
-
180

ERROR 180-322: Statement is not valid or it is used out of proper order.

What should i do to make it work?

Thanks in advance !

Re: refer a macro variable in a macro

FreelanceReinh — Sat, 08 Feb 2020 14:37:12 GMT

Hello @duanzongran,

I think the error messages are due to the (invisible) macro quoting characters which you introduced by (correctly) using the %NRSTR function.

The deeper issue is that you want to create macro program text, then compile and finally execute this macro, but you mix the first two of these three steps. The compilation of the %MACRO, %PUT and %MEND statements must be deferred similarly to that of the %DO-%END statements. Here's how you can achieve this (and use the %UNQUOTE function to remove the macro quoting characters):

%let a=%nrstr(%do i= 1 %to 3;);
%let b=%nrstr(%end;);

%unquote(
  %nrstr(%macro linshi();)
  &a.;
  %nrstr(%put &i.;)
  &b.;
  %nrstr(%mend;)
)

%linshi();

Re: refer a macro variable in a macro

Astounding — Sat, 08 Feb 2020 15:00:56 GMT

Another working approach would be to create the macro variables A and B without quoting functions:

data _null_;
   call symput('A', '%do i=1 %to 3;');
   call symput('B', '%end;');
run;

Then you can use your macro as is.

Re: refer a macro variable in a macro

Tom — Sat, 08 Feb 2020 15:31:47 GMT

Sounds like the old Doctor joke.

The patient says, "Doctor, it hurts when I do this." "Then don't do that!"

If you really need to dynamically generate code it is going to be much easier to dynamically generate SAS code instead of trying to dynamically generate macro code.

What is the actual problem you are trying to solve by creating that Rube Goldberg machine?

Re: refer a macro variable in a macro

Kurt_Bremser — Sat, 08 Feb 2020 16:48:35 GMT

My thoughts, in sequence:

"This is crazy!"
"This is absolutely crazy!"
"Somebody get help, quickly, for this poor person!"

Really, what is the purpose of this?

Re: refer a macro variable in a macro

Astounding — Sat, 08 Feb 2020 18:08:51 GMT

@Kurt_Bremser ,

I have had such thoughts many times about many posts. My tongue has permanent scars from the number and intensity of times I have bitten it. But not in this case.

To me, this is how you learn about macro language. Try things out, see what works and what doesn't. For the things that don't work, try to figure out why. Then re-test your conclusions.

Of course, I can't guarantee the intention here, but I look at this as a learning experience not application development.

Re: refer a macro variable in a macro

Reeza — Sun, 09 Feb 2020 18:32:24 GMT

Agreed with others here, this is a very weird way to generate code. If you're actually using this code in production or to do an analysis I'd highly recommend you state your actual intent and someone can help you move towards a better solution.

If you're doing this for the pleasure of learning about macros, have fun.