topic Re: Macros in SAS Programming

Macros

jaiganesh — Tue, 29 Jan 2019 15:21:07 GMT

Hello,

Can Anybody please clarify below question:

"Can a macro create within another macro? If so, how would SAS know where the current macro ended and the new one began? "

Regards,

Jaiganesh

Re: Macros

Kurt_Bremser — Tue, 29 Jan 2019 15:51:11 GMT

Maxim 4: Try It.

Run this code and look at the log:

%macro inner;
%put inner;
%mend;
%put end of outer;
%mend;

%outer

%inner

Re: Macros

Astounding — Tue, 29 Jan 2019 15:54:01 GMT

As @Kurt_Bremser showed, it can be done.

However, good programmers consider that bad practice.

The easiest way to follow this type of code is to add to your %MEND statements, naming the macro being ended:

%mend inner;

%mend outer;

It's not a requirement, it just is easier to follow.

Re: Macros

Kurt_Bremser — Tue, 29 Jan 2019 16:01:59 GMT

An addendum: all macros are always defined in the global symbol table, so nesting macro definitions only causes confusion when reading the code, but serves no other purpose. DON'T DO IT.

Re: Macros

Reeza — Tue, 29 Jan 2019 16:19:10 GMT

You can, but you should never do this. It's really bad practice, and I've never come across such a use case in 15+ years. It can be done, but there are usually better ways.

%macro embeddedexample;

proc print data=sashelp.class (obs=2);
run;

%macro test;

proc print data=sashelp.cars (obs=5);
run;

%mend test;

%mend embeddedexample;


%embeddedexample;

%test;

@jaiganesh wrote:

Hello,

Can Anybody please clarify below question:

"Can a macro create within another macro? If so, how would SAS know where the current macro ended and the new one began? "

Regards,

Jaiganesh

Re: Macros

Tom — Tue, 29 Jan 2019 16:22:11 GMT

Are you asking about actual macros or perhaps you mean macro variables (aka symbols) instead?

To let the macro processor know where the name of the macro variable being referenced ends use a period.

So this code is looking for a macro variable named XXS.

%let xx=dataset;
%let n=32;
%put There are &n &xxs.;

But this code is looking for a macro variable named XX and appending the letter s and a period to the result.

%put There are &n &xx.s.;

Re: Macros

jaiganesh — Tue, 29 Jan 2019 21:40:44 GMT

Thanks for suggestions. I would keep this in mind.