Tag: SAS

SAS allows the programmer to declare the scope of macro variables using %LOCAL or %GLOBAL, but the macros themselves are always created in the global scope.

Say you have a macro that in another language, say Python, would be considered a function. Within the macro you want a sub-macro (i.e., sub-function) to be used only within the outer macro.

%macro outer;
%put NOTE: outer;

/* This "sub-macro" is defined within the outer macro and is
   intended only for use within the outer macro. */
 %macro inner(foo);
 %put NOTE: inner &foo;
 %mend;

%inner(1);
%inner(2);
%mend;

%outer;

/* If the "sub-macro" has a local scope, the next step would fail */
%inner(3);

/* However, it succeeds */

This can lead to conflicts if the macro %inner is defined somewhere else in the same session. One way of dealing with this is to be careful to give the inner macro a unique name like __outer_inner where the underscores in the prefix suggest a local scope, and adding outer to the macro name indicates the macro is to be used only in the outer macro.

Another option is to use the %sysmacdelete to delete the inner macro:

%macro outer;
%put NOTE: outer;

 %macro inner(foo);
 %put NOTE: inner &foo;
 %mend;

%inner(1);
%inner(2);
/* Delete the inner macro */
%SYSMACDELETE inner;
%mend;

%outer;

/* This fails because of SYSMACDELETE */
%inner(3);

Tested with SAS 9.4M3 on Windows 7.

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Regular expressions are essential for sophisticated text processing, and it is generally easy to transfer knowledge of Perl regular expressions to the SAS functions prxparse, prxmatch, prxposn, etc. However, use caution with the end of line character …

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