As background, I found this thread I started three years ago, where I was complaining that %SYSFUNC won't pass a null argument to a function with the argument list is empty.
https://communities.sas.com/t5/SAS-Programming/SYSFUNC-and-null-arguments/m-p/412077#M100760
So I'm definitely not an apologist for SAS; I wish %SYSFUNC behaved like you want it to.
But, I do think it's consistent.
In the DATA step, when a function accepts arguments, if you do not pass an argument, it errors:
17 data _null_ ;
18 x=compress() ;
--------
71
ERROR 71-185: The COMPRESS function call does not have enough arguments.
19 run ;
Clearly the compiler sees the above as passing zero arguments, rather than passing a single null argument.
But if you pass a comma, it does not error:
20 data _null_ ;
21 x=compress(,) ;
22 run ;
And the above is interpreted (I believe) as passing two null arguments to compress.
We can see the same with tranwrd passing no arguments:
76 data _null_ ;
77 x=tranwrd() ;
-------
71
ERROR 71-185: The TRANWRD function call does not have enough arguments.
78 run ;
And tranwrd passing three arguments that are null:
79 data _null_ ;
80 x=tranwrd(,,) ;
-
159
ERROR 159-185: Null parameters for TRANWRD are invalid.
81 run ;
Note that above shows the DATA step compiler actually throws a different error message for "not enough arguments" than it does for "null parameters".
In my testing, the DATA step seems consistent. If a function accepts arguments:
- An empty argument list will error rather than pass a null value as the argument.
- If you use a comma in the list it will pass null value(s) as the argument(s)
When you call a DATA step function via %SYSFUNC, the behavior is consistent.
184 %put %sysfunc(compress()) ;
ERROR: The function COMPRESS referenced by the %SYSFUNC or %QSYSFUNC macro function has too few
arguments.
185 %put %sysfunc(compress(,)) ;
186 %put %sysfunc(compress(,,)) ;
187 %put %sysfunc(compress(,,,)) ;
ERROR: The function COMPRESS referenced by the %SYSFUNC or %QSYSFUNC macro function has too many
arguments.
188 %put %sysfunc(tranwrd()) ;
ERROR: The function TRANWRD referenced by the %SYSFUNC or %QSYSFUNC macro function has too few
arguments.
189 %put %sysfunc(tranwrd(,)) ;
ERROR: The function TRANWRD referenced by the %SYSFUNC or %QSYSFUNC macro function has too few
arguments.
190 %put %sysfunc(tranwrd(,,)) ;
191 %put %sysfunc(tranwrd(,,,)) ;
ERROR: The function TRANWRD referenced by the %SYSFUNC or %QSYSFUNC macro function has too many
arguments.
I disagree with your statement "My original test calls all have the right number of arguments. Some arguments are simply NULL STRINGS."
If you code:
%macro test_null_string_handling(str=);
%put >>%sysfunc(STRIP(&str))<< ;
%mend test_null_string_handling;
%test_null_string_handling()
It is true that the local macro variable STR will have a null value, but this does not mean that you pass a null value to STRIP(). The macro processor will resolve &STR to null, and STRIP will have an empty argument list, which is not allowed. Just the same as if you coded:
%macro test_null_string_handling(str=);
%put >>%sysfunc(STRIP())<< ;
%mend test_null_string_handling;
%test_null_string_handling()
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