SAS include code into data step - sas

Question

I have dynamically create a myfile.sas with following content:
and a = 0
and b = 0
Now I want to include this file into a data step:
data y;
set x;
if 1=1
%include incl("myfile.sas")
then selektion=0;
else selektion=1;
run;
The result should be:
data y;
set x;
if 1=1
and a=0
and b=0
then myvar=0
else myvar=1;
run;
However I get the following error:
ERROR 388-185: Expecting an arithmetic operator.
ERROR 200-322: The symbol is not recognized and will be ignored.
Is this possible to include the file into the if statement?

Answer 1

Indeed, that doesn't work. You can use %include within a data or proc step to add some lines to it but not within an incomplete statement.
Had your myfile.sas looked like this:
if 1=1
and a = 0
and b = 0
you could have written
data y;
set x;
%include "myfile.sas";;
then selektion=0;
else selektion=1;
run;
Couldn't you have these lines in a macro instead of a file?
%macro mymacro;
and a=0
and b=0
%mend;
data y;
set x;
if 1=1
%mymacro
then selektion=0;
else selektion=1;
run;
If that myfile.sas has to stay as is, you could work around it in this rather convoluted (but still generic) way:
filename myfile temp;
data _null_;
file myfile2;
infile 'myfile.sas' eof=end;
input;
if _n_=1 then put '%macro mymacro;';
put _infile_;
return;
end:
put '%mend;';
run;
%include myfile;
data y;
set x;
if 1=1
%mymacro
then selektion=0;
else selektion=1;
run;

Answer 2

The %INCLUDE needs to be at statement boundary. You could put the IF 1=1 into the same file or into another file. Make sure to include semi-colon to end the %INCLUDE command, but don't include a semi-colon in the contents of of the file.
data y;
set x;
%include incl("if1file.sas","myfile.sas") ;
then selektion=0;
else selektion=1;
run;
A better solution might be to put the code into a macro variable (if less than 64K bytes).
%let condition=
and a = 0
and b = 0
;
data y;
set x;
if 1=1 &condition then selektion=0;
else selektion=1;
run;
If it is longer than 64K bytes then define it as a macro instead.
%macro condition;
and a = 0
and b = 0
%mend;
data y;
set x;
if 1=1 %condition then selektion=0;
else selektion=1;
run;

Answer 3

According to SAS documentation:
%INCLUDE Statement
Brings a SAS programming statement, data lines, or both, into a current SAS program.
The injection you are attempting is not a complete statement, so it fails. A more specific description of the action you are describing would be %INLINE. However, there is no such SAS statement.
Let's call a program that outputs code a 'codegener' and the output it produces the 'codegen'
In the context of your use the codegen is specific to a single statement. This highly suggests the codegener should be placing the codegen in a macro variable (for ease of later use) instead of a file.
Suppose the codegener uses data about statement construction:
DATA statements_meta;
length varname $32 operator $10 value $200;
input varname operator value;
datalines;
a = 0
b = 0
run;
and the codegener is a DATA step
DATA _null_;
file "myfile.snippet";
... looping logic over data for statement construction ...
put " and " varname " = 0 "
...
run;
Change the codegener to be more like the following:
DATA _null_;
length snippet $32000;
snippet = "";
... looping logic over data for statement construction ...
snippet = catx (" ", snippet, "and", varname, comparisonOperator, comparisonValue);
... end loop
call symput('snippet', trim(snippet));
stop;
run;
...
DATA ...
if 1=1 &snippet then ... else ...
run;