SAS: Break up long string in code - sas

Question

I find it good practice to restrict my code to within 80 characters per line. Since SAS ignores white space, this usually isn't a problem. However, I occasionally need to refer to some string which is excessively long.
For example,
filename infile "B:\This\file\path\is\really\long\but\there\is\nothing\I\can\do\about\it\because\it\is\on\a\shared\network\drive\and\I\am\stuck\with\whatever\organization\or\lack\thereof\exists\for\directory\hierarchies\filename.txt";
I can think of two solutions:
1) Insert a carriage return. This however makes the code look quite messy and may unwittingly introduce invisible characters (i.e \r\n) into the string.
filename infile "B:\This\file\path\is\really\long\but\there\is\nothing\
I\can\do\about\it\because\it\is\on\a\shared\network\drive\and\I\am\stuck\
with\whatever\organization\or\lack\thereof\exists\for\directory\hierarchies\
filename.txt";
2) Use macro variables to break the string into several parts.
%let part1 = B:\This\file\path\is\really\long\but\there\is\nothing\;
%let part2 = I\can\do\about\it\because\it\is\on\a\shared\network\drive\and\I\am\stuck\;
%let part3 = with\whatever\organization\or\lack\thereof\exists\for\directory\hierarchies\;
%let part4 = filename.txt;
filename infile "&part1.&part2.&part3.&part4.";
%let path = %sysfunc(pathname(infile));
%put &path;
Ideally, I would like something which allows me to follow the indentation scheme of the rest of the code.
filename infile "B:\This\file\path\is\really\long\but\there\is\nothing\
I\can\do\about\it\because\it\is\on\a\shared\network\drive\and\I\am\stuck\
with\whatever\organization\or\lack\thereof\exists\for\directory\hierarchies\
filename.txt";
A possible solution, at least within the context of this example, would be to bypass a declaration altogether and prompt the use for the input file. This does not appear easy to implement, however.

Answer 1

For this type of situation where the string needs to be used as one token then splitting it into separate macro variables is the best approach.
%let basedir=b:\Main Folder;
%let project=This project\has\many\parts;
%let fname=filename.txt ;
...
infile "&basedir/&project/&fname" ;
Note that SAS is happy to convert your directory delimiters between Unix (/) and Windows (\) style automatically for you.
You could also take advantage of using a fileref to point to a starting point in your directory tree.
filename basedir "&basedir";
...
infile basedir("&project/&fname");
You could also store the path in a text file or dataset and use that to generate the path into a macro variable.
data _null_;
infile 'parameter_file.txt' ;
input filename :$256. ;
call symputx('filename',filename);
run;
...
infile "&filename" ;
Another variation on using macro variable is to use multiple %LET statements to initialize a single macro variable. That way you can break the long string into multiple tokens.
%let fname=B:\This\file\path\is\really\long\but\there\is\nothing;
%let fname=&fname\I\can\do\about\it\because\it\is\on\a\shared\network\drive\and\I\am\stuck;
%let fname=&fname\with\whatever\organization\or\lack\thereof\exists\for\directory\hierarchies;
%let fname=&fname\filename.txt;
Or you could use a DATA step to set your macro variable instead.
data _null_;
call symputx('fname',catx('\'
,'B:\This\file\path\is\really\long\but\there\is\nothing\I\can'
,'do\about\it\because\it\is\on\a\shared\network\drive\and\I\am\stuck'
,'with\whatever\organization\or\lack\thereof\exists\for\directory'
,'hierarchies\filename.txt'
));
run;

Answer 2

For a situation where you need to put a long string in code such as a dataset label or some type of description consider using %cmpres. The function has limits but is useful to keep one inside 80 columns if they can use it. Here, my CR and other adjacent white spaces are being "compressed" in to a single space character.
%macro get_filename(FILEPATH_FILE, FILE)
/DES=%cmpres("returns a file's name, placed into var FILE, removing the
file path from FILEPATH_FILE.");

Answer 3

If you do this a lot, use %SYSFUNC() and COMPRESS() to make a user-defined macro like this:
%macro c(text);
%sysfunc(compress(&text, ,s))
%mend;
filename infile %c("B:\This\file\path\is\really\long\but\there\is\nothing\I\
can\do\about\it\because\it\is\on\a\shared\network\drive\
and\I\am\stuck\with\whatever\organization\or\lack\thereof\
exists\for\directory\hierarchies\and\he\uses\B\as\a\drive\
OMG\who\does\that\filename.txt");
%put %c("B:\This\file\path\is\really\long\but\there\is\nothing\I\
can\do\about\it\because\it\is\on\a\shared\network\drive\
and\I\am\stuck\with\whatever\organization\or\lack\thereof\
exists\for\directory\hierarchies\and\he\uses\B\as\a\drive\
OMG\who\does\that\filename.txt");
Option "s" in the COMPRESS() function removes all whitespace characters.
SAS posts notes on the log, you can ignore them:
NOTE: The quoted string currently being processed has become more than 262 characters long. You might have unbalanced quotation marks.