Writing Portable Macros (1/2)

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set schedule;

totmiles=sum(of miles1-miles20);

proc print;

var flightid totmiles;

run;

However, in the macro CHECK2, the value assigned to VAL is simply the name PGM,

not the value of PGM. The macro processor resolves &&&VAL into &PGM and then

into the SAS statements contained in the macro variable PGM. Thus, the long value is

stored only once.

Writing Portable Macros

Using Portable SAS Language Functions with %SYSFUNC

If your code runs in two different environments, you have essentially doubled the worth

of your development effort. But portable applications require some planning ahead. For

more details about any host-specific feature of SAS, see the SAS documentation for your

host environment.

You can use the %SYSFUNC macro function to access SAS language functions to

perform most host-specific operations, such as opening or deleting a file. For more

information, see “%SYSFUNC and %QSYSFUNC Functions” on page 283.

Using %SYSFUNC to access portable SAS language functions can save you a lot of

macro coding (and is therefore not only portable but also more efficient). The following

table lists some common host-specific tasks and the functions that perform those tasks.

Table 11.1 Portable SAS Language Functions and Their Uses

Task

SAS Language

Function or

Functions

Assign and verify existence of fileref and physical file FILENAME,

FILEREF,

PATHNAME

Open a file FOPEN, MOPEN

Verify existence of a file FEXIST, FILEEXIST

Get information about a file FINFO,

FOPTNAME,

FOPTNUM

Write data to a file FAPPEND, FWRITE

Read from a file FPOINT, FREAD,

FREWIND, FRLEN

Close a file FCLOSE

150 Chapter 11 • Writing Efficient and Portable Macros

Task

SAS Language

Function or

Functions

Delete a file FDELETE

Open a directory DOPEN

Return information about a directory DINFO, DNUM,

DOPTNAME,

DOPTNUM, DREAD

Close a directory DCLOSE

Read a host-specific option GETOPTION

Interact with the File Data Buffer (FDB) FCOL, FGET,

FNOTE, FPOS,

FPUT, FSEP

Assign and verify librefs LIBNAME, LIBREF,

PATHNAME

Get information about executed host environment commands SYSRC

Note: Of course, you can also use other functions, such as ABS, MAX, and

TRANWRD, with %SYSFUNC. A few SAS language functions are not available

with %SYSFUNC. For more information, see “%SYSFUNC and %QSYSFUNC

Functions” on page 283.

Example Using %SYSFUNC

The following program deletes the file identified by the fileref MyFile:

%macro testfile(filrf);

%let

rc=%sysfunc(filename(filrf,physical-filename));

%if &rc = 0 and %sysfunc(fexist(&filrf)) %then

%let rc=%sysfunc(fdelete(&filrf));

%let rc=%sysfunc(filename(filrf));

%mend testfile;

%testfile(myfile)

Using Automatic Variables with Host-Specific Values

Macro Variables by Task

The automatic macro variables are available under all host environments, but the values

are determined by each host. The following table lists the macro variables by task. The

“Type” column tells you if the variable can be changed (Read and Write) or can be

inspected (Read Only).

Writing Portable Macros 151

Table 11.2 Automatic Macro Variables with Host-Specific Results

Task

Automatic Macro

Variable Type

List the name of the current graphics device

on DEVICE=.

SYSDEVIC Read and write

List of the mode of execution (values are

FORE or BACK). Some host environments

allow only one mode, FORE.

SYSENV Read-only

List the name of the currently executing

batch job, user ID, or process. For example,

on UNIX, SYSJOBID is the PID.

SYSJOBID Read-only

List the last return code generated by your

host environment, based on commands

executed using the X statement in open code.

The X command in the SAS windowing

environment, or the %SYSEXEC (or %TSO

or %CMS) macro statements.

The default value is 0.

SYSRC Read and write

List the abbreviation of the host environment

that you are using.

SYSSCP Read-only

List a more detailed abbreviation of the host

environment that you are using.

SYSSCPL Read-only

Retrieve a character string that was passed to

SAS by the SYSPARM= system option.

SYSPARM Read and write

Time zone name based on TIMEZONE

option.

SYSTIMEZONE Read-only

Time zone ID based on TIMEZONE option. SYSTIMEZONEIDENT Read-only

Current time zone offset based on

TIMEZONE option.

SYSTIMEZONEOFFSET Read-only

Examples Using SYSSCP and SYSSCPL

The macro DELFILE uses the value of SYSSCP to determine the platform that is

running SAS and deletes a TMP file. FILEREF is a macro parameter that contains a

filename. Because the filename is host-specific, making it a macro parameter enables the

macro to use whatever filename syntax is necessary for the host environment.

%macro delfile(fileref);

/* Unix */

%if &sysscp=HP 800 or &sysscp=HP 300 %then %do;

X “rm &fileref..TMP”;

%end;

/* DOS-LIKE platforms */

%else %if &sysscp=OS2 or &sysscp=WIN %then %do;

152 Chapter 11 • Writing Efficient and Portable Macros

X “DEL &fileref..TMP”;

%end;

/* CMS */

%else %if &sysscp=CMS %then %do;

X “ERASE &fileref TMP A”;

%end;

%mend delfile;

Here is a call to the macro DELFILE in a PC environment that deletes a file named C:

SASSasuserDoc1.Tmp:

%delfile(c:sasSasuserDoc1)

In this program, note the use of the portable %SYSEXEC statement to carry out the

host-specific operating system commands.

Now, suppose you know your macro application is going to run on some version of

Microsoft Windows. The SYSSCPL automatic macro variable provides information

about the name of the host environment, similar to the SYSSCP automatic macro

variable. However, SYSSCPL provides more information and enables you to further

modify your macro code.

Example Using SYSPARM

Suppose the SYSPARM= system option is set to the name of a city. That means the

SYSPARM automatic variable is set to the name of that city. You can use that value to

subset a data set and generate code specific to that value. Simply by making a small

change to the command that invokes SAS (or to the configuration SAS file), your SAS

job will perform different tasks.

/* Create a data set, based on the value of the */

/* SYSPARM automatic variable. */

/* An example data set name could be MYLIB.BOSTON. */

data mylib.&sysparm;

set mylib.alltowns;

/* Use the SYSPARM SAS language function to */

/* compare the value (city name) */

/* of SYSPARM to a data set variable. */

if town=sysparm();

run;

When this program executes, you end up with a data set that contains data for only the

town that you are interested in. You can change what data set is generated before you

start your SAS job.

Now suppose you want to further use the value of SYSPARM to control what procedures

your job uses. The following macro does just that:

%macro select;

%if %upcase(&sysparm) eq BOSTON %then

%do;

proc report ... more SAS code;

title "Report on &sysparm";

run;

%end;

%if %upcase(&sysparm) eq CHICAGO %then

%do;

proc chart ... more SAS code;

Writing Portable Macros 153

title "Growth Values for &sysparm";

run;

%end;

. /* more macro code */

%mend select;

SYSPARM Details

The value of the SYSPARM automatic macro variable is the same as the value of the

SYSPARM= system option, which is equivalent to the return value of the SAS language

function SYSPARM. The default value is null. Because you can use the SYSPARM=

system option at SAS invocation, you can set the value of the SYSPARM automatic

macro variable before your SAS session begins.

SYSRC Details

The value of the SYSRC automatic macro variable contains the last return code

generated by your host environment. The code returned is based on the following

commands that you execute:

• the X statement in open code

• the X command a windowing environment

• the %SYSEXEC macro statement (as well as the nonportable %TSO and %CMS

macro statements)

Use the SYSRC automatic macro variable to test the success or failure of a host

environment command.

Note: Since it does not generate an error message in the SAS log, the SYSRC automatic

macro variable is not useful under all host environments. For example, under some

host environments, the value of this variable is always 99, regardless of the success

or failure of the host environment command. Check the SAS companion for your

host environment to determine whether the SYSRC automatic macro variable is

useful for your host environment.

Macro Language Elements with System Dependencies

Several macro language elements are host-specific, including the following:

any language element that relies on the sort sequence

Examples of such expressions include %DO, %DO %UNTIL, %DO %WHILE,

%IF-%THEN, and %EVAL.

For example, consider the following program:

%macro testsort(var);

%if &var < a %then %put *** &var is less than a ***;

%else %put *** &var is greater than a ***;

%mend testsort;

%testsort(1)

/* Invoke the macro with the number 1 as the parameter. */

154 Chapter 11 • Writing Efficient and Portable Macros

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Table of Contents for Writing Portable Macros (1/2)

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Writing Portable Macros (1/2)