SAS Macro Library - An Easy Way to Increase the
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1. amp dsnin BY amp byvar RUN Yomeanby byvar amp byvar var amp var PROC PRINT data amp dsnin RUN MEND prtmnby1 MACRO meanby dsnin _last_ dsnout byvar var Hif length amp dsnout 0 then let dsnout amp dsnin PROC MEANS data amp dsnin noprint BY amp byvar VAR amp var OUTPUT out amp dsnout RUN Advanced Tutorials 73 MEND meanby Macro definition B nested macro definition MACRO prtmnbyi dsnin _last_ byvar var MACRO meanby dsnin _last_ dsnout byvar var Wit length amp dsnout 0 then let dsnout amp dsnin PROC MEANS data amp dsnin noprint BY amp byvar VAR amp var OUTPUT out amp dsnout RUN MEND meanby PROC SORT data amp dsnin BY amp byvar RUN Ymeanby byvar amp byvar var amp var PROC PRINT data amp dsnin AMEND prtmnby SAS code for invoking macro prtmnby1 Title Correct Title Yprtmnby l byvar group dose time var ci Title Wrong Title Macro resolutions for A PROC SORT DATA _LAST_ BY GROUP DOSE TIME RUN PROC MEANS DATA _LAST_ NOPRINT BY GROUP DOSE TIME VAR CI OUTPUT OUT LAST RUN PROC PRINT DATA _LAST_ RUN The title for the printout is Correct Title Macro resolutions for B They are the same as those for A except that these is no RUN statement after PROC PRINT NESUG 92 Proceedings Advanced Tutorials which causes the title2. Consistent with SAS Tradition NESUG 92 Proceedings Advanced Tutorials SAS traditions such as default data set name should be followed as much as possible For example if no input data set is specified the most recent data set will be used as the input data set if no output data set is specified the output data set will be the same as the input data set Macro Name The macro name should be meaningful and expandable in a structured manner DESIGN The following are some of the general design considerations The Macros Should Be General For example a certain operation can be applied on a series of variables not just one variable and the variable names do not have to be VARI VAR2 VARa Consistent in the Way of Invoking a Macro There are two ways to invoke macros statement style and name style If combining elements of name style and statement style macro invocations in the same call unexpected results may occur There are several reasons to use name style rather than statement style invocation 1 It is easy to identify a name style invocation in SAS code 2 Macros can be invoked anywhere in SAS code by name style invocation 3 Statement style invocation may cause conflict if the macro name and variable are the same The Information Needed for Macro Executing Should Be Passed Through Parameters Coupling and side effects will be minimized because all parameters are local variables The keywo
3. Library Security The write authority to the library should only be granted to one person or account who usually is the library administrator The library project member should have the read authority while the user should only have the execute authority Low Coupling and No Side Effects The information should be passed by parameters for communication between open SAS code and macro and between macro and macro All local variables should be declared local to limit their visibility Consistent with SAS Tradition To be consistent with SAS in handling default data set name the input data set name of a macro should have a default value of LAST_ and the output data set name should be determined by the statement if length amp dsnout O then let dsnout amp dsnin See example 1 of the appendix SOME OTHER ISSUES Well designed test cases are very important to a macro library Macros must be verified code review and testing before being put into the library The functions of a macro should be limited otherwise the long and complicated codes will cause difficulties in verification CONCLUSION To build and maintain a useful SAS macro library is not an easy job but its reward is tremendous A software engineering approach is very helpful during the life time of the library APPENDIX Example 1 Macro definition A nested macro invocation MACRO prtmnbyi dsnin _last_ byvar var PROC SORT data
4. short cut not supported by SAS should not be used Other Standards If staffs are experienced a cleanroom software development approach may be used If so the cleanroom approach is another standard of the project Advanced Tutorials 71 Procedure for Accepting User Provided Macros This procedure describes the steps to accept a user provided macro Some necessary steps would be to complete requirement and design documents recode according to coding standards and pass the verification Code Review Procedure This procedure describes how code should be reviewed Use code walk through and or code inspection techniques The key point regarding standards and procedures is that overall they should make the job easier REQUIREMENTS OF THE LIBRARY The following are some of the library requirements Library Security A library should be protected against unauthorized and erroneous access which may damage or destroy the library Information Hiding For each macro defined in the library only the necessary information for using the macro i e the interface should be provided to the user but not the implementation of the macro Low Coupling Macros should not be coupled with each other or with the macros which a user defines in one s program No Side Effects Macros should have no side effects Neither undesired data set change and deletion nor undesired changes of macro variables value should happen
5. 70 Advanced Tutorials SAS Macro Library An Easy Way to Increase the Productivity and Improve the Quality of SAS Programming Procter amp Gamble Pharmaceuticals Inc INTRODUCTION SAS provide tools to support a SAS macro autocall library which can be accessed by any SAS user who has the access authority The user can simply invoke the macros in the library from one s program without defining them in the program Macros can be shared easily The productivity of SAS programmers can be increased dramatically A SAS macro library can be set up in any computer system which supports SAS autocall facility In the IBM MVS TSO system Partitioned Data Set PDS can be used to support the library while in the IBM CMS system the MACLIB utility can be used to support the library In the VAX VMS system source statement directory or a VMS text library can be used to support the library There are many ways to organize the library centralized decentralized or hybrid No matter what computer system and library organization are used the library must be reliable and the macros must be correct To make a quality product a good process is essential To build and maintain a quality SAS macro library a software engineering approach should be adopted This is because building a library is a group activity and during the life time of the library there will be multiple versions of the macro code and some personnel changes The configurat
6. code file 1 Current release repository 2 Backups and history There should be a policy to handle an abnormal situation For example if fault is discovered in a macro the macro needs to be taken off the library and the user should be informed by e mail immediately also the help library needs to be updated Usually two documents are used to process change 1 The new macro request document filled up by the user to indicate the desire of having a new macro 2 The discrepancy report document filled up by the user to indicate faults of the existing macro in the library During the life time of the library macro code will be updated either because SAS releases its new version or a better design and implementation for a macro is introduced A policy dealing with when the library should be revised and how it should be done is necessary The key point regarding policy is that policy should be useful easy to follow and relevant to the project QUALITY ASSURANCE A quality assurance plan describes the standards and the procedures for the project Some important standards and procedures related to a SAS macro library are Documentation Standards It specifies the format for all documents Design and Coding Standards It specifies some should s and some should not s For example in coding all SAS keyword should be in upper case In design only the semantics which SAS manual tells explicitly should be used
7. for the printout to be Wrong Title Example 2 The JCL code for adding a macro to the library tf EXEC PGM IEBUPDTE PARM NEW HSYSPRINT DD SYSOUT A HSYSUT2 DD DSN PDSname DISP MOD JISYSIN DD ADD NAME membername LIST ALL MACRO macroname macro code MEND macroname ENDUP pe Notice that the member name in JCL and the macro name in SAS macro definition should be the same Example 3 The CMS command MACLIB for creating a macro library adding a member to and deleting a member from the library 1 Creating a library MACLIB GEN libname fn 2 Adding a member to the library MACLIB ADD libname fn 3 Deleting a member from the library MACLIB DEL libname membername libname file name of a macro library file type must be MACLIB fa name of macro definition file file type must be COPY file must contain fixed length 80 character records REFERENCES SAS Language Reference Version 6 First Edition SAS Institute Inc SAS Guide to Macro Processing Version 6 Second Edition SAS Institute Inc System 370 Job Control Language Second Edition Gary DeWard Brown NESUG 92 Proceedings VM SP CMS Command Reference Release 6 IBM Fundamentals of Software Engineering Carlo Ghezzi Concepts of Programming Languages Robert W Sebesta SAS is a registered trademark of SAS Institute Inc TBM is a registered trademark of International Business Machines Corporation Comments and inf
8. ion management plan quality assurance plan and design of the library are the important aspects of the process A configuration management plan defines all policies related to the project It provides the methods for managing configuration items during the life time of the project including the maintenance A quality assurance plan describes the standards and the procedures for the project Design answers the questions addressed in the requirement of the project in technical detail NESUG 92 Proceedings This paper discusses some of the issues of building a SAS macro autocall library CONFIGURATION MANAGEMENT There are two kinds of things that need to be considered configuration items and policies Configuration Items For a SAS macro library there are three types of items that need to be considered 1 All the documents including the requirement document design document user manual configuration management plan some reports ete 2 Source Code files 3 Help library files Organizations and Policies An organization to manage the project needs to be set up The responsibility of each job needs to be defined The process of evaluating and approving or disapproving changes to any project configuration item also needs to be established All the configuration items should be controlled by their corresponding policies The following are some of the issues which should be addressed by the policy governing the source
9. ormation please contact Lu Xu Procter amp Gamble Pharmaceuticals Inc 17 Eaton Ave Norwich NY 13815 Tel 607 335 2992
10. rd parameter passing method should be used which can incorporate default values of parameters easily make the order of the NESUG 92 Proceedings parameter irrelevant and help user to understand the function of the macro The Data Set and Macro Variable Created by the Macro Should Be Named in a Special Way In order to eliminate the side effects the data set and macro variable created by the macro should be named in a special way and let all SAS users who will use the library know this These names will be reserved All the data sets created within the macro are temporary which will be deleted at the end of the execution to keep the memory usage at a minimum Reference Environment and Nested Macro Invocation In the SAS macro system symbolic substitution method which is similar to pass by value parameter passing method is used for macro variable reference Reference environment is dynamically determined based on invoking sequence Macros do not need to be defined in a nested way If a nest reference is needed the only thing to do is to nest the invocation Because of the dynamic characteristic sometime the RUN statement determines the reference environment See example 1 in the appendix for comparing a nested definition and invocation and effect of the RUN statement The general tule is that the RUN statement should always be used for the DATA and PROC steps The following are some of the specific design considerations
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