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Chapter 3: Macro Definitions

Chapter 3: Macro Definitions. Chapter 3: Macro Definitions. Objectives. Define and call a simple macro. Defining a Macro. A macro or macro definition enables you to write macro programs. General form of a macro definition: macro-name follows SAS naming conventions.

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Chapter 3: Macro Definitions

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  1. Chapter 3: Macro Definitions

  2. Chapter 3: Macro Definitions

  3. Objectives • Define and call a simple macro.

  4. Defining a Macro • A macro or macro definition enables you to write macro programs. • General form of a macro definition: • macro-name follows SAS naming conventions. • macro-text can include the following: %MACRO macro-name; macro-text %MEND <macro-name>; • any text • SAS statements or steps • macro variable references • macro statements, expressions, or calls • any combination of the above

  5. Macro Compilation • When a macro definition is submitted, the following occur: • Macro language statements, if any, are • checked for syntax errors • compiled. • SAS statements and other text are • not checked for syntax errors • not compiled. • The macro is stored as a SAS catalog entry in the temporary catalog work.sasmacrby default.

  6. Macro Compilation OPTIONS MCOMPILENOTE=ALL|NONE; The MCOMPILENOTE=ALL option issues a note to the SAS log after a macro definition has compiled. General form of the MCOMPILENOTE= option: The default setting is MCOMPILENOTE=NONE.

  7. Macro Compilation options mcompilenote=all; %macro time; %put The current time is %sysfunc (time(),timeampm.).; %mend time; 1 options mcompilenote=all; 2 %macro time; 3 %put The current time is %sysfunc 4 (time(),timeampm.).; 5 %mend time; NOTE: The macro TIME completed compilation without errors. 3 instructions 76 bytes. m103d01 Example: Submit a macro definition. SAS Log

  8. Macro Storage proc catalog cat=work.sasmacr; contents; title "My Temporary Macros"; quit; PROC CATALOG Output My Temporary Macros Contents of Catalog WORK.SASMACR # Name Type Create Date Modified Date Description ---------------------------------------------------------------- 1 TIME MACRO 11JUN2004:15:55:59 11JUN2004:15:55:59 m103d02 Example: Produce a list of compiled macros stored in the default temporary catalog work.sasmacr.

  9. Calling a Macro %macro-name • A macro call • causes the macro to execute • is specified by placing a percent sign before the name of the macro • can be made anywhere in a program (similar to a macro variable reference) • represents a macro trigger • is not a statement (no semicolon required). • General form of a macro call:

  10. Calling a Macro %time 178 %time The current time is 2:49:39 PM. m103d01 Example: Call the TIME macro. SAS Log

  11. 3.01 Poll • Does the macro call below require a semicolon? • %time •  Yes • No

  12. 3.01 Poll – Correct Answer Does the macro call below require a semicolon? %time  Yes  No A macro call is not a statement. A semicolon is not required and can cause problems.

  13. Simple Macro %macro calc; proc means data=orion.order_item &stats; var &vars; run; %mend calc; This macro contains no macro language statements. m103d03 A macro can generate SAS code. Example: Write a macro that generates a PROC MEANS step. Reference macro variables within the macro.

  14. Simple Macro %let stats=min max; %let vars=quantity; %calc m103d03 Example: Call the CALC macro. Precede the call with %LET statements that populate macro variables referenced within the macro.

  15. Program Flow • searches the designated SAS catalog (work.sasmacr by default) for an entry named macro-name.MACRO • executes compiled macro language statements, if any • sends other text to the input stack for word scanning • pauses while the word scanner tokenizes inserted text, and SAS code, if any, compiles and executes • resumes execution of macro language statements after SAS code executes When the macro processor receives %macro-name, it does the following:

  16. Program Flow Example: Submit the %LET statements and call the CALC macro. Compiler Symbol Table Word Scanner Macro Processor work.sasmacr Input Stack %let stats=min max; %let vars=quantity; %calc # Name Type 1 CALC MACRO 2 TIME MACRO ...

  17. Program Flow The macro processor executes the %LET statements and populates the symbol table. Compiler Symbol Table STATS min max VARS quantity Word Scanner Macro Processor Input Stack work.sasmacr %calc # Name Type 1 CALC MACRO 2 TIME MACRO ...

  18. Program Flow • When the macro processor receives %CALC, it locates CALC.MACRO within the work.sasmacrcatalog. Compiler Symbol Table STATS min max VARS quantity Word Scanner Macro Processor %calc Input Stack work.sasmacr # Name Type 1CALC MACRO 2 TIME MACRO ...

  19. Program Flow • The macro processor opens CALC.MACRO. There are no macro language statements to execute. Compiler Symbol Table STATS min max VARS quantity Word Scanner Macro Processor Input Stack CALC.MACRO %macro calc; proc means data=orion.order_item &stats; var &vars; run; %mend calc; ...

  20. Program Flow • The macro processor places the macro text on the input stack. Compiler Symbol Table STATS min max VARS quantity Word Scanner Macro Processor Input Stack CALC.MACRO proc means data=orion.order_item &stats; var &vars; run; %macro calc; proc means data=orion.order_item &stats; var &vars; run; %mend calc; ...

  21. Program Flow • Macro activity pauses while the word scanner tokenizes text and passes it to the compiler. Compiler Symbol Table proc means data=orion.order_item STATS min max VARS quantity Word Scanner Macro Processor Input Stack CALC.MACRO &stats; var &vars; run; %macro calc; proc means data=orion.order_item &stats; var &vars; run; %mend calc; ...

  22. Program Flow Macro variable references are passed to the macro processor. Compiler Symbol Table proc means data=orion.order_item STATS min max VARS quantity Word Scanner Macro Processor &stats Input Stack CALC.MACRO %macro calc; proc means data=orion.order_item &stats; var &vars; run; %mend calc; ; var &vars; run; ...

  23. Program Flow Symbolic substitution is performed. Compiler Symbol Table proc means data=orion.order_item STATS min max VARS quantity Word Scanner Macro Processor &stats Input Stack CALC.MACRO min max; var &vars; run; %macro calc; proc means data=orion.order_item &stats; var &vars; run; %mend calc; ...

  24. Program Flow The word scanner tokenizes the resolved value and passes it to the compiler. Compiler Symbol Table proc means data=orion.order_item min max; STATS min max VARS quantity Word Scanner Macro Processor Input Stack CALC.MACRO var &vars; run; %macro calc; proc means data=orion.order_item &stats; var &vars; run; %mend calc; ...

  25. Program Flow Word scanning continues. Compiler Symbol Table proc means data=orion.order_item min max; var STATS min max VARS quantity Word Scanner Macro Processor Input Stack CALC.MACRO &vars; run; %macro calc; proc means data=orion.order_item &stats; var &vars; run; %mend calc; ...

  26. Program Flow Macro variable references are passed to the macro processor. Compiler Symbol Table proc means data=orion.order_item min max; var STATS min max VARS quantity Word Scanner Macro Processor &vars Input Stack CALC.MACRO ; run; %macro calc; proc means data=orion.order_item &stats; var &vars; run; %mend calc; ...

  27. Program Flow Symbolic substitution is performed. Compiler Symbol Table proc means data=orion.order_item min max; var STATS min max VARS quantity Word Scanner Macro Processor &vars Input Stack CALC.MACRO quantity; run; %macro calc; proc means data=orion.order_item &stats; var &vars; run; %mend calc; ...

  28. Program Flow The word scanner tokenizes the resolved value and passes it to the compiler. Compiler Symbol Table proc means data=orion.order_item min max; var quantity; STATS min max VARS quantity Word Scanner Macro Processor Input Stack CALC.MACRO run; %macro calc; proc means data=orion.order_item &stats; var &vars; run; %mend calc; ...

  29. Program Flow When a step boundary is encountered, SAS executes the compiled step as macro activity remains paused. Macro activity stops when the %MEND statement is encountered. Compiler Symbol Table proc means data=orion.order_item min max; var quantity; STATS min max VARS quantity Word Scanner Macro Processor run; Input Stack CALC.MACRO %macro calc; proc means data=orion.order_item &stats; var &vars; run; %mend calc;

  30. Macro Execution The SAS log reflects execution of the PROC MEANS step. 52 %let stats=min max; 53 %let vars=quantity; 54 %calc NOTE: There were 732 observations read from the data set ORION.ORDER_ITEM. NOTE: PROCEDURE MEANS used (Total process time): real time 0.03 seconds cpu time 0.03 seconds PROC MEANS source code does not appear in the SAS log. m103d03 SAS Log

  31. Macro Execution OPTIONS MPRINT; OPTIONS NOMPRINT; The MPRINT option writes to the SAS log the text that is generated by macro execution. General form of the MPRINT|NOMPRINT option: The default setting is NOMPRINT.

  32. Macro Execution 55 options mprint; 56 %calc MPRINT(CALC): proc means data=orion.order_item min max; MPRINT(CALC): var quantity; MPRINT(CALC): run; NOTE: There were 732 observations read from the data set ORION.ORDER_ITEM. NOTE: PROCEDURE MEANS used (Total process time): real time 0.01 seconds cpu time 0.01 seconds Example: Set the MPRINT option before calling the macro. • Partial SAS Log

  33. Exercise This exercise reinforces the concepts discussed previously.

  34. Chapter 3: Macro Definitions

  35. Objectives • Define and call macros with parameters. • Describe the difference between positional parameters and keyword parameters.

  36. Review %macro calc; proc means data=orion.order_item &stats; var &vars; run; %mend calc; m103d03 Example: Note macro variable references within the CALC macro.

  37. Review %let stats=min max; %let vars=quantity; %calc %let stats=n mean; %let vars=discount; %calc The user must submit three lines each time. How can this be simplified? m103d03 Example: Call the macro twice, each time with different values of the macro variables STATS and VARS.

  38. Macro Parameters %macro calc(stats,vars); proc means data=orion.order_item &stats; var &vars; run; %mend calc; m103d05 Example: Define a macro with a parameter list of macro variables referenced within the macro.

  39. Positional Parameters %macro calc(stats,vars); proc means data=orion.order_item &stats; var &vars; run; %mend calc; %calc(min max,quantity) m103d05 • Positional parameters use a one-to-one correspondence between the following: • parameter names supplied on the macro definition • parameter values supplied on the macro call

  40. Positional Parameters %MACRO macro-name(parameter-1, … parameter-n); macro text %MEND <macro-name>; • General form of a macro definition with positional parameters: • Parameter names are • parenthesized • comma delimited.

  41. Macro Parameters %macro-name(value-1, … value-n) • General form of a macro call with parameters: Parameter values are • parenthesized • comma delimited. Parameter values can be any text, null values, macro variable references, or macro calls.

  42. Local Symbol Tables When a macro with a parameter list is called, the parameters are created in a separate local symboltable. The macro call initializes a local table: %calc(min max, quantity) Local Table Global Table STATS min max VARS quantity SYSDAY Tuesday SYSLAST _NULL_ CITY Dallas AMOUNT 975

  43. Local Symbol Tables • A local symbol table is • created when a macro with a parameter list is called • deleted when the macro finishes execution. • Macro variables in the local table are available only during macro execution and can be referenced only within the macro.

  44. 3.02 Multiple Choice Poll • A %LET statement outside a macro definition creates a macro variable in the • global symbol table • local symbol table

  45. 3.02 Multiple Choice Poll – Correct Answer • A %LET statement outside a macro definition creates a macro variable in the • global symbol table • local symbol table

  46. Positional Parameters %macro count(opts, start, stop); proc freq data=orion.orders; where order_date between "&start"d and "&stop"d; table order_type / &opts; title1 "Orders from &start to &stop"; run; %mend count; options mprint; %count(nocum,01jan2004,31dec2004) %count(,01jul2004,31dec2004) m103d06a Example: Define and call a macro with positional parameters.

  47. Macros with Positional Parametersm103d06a This demonstration illustrates using positional parameters to specify a range of dates and TABLE statement options for the FREQ procedure.

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