topic Re: Deleting local macro variable within a macro in SAS Programming

Deleting local macro variable within a macro

Siddhartha — Thu, 13 Aug 2009 17:18:33 GMT

If I want to delete local macro variable within a macro, what is the process?
Can any one explain me with an example.

Regards,
Sidhu

Re: Deleting local macro variable within a macro

deleted_user — Thu, 13 Aug 2009 17:48:07 GMT

I'm not aware that you can delete a LOCAL macro variable. You can delete a global variable with %SYMDEL. Of course, you can always set the local variable to a null value, but you didn't say what your purpose is, so I don't know whether that would help or not.

Re: Deleting local macro variable within a macro

PatrickG — Fri, 14 Aug 2009 17:42:21 GMT

Alas, but you can't. %SYMDEL only works on global macro variables. If you need to create then delete a macro variable from within a macro, make it global by using the %GLOBAL statement, then you can delete it when done.

Re: Deleting local macro variable within a macro

Peter_C — Mon, 17 Aug 2009 16:53:14 GMT

why would you need to delete the local macro variable?
Make the macro siimpler and lose the local mvars as it closes.
There are many ways to eliminate such a problem.

good luck
PeterC

Re: Deleting local macro variable within a macro

Scott_C_Moore — Tue, 20 Aug 2013 15:30:01 GMT

****************Update on 7/2/2015 I was informed by tech support that this works in SAS version 9.3 as a result of a glitch - it does not work in SAS 9.4****************************************

I know this is an old thread but I found it unanswered and then figured out a solution.

%macro _localvaltest ();

/*setting up a local macro variable and putting it into a dataset*/

%let localvar=1;

data new;

set sashelp.shoes;

local=&localvar;

run;

/*creating a set that contains currently defined macro variables*/

data vars;

set sashelp.vmacro;

run;

/*write local vars to the log*/

%put _local_;

%put localvar value is &localvar;

/*executing a null step that deletes local variables from the macro table*/

data _null_;

set vars;

if scope='_LOCALVALTEST' then call execute ('%symdel '||trim(left(name))||';');

run;

/*write local vars to the log after the delete - does not show any and comes back unresolved for second put*/
%put _local_;

%put localvar value is &localvar;

/*creating a new set that shows the local macro variable has been deleted by the previous step*/

data vars2;

set sashelp.vmacro;

run;

%mend;

%_localvaltest;

Message was edited by: Scott Moore; Updated to correct syntax error and add %put statemets.

Re: Deleting local macro variable within a macro

Quentin — Tue, 20 Aug 2013 17:20:02 GMT

Hi Scott,

I don't think that's a solution. I'm getting all kinds of errors, starting with the first comment which is missing a / at the end. So as posted everything except the last data step is commented out.

It would be quite surprising if you could trick %SYMDEL into deleting a local variable.

If you play with this more and it still looks like you have deleted a local macro variable, I woud suggest:

1. ) add %put _local_ ; before and after your deletion, to show the change

2. ) turn on options MPRINT and run the code in batch (so you know you have a clean session)

3. ) post the log from that session (showing both the macro definition and the execution.

Kind Regards,

--Q.

Re: Deleting local macro variable within a macro

Scott_C_Moore — Tue, 20 Aug 2013 17:43:43 GMT

Couldn't figure out how to cut and paste from my SAS editor and ended up typing the reply, which is never a good idea. Fixed the problem and tested it's working properly.

Re: Deleting local macro variable within a macro

data_null__ — Tue, 20 Aug 2013 18:14:40 GMT

If you have SAS/EG use Copy HTML Source to Clipboard then click HTML in "this" editor and past.

Re: Deleting local macro variable within a macro

data_null__ — Tue, 20 Aug 2013 18:18:05 GMT

Do another test and make a global version of the local macro variable you are trying to delete. Which one gets deleted?

Re: Deleting local macro variable within a macro

Scott_C_Moore — Tue, 20 Aug 2013 18:37:20 GMT

If I create a global version of the same variable, the scope in the sashelp.vmacro is global and it no longer meets the condition of if scope= '_LOCALVALTEST' so it does not get deleted. I'll edit the program one more time to %put the value of the macro variable and it will come back as unresolved for the second %put statement showing that the value has been deleted.

My EG install is broken and getting IT to reinstall is such a hassle that I just use the enhanced editor.

Re: Deleting local macro variable within a macro

DennisWilliams — Wed, 16 Mar 2016 15:56:23 GMT

let me know if this work, thnx

*create variable;
%let var = 1;

*display;
%put varibale var has been create and the value is &var;

*further proof;
data view_var_b4;
set sashelp.vmacro;
run;
*create macro;
%macro del_var (del=);
%symdel &del;
%mend del_var;

*run macro;
%del_var (del=var);

*check variable table
data view_var_after;
set sashelp.vmacro;
run;

*further proof;
%put _user_;

Re: Deleting local macro variable within a macro

SPR — Mon, 30 Apr 2018 18:35:35 GMT

What about simply saying;

%let mvar=;