Macro Variable Existence Check with Scope

This macro, named `mvartest`, extends the functionality of SAS^©'s `%SYMEXIST()` macro function. It allows determining if a macro variable exists, not only by its name but also within a specific macro scope. The input parameters are `mvar` (the name of the macro variable to check) and `scope` (the optional macro scope in which to perform the search). The macro dynamically constructs a WHERE clause to query the `sashelp.vmacro` system view. It returns `1` if the macro variable is found within the specified scope (or globally if no scope is provided), and `0` otherwise.

Data Analysis

Type : SASHELP

The macro exclusively queries the `sashelp.vmacro` system view, which contains metadata on all existing macro variables in the SAS session. No other external data sources are used or created.

1 Code Block

Macro Logic (WHERE clause construction)

Explanation :
This first block initializes three local macro variables: `dsid` (for the dataset identifier), `rc` (for the return code), and `where` (for the filtering clause). It then constructs the `WHERE` clause that will be used to query the `sashelp.vmacro` view. If the `scope` parameter is provided, the search is limited to the specified scope, converted to uppercase. Otherwise, the search excludes the current macro's scope (`&sysmacroname`). Finally, the `WHERE` clause is completed to include the name of the macro variable to search for (`&mvar`), also converted to uppercase.

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1	%local dsid rc where;
2
3	%IF %LENGTH(&scope) %THEN %let where=scope=%upcase("&scope");
4	%ELSE %let where=scope ^= "&sysmacroname" ;
5	%let where=name=%upcase("&mvar") and &where;

2 Code Block

Macro Data Access Functionality

Explanation :
This second block executes the verification logic. It uses the `%sysfunc(open())` function to open the `sashelp.vmacro` system view, applying the previously defined `WHERE` clause. If the dataset is successfully opened (i.e., `&dsid` is not null), the macro attempts to retrieve a record using `%sysfunc(fetch(&dsid))`. If a record is found (indicated by a return code other than -1), it means the macro variable exists in the searched scope. The dataset is then closed with `%sysfunc(close(&dsid))`. The macro returns `1` if the macro variable is found and `0` otherwise.

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1	%let dsid = %sysfunc(open(sashelp.vmacro(where=(&where))));
2	%IF (&dsid) %THEN %DO;
3	%eval(%sysfunc(fetch(&dsid)) ^= -1)
4	%let rc = %sysfunc(close(&dsid));
5	%END;
6	%ELSE 0;

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