# AUTO\_EXTERN

> [HTML Version](auto_extern.htm)

**\++PRAGMA AUTO\_EXTERN \{"<boolean>"\} **

Enables or disables the visibility (with the local function or procedure) of variables defined globally—i.e. with standard MAP statements outside any function or procedure. The argument defaults to "TRUE", so the following are equivalent:

\++PRAGMA AUTO\_EXTERN "TRUE"

\++PRAGMA AUTO\_EXTERN

\++pragma auto\_extern          \! pragmas are case insensitive



The setting is reset to FALSE at the start of each function or procedure, so must be specified whenever you want to reference global variables within a routine. The only point of specifying an argument of "FALSE" would be if you first enabled it, then later in the function didn't have any further need to reference global variables and wanted to protect against accidentally doing so. 

**Example**

PROCEDURE MYPROC(p1 as f)

\++PRAGMA AUTO\_EXTERN           \! expose all global vars to this procedure

   ...

   SOME'VAR = SOME'VAR + p1    \! add parameter p1 to global variable SOME'VAR

   ...

ENDPROCEDURE



The above technique, while undermining one of the benefits of using PROCEDURE as opposed to old-style GOSUBs, does provide a convenient way to migrate from unstructured GOSUBs to structured PROCEDURES. Essentially all you need to do to convert a reasonably well-designed GOSUB into a proper PROCEDURE is to add the PROCEDURE keyword, an empty parameter list, the AUTO\_EXTERN pragma, remove the RETURN, and add the ENDPROCEDURE, e.g.  

The following GOSUB ...

MYPROC:

   ...

   RETURN



can be converted to a PROCEDURE as follows:

PROCEDURE MYPROC()

\++PRAGMA AUTO\_EXTERN 

   ...

   \! RETURN    \! (RETURN may also be converted to EXITPROCEDURE)

ENDPROCEDURE



Note that the above illustration ignores certain issues that may complicate such conversions. If the GOSUB has RETURN statements other than at the physical end, these can be converted to EXITPROCEDURE statements. But a PROCEDURE may not contain GOSUB (or CALL) statements to other old-style GOSUB routines, so they would have to be converted as well. Also, any GOSUB MYPROC (or CALL MYPROC) statements referencing the original routine would have to be converted to CALL MYPROC. These are all fairly mechanical steps though, after which you would be in position to incrementally access the modularization/isolation/encapsulation advantages of proper procedures with local variables and true parameter passing.

**See Also**

•	[EXTERN](extern_statements.md)