J3/04-108


Date:    08 Dec. 2003
To:      J3
From:    Dan Nagle
Subject: Name of Block Should Have Scope of Block


The name of a block should have the scope of the block.

Number:

Title: Name of Block Has Scope of Block

Submitted By: J3

Status: For Consideration

References:

Basic Functionality: Give the name of a block the scope of the block,
      rather than the local scoping unit scope it now has.  This will
      allow, for example, blocks to be labeled 'read_error:' etc.
      without error (which is consistent with copy-and-paste editing).

Rationale:  Block names are not referenced outside the block,
            so there is no reason to give then local scope.
            Inventing a block scope allows block names to be repeated
            within a local scope, so names like 'open_error:' or
            'planes_loop:' may be re-used.

Estimated Impact: Low, no use of block names is made outside the block.
          Other proposals have been mentioned for block level
          variables scope, so this feature may 'piggy-back' along
          with that one.  EXIT and CYCLE are unaffected, as they
          operate from within the block.

Detailed Specification: A new scope, that of a block (if, do, etc.)
         will be invented and names of blocks given this scope.

         Example:

         ! open first input file
         open( ... , iostat= istatvar, ...)
         open_error: if( istatvar > 0 )then
            ! do something
         endif open_error
         ! open second input file
         open( ... , iostat= istatvar, ...)
         open_error: if( istatvar > 0 )then
            ! do something
         endif open_error

History: