J3/06-142

Date:    2006/02/16
To:      J3
From:    Malcolm Cohen
Subject: Edits for Intelligent Macros part 1
References: J3/06-123r1.

1. Introduction

This paper provides partial edits for Intelligent Macros (item J3-014);
this part is the BLOCK construct.
The specifications and syntax were in paper 06-123r1.

2. Notes

3. Edits to 04-007

[xiii] Add new feature
  "The BLOCK construct (allows declarations within executable statements)."

[10:53+] 2.1 High level syntax, R213 executable-construct, add new production
in alphabetic order
  "<<or>> <block-construct>"

[17:6] 2.4.3.1.1 Variable, second paragraph, after "or host association."
insert new sentence
  "A named local variable of a BLOCK construct is a named variable that is
   declared in that construct, is not in COMMON, does not have the BIND
   attribute, and is not accessed by use association."
{Call construct entities that are variables, local variables of the construct.
 We don't have to consider host association, because a BLOCK construct is not
 a scoping unit and therefore doesn't use host association.}

[28:4+something] 3.3.1 Free source form, "Adjacent keywords..." table,
  insert into table "END BLOCK".
{Make blanks between these keywords optional in free form.}

[59:24+] 4.5.5.2 When finalization occurs, after second paragraph, insert new
paragraph
  "A nonpointer nonallocatable local variable of a BLOCK construct is finalized
   immediately before it would become undefined due to termination of the BLOCK
   construct (16.5.6, item (19))."
{Block construct entities can be finalised.}

[115:8+] 6.3.3.1 Deallocation of allocatable variables, after second paragraph,
insert new paragraph
  "When a BLOCK construct terminates, an allocatable variable that is a named
   local variable of the construct retains its allocation and definition status
   if it has the SAVE attribute; otherwise it is deallocated."

[155:6+] 8.1 Executable constructs containing blocks, first paragraph,
numbered list, insert new list item in alphabetic order
  "(1a) BLOCK construct".

[169:1-] Immediately before 8.2 Branching, insert new subclause
  "8.1.7 BLOCK construct

   The BLOCK construct is a block which may contain declarations.

   R8m1 <block-construct> <<is>> <block-stmt>
                                   <specification-part>
                                   <block>
                                 <end-block-stmt>

   R8m2 <block-stmt> <<is>> [ <block-construct-name> : ] BLOCK

   R8m3 <end-block-stmt> <<is>> END BLOCK [ <block-construct-name> ]

   C8m1 (R8m1) If the <block-stmt> of a <block-construct> specifies a
        <block-construct-name>, the corresponding <end-block-stmt> shall
        specify the same <block-construct-name>.  If the <block-stmt> does not
	specify a <block-construct-name>, the corresponding <end-block-stmt>
        shall not specify a <block-construct-name>.

   Specifications in a BLOCK construct declare construct entities whose scope
   is that of the BLOCK construct.

   Specification expressions in the <specification-part> are evaluated when the
   BLOCK statement is executed.

   The BLOCK construct terminates when:
   (a) a RETURN statement within the block is executed, or
   (c) transfer of control to a statement outside the block occurs."

[409:16+] 16.3 Statement and construct entities, first paragraph, append new
sentence:
  "An entity that is declared in a BLOCK construct and is not accessed by use
   association is a construct entity."
{BLOCK constructs contain construct entities.}

[410:14+] 16.3, append paragraph to subclause
  "If a global or local identifier accessible in the scoping unit of a BLOCK
   construct is the same as a construct entity of that BLOCK construct, the
   name is interpreted within the BLOCK construct as that of the construct
   entity."
{Usual rules for hiding outer entities when you have a construct entity.  We
 could probably finesse these... they are stated once per type of construct,
 which seems overly redundant.}

[420:2] 16.5.3 Variables that are initially defined, item (3),
change "either saved or are declared in a main program, MODULE,"
to "saved, local variables of a main program, or declared in a MODULE".
{BLOCK construct entities are declared "in" a main program, but that does
 not make them implicitly saved.}

[421:43+] 16.5.5 Events that cause variables to become defined, append new item
  "(27) Execution of the BLOCK statement of a BLOCK construct that has an
        unsaved nonpointer nonallocatable local variable causes all nonpointer
        default-initialized subcomponents of the variable to become defined."
{Default-initialize unsaved construct entities on entry to the construct.}

[423:28+] 16.5.6 Events that cause variables to become undefined, append new
item
  "(19) When a BLOCK construct terminates, its unsaved local variables become
        undefined."

[427:24] Annex A, "construct" definition, before "DO" insert "BLOCK".
{Add BLOCK constructs to the list of constructs.}

===END===