Comments on Porting
                      Dynamic String Package
                           by WIS JPMO                
                            to DEC Ada

                                                                Tool 29 
                                                                August 20, 1985
     
COMPILATION
-----------
  The file DYN.SRC which composed the Dynamic String package was recompiled 
  with a few changes.

  1.  The type "long-integer" is not available on DEC, therefore type "integer"
      was substituted and type "short_integer" was used in place of type 
      "integer".
      
  2.  INTEGER_IO and FLOAT_IO were incorporated by using the predefined 
      instantiations, FLOAT_TEXT_IO and INTEGER_TEXT_IO.
         
  3.  The private definition of DYN_STRING for a validated compiler was to 
      allow the discriminant, the string size, to change frequently.  In order
      to accomplish this, a default value was required initially and each 
      change was then made with a complete record assignment.  However, this
      definition raised a numeric error during elaboration.  We tried this on 
      VERDIX and raised the same error, VERDIX contends it is a 'bug'. 

      We later tried the following definition and had no problem. 

             subtype INDEX is positive range 1..100;
             type DYN_STRING (SIZE : INDEX := 1) is private; 

             private
                   type DYN_STRING (size : index := 1) is
                      record
                          DATA : string (1..size);
                      end record;

      Note, this constrains the maximum allocation size of the string but  
      still allows the string to be dynamic. 

      The original method, to be used when a validated compiler was not
      available, worked fine.
      
      

EXECUTION
---------
  We were able to execute a program that used the Dynamic String Package and 
  it appeared to be in workable condition.