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Description

Function identifiers are identifiers that have been associated with a function using a function declaration.

Example

Here is an example of a function declaration.

 //This function checks whether a files exists. Actually it really checks
 //to see if a file can be opened for reading without causing an error,
 //which is usually the same thing. The function first turns off run-time error
 //trapping so that if an error occurs it can be retrieved with getlasterror
 //rather than causing the program to halt. Then the function attempts to
 //open the file for reading. If no errors occur then the file is closed and
 //the file must exist. If an error occurs then the function assumes the file
 //does not exist. In either case error trapping it turned back on before the
 //function exits.
 function FileExists(name : filename) : boolean;
 var
  f : text;
 begin (* FileExists *)
  traperrors(false);
  reset(f, name);
  if getlasterror=0 then
   begin
    close(f);
    FileExists := true;
   end
  else
   FileExists := false;
  traperrors(true)
 end; (* FileExists *)

Syntax

(NOTE: for clarity some parts of the syntax are omitted, see Irie Pascal Grammar for the full syntax):

   function-declaration =
       function-heading ';' directive |
       function-identification ';' function-block |
       function-heading ';' function-block

   block = declarative-part statement-part

   compound-statement = 'begin' statement-sequence 'end'

   declaration-group =
             label-declaration-group |
             constant-definition-group |
             type-definition-group |
             variable-declaration-group |
             function-declaration  | 
             procedure-declaration

   declarative-part = { declaration-group }

   directive = forward-directive | external-directive

   formal-parameter-list = '(' formal-parameter-section { ';' formal-parameter-section } ')'

   formal-parameter-section = value-parameter-specification |
                  variable-parameter-specification |
                  procedure-parameter-specification |
                  function-parameter-specification

   function-block = block

   function-heading = 'function' identifier [ formal-parameter-list ] ':' result-type

   function-identification = 'function' function-identifier

   function-identifier = identifier

   function-parameter-specification = function-heading

   identifier = letter { letter | digit }

   identifier-list = identifier { ',' identifier }

   procedure-heading = 'procedure' identifier [ formal-parameter-list ]

   procedure-identification = 'procedure' procedure-identifier

   procedure-identifier = identifier

   procedure-parameter-specification = procedure-heading

   result-type = type-identifier

   statement-part = compound-statement

   statement-sequence = statement { ';' statement }

   type-identifier = identifier

   value-parameter-specification = identifier-list ':' type-identifier

   variable-parameter-specification = 'var' identifier-list ':' type-identifier