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Diff for /gforth/doc/gforth.ds between versions 1.78 and 1.79

version 1.78, 2000/08/22 18:15:38 version 1.79, 2000/08/23 21:03:52
Line 7728  doc-get-order Line 7728  doc-get-order
 doc---gforthman-set-order  doc---gforthman-set-order
 doc-wordlist  doc-wordlist
 doc-table  doc-table
 doc-push-order  doc->order
 doc-previous  doc-previous
 doc-also  doc-also
 doc---gforthman-forth  doc---gforthman-forth
Line 7982  set-current Line 7982  set-current
 You can see what definitions are in the environment word list like this:  You can see what definitions are in the environment word list like this:
   
 @example  @example
 environment-wordlist push-order words previous  environment-wordlist >order words previous
 @end example  @end example
   
   
Line 10400  doc---objects-class Line 10400  doc---objects-class
 doc---objects-class->map  doc---objects-class->map
 doc---objects-class-inst-size  doc---objects-class-inst-size
 doc---objects-class-override!  doc---objects-class-override!
   doc---objects-class-previous
   doc---objects-class>order
 doc---objects-construct  doc---objects-construct
 doc---objects-current'  doc---objects-current'
 doc---objects-[current]  doc---objects-[current]
 doc---objects-current-interface  doc---objects-current-interface
 doc---objects-dict-new  doc---objects-dict-new
 doc---objects-drop-order  
 doc---objects-end-class  doc---objects-end-class
 doc---objects-end-class-noname  doc---objects-end-class-noname
 doc---objects-end-interface  doc---objects-end-interface
Line 10429  doc---objects-[parent] Line 10430  doc---objects-[parent]
 doc---objects-print  doc---objects-print
 doc---objects-protected  doc---objects-protected
 doc---objects-public  doc---objects-public
 @c !! push-order conflicts  
 doc---objects-push-order  
 doc---objects-selector  doc---objects-selector
 doc---objects-this  doc---objects-this
 doc---objects-<to-inst>  doc---objects-<to-inst>
Line 10733  doc---oof-class; Line 10732  doc---oof-class;
 @cindex mini-oof  @cindex mini-oof
   
 Gforth's third object oriented Forth package is a 12-liner. It uses a  Gforth's third object oriented Forth package is a 12-liner. It uses a
 mixture of the @file{object.fs} and the @file{oof.fs} syntax,  mixture of the @file{objects.fs} and the @file{oof.fs} syntax,
 and reduces to the bare minimum of features. This is based on a posting  and reduces to the bare minimum of features. This is based on a posting
 of Bernd Paysan in comp.lang.forth.  of Bernd Paysan in comp.lang.forth.
   
Line 10839  Object-oriented systems with late bindin Line 10838  Object-oriented systems with late bindin
 table, which contains the methods as function pointers. The vtable  table, which contains the methods as function pointers. The vtable
 may also contain other information.  may also contain other information.
   
 So first, let's declare methods:  So first, let's declare selectors:
   
 @example  @example
 : method ( m v -- m' v ) Create  over , swap cell+ swap  : method ( m v "name" -- m' v ) Create  over , swap cell+ swap
   DOES> ( ... o -- ... ) @@ over @@ + @@ execute ;    DOES> ( ... o -- ... ) @@ over @@ + @@ execute ;
 @end example  @end example
   
 During method declaration, the number of methods and instance  During selector declaration, the number of selectors and instance
 variables is on the stack (in address units). @code{method} creates  variables is on the stack (in address units). @code{method} creates one
 one method and increments the method number. To execute a method, it  selector and increments the selector number. To execute a selector, it
 takes the object, fetches the vtable pointer, adds the offset, and  takes the object, fetches the vtable pointer, adds the offset, and
 executes the @i{xt} stored there. Each method takes the object it is  executes the method @i{xt} stored there. Each selector takes the object
 invoked from as top of stack parameter. The method itself should  it is invoked with as top of stack parameter; it passes the parameters
   (including the object) unchanged to the appropriate method which should
 consume that object.  consume that object.
   
 Now, we also have to declare instance variables  Now, we also have to declare instance variables
   
 @example  @example
 : var ( m v size -- m v' ) Create  over , +  : var ( m v size "name" -- m v' ) Create  over , +
   DOES> ( o -- addr ) @@ + ;    DOES> ( o -- addr ) @@ + ;
 @end example  @end example
   
Line 10872  We need a starting point (the base objec Line 10872  We need a starting point (the base objec
   
 @example  @example
 Create object  1 cells , 2 cells ,  Create object  1 cells , 2 cells ,
 : class ( class -- class methods vars ) dup 2@@ ;  : class ( class -- class selectors vars ) dup 2@@ ;
 @end example  @end example
   
 For inheritance, the vtable of the parent object has to be  For inheritance, the vtable of the parent object has to be
Line 10880  copied when a new, derived class is decl Line 10880  copied when a new, derived class is decl
 methods of the parent class, which can be overridden, though.  methods of the parent class, which can be overridden, though.
   
 @example  @example
 : end-class  ( class methods vars -- )  : end-class  ( class selectors vars "name" -- )
   Create  here >r , dup , 2 cells ?DO ['] noop , 1 cells +LOOP    Create  here >r , dup , 2 cells ?DO ['] noop , 1 cells +LOOP
   cell+ dup cell+ r> rot @@ 2 cells /string move ;    cell+ dup cell+ r> rot @@ 2 cells /string move ;
 @end example  @end example
Line 10892  copies the xts from the parent vtable. Line 10892  copies the xts from the parent vtable.
 We still have no way to define new methods, let's do that now:  We still have no way to define new methods, let's do that now:
   
 @example  @example
 : defines ( xt class -- ) ' >body @@ + ! ;  : defines ( xt class "name" -- ) ' >body @@ + ! ;
 @end example  @end example
   
 To allocate a new object, we need a word, too:  To allocate a new object, we need a word, too:
Line 10940  Now, implement the two methods, @code{dr Line 10940  Now, implement the two methods, @code{dr
   
 @noindent  @noindent
 To demonstrate inheritance, we define a class @code{bold-button}, with no  To demonstrate inheritance, we define a class @code{bold-button}, with no
 new data and no new methods:  new data and no new selectors:
   
 @example  @example
 button class  button class
Line 10960  for @code{button}: Line 10960  for @code{button}:
 @end example  @end example
   
 @noindent  @noindent
 Finally, create two objects and apply methods:  Finally, create two objects and apply selectors:
   
 @example  @example
 button new Constant foo  button new Constant foo
Line 11001  to pass objects on the stack. Line 11001  to pass objects on the stack.
   
 @item  @item
 It requires that the selector parses the input stream (at  It requires that the selector parses the input stream (at
 compile time); this leads to reduced extensibility and to bugs that are+  compile time); this leads to reduced extensibility and to bugs that are
 hard to find.  hard to find.
   
 @item  @item
 It allows using every selector to every object;  It allows using every selector on every object; this eliminates the
 this eliminates the need for classes, but makes it harder to create  need for interfaces, but makes it harder to create efficient
 efficient implementations.   implementations.
 @end itemize  @end itemize
   
 @cindex Pountain's object-oriented model  @cindex Pountain's object-oriented model
Line 11018  binding. Instead, it focuses on features Line 11018  binding. Instead, it focuses on features
 overloading that are characteristic of modular languages like Ada (83).  overloading that are characteristic of modular languages like Ada (83).
   
 @cindex Zsoter's object-oriented model  @cindex Zsoter's object-oriented model
 In @cite{Does late binding have to be slow?} (Forth Dimensions 18(1)  In @uref{http://www.forth.org/oopf.html, Does late binding have to be
 1996, pages 31-35) Andras Zsoter describes a model that makes heavy use  slow?} (Forth Dimensions 18(1) 1996, pages 31-35) Andras Zsoter
 of an active object (like @code{this} in @file{objects.fs}): The active  describes a model that makes heavy use of an active object (like
 object is not only used for accessing all fields, but also specifies the  @code{this} in @file{objects.fs}): The active object is not only used
 receiving object of every selector invocation; you have to change the  for accessing all fields, but also specifies the receiving object of
 active object explicitly with @code{@{ ... @}}, whereas in  every selector invocation; you have to change the active object
 @file{objects.fs} it changes more or less implicitly at @code{m:  explicitly with @code{@{ ... @}}, whereas in @file{objects.fs} it
 ... ;m}. Such a change at the method entry point is unnecessary with the  changes more or less implicitly at @code{m: ... ;m}. Such a change at
 Zsoter's model, because the receiving object is the active object  the method entry point is unnecessary with Zsoter's model, because the
 already. On the other hand, the explicit change is absolutely necessary  receiving object is the active object already. On the other hand, the
 in that model, because otherwise no one could ever change the active  explicit change is absolutely necessary in that model, because otherwise
 object. An ANS Forth implementation of this model is available at  no one could ever change the active object. An ANS Forth implementation
 @uref{http://www.forth.org/fig/oopf.html}.  of this model is available through
   @uref{http://www.forth.org/oopf.html}.
   
 @cindex @file{oof.fs}, differences to other models  @cindex @file{oof.fs}, differences to other models
 The @file{oof.fs} model combines information hiding and overloading  The @file{oof.fs} model combines information hiding and overloading
Line 11768  doc-getenv Line 11769  doc-getenv
 @section Keeping track of Time  @section Keeping track of Time
 @cindex time-related words  @cindex time-related words
   
 Gforth implements time-related operations by making calls to the C  
 library function, @code{gettimeofday}.  
   
 doc-ms  doc-ms
 doc-time&date  doc-time&date
   doc-utime
   doc-cputime
   
   
 @c -------------------------------------------------------------  @c -------------------------------------------------------------
Line 11810  in file included from ./yyy.fs:1 Line 11809  in file included from ./yyy.fs:1
 ./xxx.fs:4: Invalid memory address  ./xxx.fs:4: Invalid memory address
 bar  bar
 ^^^  ^^^
   Backtrace:
 $400E664C @@  $400E664C @@
 $400E6664 foo  $400E6664 foo
 @end example  @end example
Line 11857  case. Line 11857  case.
 @cindex @code{gforth-fast}, difference from @code{gforth}  @cindex @code{gforth-fast}, difference from @code{gforth}
 @cindex backtraces with @code{gforth-fast}  @cindex backtraces with @code{gforth-fast}
 @cindex return stack dump with @code{gforth-fast}  @cindex return stack dump with @code{gforth-fast}
 @code{gforth} is able to do a return stack dump for throws generated  @code{Gforth} is able to do a return stack dump for throws generated
 from primitives (e.g., invalid memory address, stack empty etc.);  from primitives (e.g., invalid memory address, stack empty etc.);
 @code{gforth-fast} is only able to do a return stack dump from a  @code{gforth-fast} is only able to do a return stack dump from a
 directly called @code{throw} (including @code{abort} etc.).  This is the  directly called @code{throw} (including @code{abort} etc.).  This is the
Line 12067  If @code{WORD} is called with the space Line 12067  If @code{WORD} is called with the space
 white-space characters (as identified by the C macro @code{isspace()})  white-space characters (as identified by the C macro @code{isspace()})
 are delimiters. @code{PARSE}, on the other hand, treats space like other  are delimiters. @code{PARSE}, on the other hand, treats space like other
 delimiters. @code{SWORD} treats space like @code{WORD}, but behaves  delimiters. @code{SWORD} treats space like @code{WORD}, but behaves
 like @code{PARSE} otherwise. @code{(NAME)}, which is used by the outer  like @code{PARSE} otherwise. @code{Name}, which is used by the outer
 interpreter (aka text interpreter) by default, treats all white-space  interpreter (aka text interpreter) by default, treats all white-space
 characters as delimiters.  characters as delimiters.
   
Line 12110  lines. One of these characters is typica Line 12110  lines. One of these characters is typica
 @cindex maximum size of a counted string  @cindex maximum size of a counted string
 @cindex counted string, maximum size  @cindex counted string, maximum size
 @code{s" /counted-string" environment? drop .}. Currently 255 characters  @code{s" /counted-string" environment? drop .}. Currently 255 characters
 on all ports, but this may change.  on all platforms, but this may change.
   
 @item maximum size of a parsed string:  @item maximum size of a parsed string:
 @cindex maximum size of a parsed string  @cindex maximum size of a parsed string
Line 12147  What are we expected to document here? Line 12147  What are we expected to document here?
 @cindex number of bits in one address unit  @cindex number of bits in one address unit
 @cindex address unit, size in bits  @cindex address unit, size in bits
 @code{s" address-units-bits" environment? drop .}. 8 in all current  @code{s" address-units-bits" environment? drop .}. 8 in all current
 ports.  platforms.
   
 @item number representation and arithmetic:  @item number representation and arithmetic:
 @cindex number representation and arithmetic  @cindex number representation and arithmetic
 Processor-dependent. Binary two's complement on all current ports.  Processor-dependent. Binary two's complement on all current platforms.
   
 @item ranges for integer types:  @item ranges for integer types:
 @cindex ranges for integer types  @cindex ranges for integer types
Line 12182  string. Line 12182  string.
   
 @item size of one character in address units:  @item size of one character in address units:
 @cindex char size  @cindex char size
 @code{1 chars .}. 1 on all current ports.  @code{1 chars .}. 1 on all current platforms.
   
 @item size of the keyboard terminal buffer:  @item size of the keyboard terminal buffer:
 @cindex size of the keyboard terminal buffer  @cindex size of the keyboard terminal buffer
Removed from v.1.78  
changed lines
  Added in v.1.79

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