ic.0

Object-Oriented Programming With ANSI-C这本书中的源代码!找了很久

Ic(4)                                                       Ic(4)


NAME
       IcClass:  Class   Ic: Objct -- basic input/output/transput
       objects

SYNOPSIS
       Objct
           Ic
               Button
               Calc
               LineOut
               Mux
       new(Ic());
       new(Button(), "text");
       new(Calc());
       new(LineOut());
       new(Mux());
       %-
       void wire (Objct @ to, self)
       enum { reject, accept } gate (self, const void * item)

DESCRIPTION
       An Ic object has  an  output  pin  and  an  input  action.
       wire() connects the output to some other object.  If an Ic
       object is sent a data item with gate(),  it  will  perform
       some  action  and send some result to its output pin; some
       Ic objects only create  output  and  others  only  consume
       input.   gate() returns accept if the receiver accepts the
       data.

       Ic is a base class.  Subclasses overwrite gate() to imple-
       ment  their own processing.  Ic_gate() takes item and uses
       gate() to send it on to the output pin, i.e.,  a  subclass
       will use super_gate() to send something to its output pin.

       A Button object contains a  text  which  is  sent  out  in
       response to certain inputs.  It expects an Event object as
       input.  If the Event contains a matching text  or  a  null
       pointer  or  other  data, the Button accepts the input and
       sends its own text on.  A non-matching text is rejected.

       Button is designed as a  base  class.   Subclasses  should
       match  mouse positions, etc., and use super_gate() to send
       out the appropriate text.

       A Calc object receives a string, computes  a  result,  and
       sends  the current result on as a string.  The first char-
       acter of the input string is processed: digits are  assem-
       bled  into  a  non-negative decimal number; +, -, *, and /
       perform arithmetic operations on two operands; = completes
       an  arithmetic  operation;  C resets the calculator; and Q
       quits the application.  The calculator is a simple, prece-
       dence-free,  finite state machine: the first set of digits
       defines a first operand; the first operator is saved; more
       digits  define  another  operand;  if  another operator is



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Ic(4)                                                       Ic(4)


       received, the saved operator is executed and the new oper-
       ator  is  saved.  Invalid inputs are accepted and silently
       ignored.

       A LineOut object accepts a string and displays it.

       A Mux object can be wired to a list of outputs.  It  sends
       its  input  to  each  of  these  outputs until one of them
       accepts the input.  The list  is  built  and  searched  in
       order of the wire() calls.

SEE ALSO
       Crt(4), Event(4), Xt(4)












































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