Aminet 24/Aminet 24 (1998)(GTI - Schatztruhe)[!][Apr 1998].iso/Aminet/dev/lang/PPCsmalltalk.lha/PPCSmallTalk/docs/manbody

Text File | 1986-10-19 | 28KB | 1,350 lines

                 AAAA LLLLiiiittttttttlllleeee SSSSmmmmaaaallllllllttttaaaallllkkkk UUUUsssseeeerrrr MMMMaaaannnnuuuuaaaallll


                        Timothy A. Budd






  _1.  _I_n_t_r_o_d_u_c_t_i_o_n

       This manual is intended as an aid in using  the  Little
  Smalltalk  system.   It  is  not  intended  to be used as an
  introduction to the Smalltalk language.  Little Smalltalk is
  largely (with exceptions listed in a later section) a subset
  of  the  Smalltalk-80*  language  described  in  [.Smalltalk
  blue.].   A  complete description of the classes included in
  the Little Smalltalk system and the messages they accept  is
  given in Appendix 1.

  _2.  _R_u_n_n_i_n_g _t_h_e _s_y_s_t_e_m

       The Little Smalltalk system is invoked  by  typing  the
  command  sssstttt.   The system is interactive - that is, the user
  types an expression at the keyboard and the system  responds
  by  evaluating  the  expression  and typing the result.  For
  example, typing the expression 3333 ++++ 4444 results in the value  7777
  being  displayed  on the output.  Execution is terminated by
  typing control-D.  A sample execution session  is  shown  in
  Figure 1.


                        % st
                        Little Smalltalk
                                3 + 4
                        7
                                ^D
                        %


          FFFFiiiigggguuuurrrreeee 1111:::: A Sample Little Smalltalk Session


       Instance variables for the command level can be created
  by  assigning  a  value  to a new variable name.  Thereafter
  that variable can be used at the command level, although  it
  is  not  known within the scope of any method.  The variable
  _________________________
  * Smalltalk-80 is a trademark of the Xerox Corporation.




                       September 19, 1986





                             - 2 -


  ``last'' always contains the  value  returned  by  the  last
  expression  typed.   Figure  2 shows the creation of a vari-
  able.  Note that the assignment arrow is  formed  as  a  two
  character sequence.


                    newvar <- 2 / 3
                    newvar
               0.666667
                    2 raisedTo: newvar + (4 / 3)
               4
                    last
               4


                  FFFFiiiigggguuuurrrreeee 2222:::: Creating Variables


       The default behavior is for the value  of  expressions,
  with the exception of assignments, to be typed automatically
  as they are evaluated.  This behavior can be modified either
  by  using the -d flag (see Appendix 2), or by passing a mes-
  sage to the pseudo variable ssssmmmmaaaallllllllttttaaaallllkkkk (see Appendix 1).

       Class descriptions must be read  in  from  files,  they
  cannot  be  entered  interactively.   Class descriptions are
  entered using a system directive.  For example, to include a
  class description contained in a file named nnnneeeewwwwccccllllaaaassssssss....sssstttt, the
  following system directive should be issued:

                         )i newclass.st

  A list of files containing class descriptions  can  also  be
  given as arguments to the st command.  The command

                      %st file1 ... filen
  is equivalent to the sequence

                        %st
                        Little Smalltalk
                             )i file1
                             ...
                             )i filen

       A table of system directives is given in Figure 3.

       Note that the )e system directive invokes an editor  on
  a file containing class descriptions, and then automatically
  includes the file when the editor is  exited.  Classes  also
  respond to the message eeeeddddiiiitttt, which will have the same effect
  as the )e directive applied to the file containing the class
  description.    Thus   the  typical  debug/edit/debug  cycle



                       September 19, 1986





                             - 3 -




  _____________________________________________________________

   )e filename
                 Edit the named file.   The  Little  Smalltalk
                 system  will  suspend, leaving the user in an
                 editor for making changes to the named  file.
                 Upon  leaving  the editor the named file will
                 automatically  be  included,  as  if  the  )i
                 directive had been typed.

   )g filename
                 Search for an entry  in  the  system  library
                 area  matching  the  filename.  If found, the
                 class descriptions in the library  entry  are
                 included.    This   command   is  useful  for
                 including commonly used classes that are  not
                 part of the standard prelude, such as classes
                 for statistics applications or graphics.

   )i filename
                 Include  the  named  file.   The  file   must
                 contain  one or more class descriptions.  The
                 class  descriptions  are   parsed,   and   if
                 syntactically  legal  new  instances of class
                 CCCCllllaaaassssssss are added to the Smalltalk system.

   )l filename
                 Load a previously saved environment from  the
                 named   file.   The  current  values  of  all
                 variables are overridden.  The file must have
                 been created using the )s directive (below).

   )r filename
                 Read the named file.  The file  must  contain
                 Smalltalk  statements,  as  would be typed at
                 the keyboard.  The effect is just as  if  the
                 lines  of  the  file  had  been  typed at the
                 keyboard.   The  file  cannot  contain  class
                 descriptions.

   )s filename
                 Save the current state  in  the  named  file.
                 The  values  of  all variables are saved, and
                 can later be reloaded using the )l  directive
                 (above).

   )!string
                 Execute the remainder of the  line  following
                 the  exclamation  point  as  a Unix* command.
                 Nothing  is  done  with  the  output  of  the
                 command,  nor  is the returning status of the
                 command recorded.

  _____________________________________________________________
  ||||||||||||||||||||||||||||||||||||||||||||||











































                                                               ||||||||||||||||||||||||||||||||||||||||||||||














































                  FFFFiiiigggguuuurrrreeee 3333:::: System Directives






                       September 19, 1986





                             - 4 -


  involves repeated uses of the )e directive or the eeeeddddiiiitttt  mes-
  sage  until  a  desired  outcome  is  achieved.   The editor
  invoked by the )e directive can be changed  by  setting  the
  EDITOR variable in the users environment.

  _3.  _D_i_f_f_e_r_e_n_c_e_s _b_e_t_w_e_e_n _L_i_t_t_l_e _S_m_a_l_l_t_a_l_k _a_n_d _t_h_e  _S_m_a_l_l_t_a_l_k-
  _8_0 _s_y_s_t_e_m

       This section  describes  the  differences  between  the
  language  accepted  by  the  Little Smalltalk system and the
  language described in  [.Smalltalk  blue.].   The  principal
  reasons for these changes are as follows:

  size  Classes which are largely unnecessary, or which  could
        be  easily  simulated  by other classes (e.g. Associa-
        tion, SortedCollection) have been  eliminated  in  the
        interest  of  keeping the size of the standard library
        as smal