(guile.info.gz) String Ports

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 27.9.2 String Ports
 -------------------
 
 The following allow string ports to be opened by analogy to R4R* file
 port facilities:
 
  -- Scheme Procedure: call-with-output-string proc
  -- C Function: scm_call_with_output_string (proc)
      Calls the one-argument procedure PROC with a newly created output
      port.  When the function returns, the string composed of the
      characters written into the port is returned.  PROC should not
      close the port.
 
  -- Scheme Procedure: call-with-input-string string proc
  -- C Function: scm_call_with_input_string (string, proc)
      Calls the one-argument procedure PROC with a newly created input
      port from which STRING's contents may be read.  The value yielded
      by the PROC is returned.
 
  -- Scheme Procedure: with-output-to-string thunk
      Calls the zero-argument procedure THUNK with the current output
      port set temporarily to a new string port.  It returns a string
      composed of the characters written to the current output.
 
  -- Scheme Procedure: with-input-from-string string thunk
      Calls the zero-argument procedure THUNK with the current input
      port set temporarily to a string port opened on the specified
      STRING.  The value yielded by THUNK is returned.
 
  -- Scheme Procedure: open-input-string str
  -- C Function: scm_open_input_string (str)
      Take a string and return an input port that delivers characters
      from the string. The port can be closed by `close-input-port',
      though its storage will be reclaimed by the garbage collector if
      it becomes inaccessible.
 
  -- Scheme Procedure: open-output-string
  -- C Function: scm_open_output_string ()
      Return an output port that will accumulate characters for
      retrieval by `get-output-string'. The port can be closed by the
      procedure `close-output-port', though its storage will be
      reclaimed by the garbage collector if it becomes inaccessible.
 
  -- Scheme Procedure: get-output-string port
  -- C Function: scm_get_output_string (port)
      Given an output port created by `open-output-string', return a
      string consisting of the characters that have been output to the
      port so far.
 
      `get-output-string' must be used before closing PORT, once closed
      the string cannot be obtained.
 
    A string port can be used in many procedures which accept a port but
 which are not dependent on implementation details of fports.  E.g.,
 seeking and truncating will work on a string port, but trying to
 extract the file descriptor number will fail.
 

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