Class: Stream::ImplicitStream

### Home Classes Methods

### In Files

- lib/stream.rb

### Parent

Stream::BasicStream

### Methods

- ::new
- #at_beginning?
- #at_end?
- #basic_backward
- #basic_forward
- #set_to_begin
- #set_to_end

### Class/Module Index

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# Stream::ImplicitStream

An ImplicitStream is an easy way to create a stream on the fly without defining a subclass of BasicStream. The basic methods required for a stream are defined with blocks:

    s = Stream::ImplicitStream.new { |s|
               x = 0
               s.at_end_proc = proc {x == 5}
               s.forward_proc = proc {x += 1 }
        }

    s.to_a ==> [1, 2, 3, 4, 5]

Note that this stream is only partially defined since backward_proc and at_beginning_proc are not defined. It may as well be useful if only moving forward is required by the code fragment.

ImplicitStreams can be based on other streams using the method modify which is for example used in the methods for creating stream wrappers which remove the first or last element of an existing stream (see remove_first and remove_last).

### Attributes

at_beginning_proc[W]
at_end_proc[W]
backward_proc[W]
forward_proc[W]
set_to_begin_proc[W]
set_to_end_proc[W]
wrapped_stream[R]

### Public Class Methods

new(otherStream=nil) click to toggle source

Create a new ImplicitStream which might wrap an existing stream otherStream. If otherStream is supplied the blocks for the basic stream methods are initialized with closures that delegate all operations to the wrapped stream.

If a block is given to new, than it is called with the new ImplicitStream stream as parameter letting the client overwriting the default blocks.

    # File lib/stream.rb, line 470
    def initialize (otherStream=nil)
      if otherStream
            @wrapped_stream = otherStream
            @at_beginning_proc = proc {otherStream.at_beginning?}
            @at_end_proc = proc {otherStream.at_end?}
            @forward_proc = proc {otherStream.basic_forward}
            @backward_proc = proc {otherStream.basic_backward}
            @set_to_end_proc = proc {otherStream.set_to_end}
            @set_to_begin_proc = proc {otherStream.set_to_begin}
      end
      yield self if block_given? # let client overwrite defaults

      @at_beginning_proc = proc {true} unless @at_beginning_proc
      @at_end_proc = proc {true} unless @at_end_proc
    end

### Public Instance Methods

at_beginning?() click to toggle source

Returns the value of @at_beginning_proc.

    # File lib/stream.rb, line 487
    def at_beginning?; @at_beginning_proc.call; end

at_end?() click to toggle source

Returns the value of @at_end_proc.

    # File lib/stream.rb, line 489
    def at_end?; @at_end_proc.call; end

basic_backward() click to toggle source

Returns the value of @backward_proc_proc.

    # File lib/stream.rb, line 494
    def basic_backward; @backward_proc.call; end

basic_forward() click to toggle source

Returns the value of @forward_proc.

    # File lib/stream.rb, line 492
    def basic_forward; @forward_proc.call; end

set_to_begin() click to toggle source

Calls set_to_begin_proc or super if set_to_begin_proc is undefined.

    # File lib/stream.rb, line 502
    def set_to_begin
      @set_to_begin_proc ? @set_to_begin_proc.call : super
    end

set_to_end() click to toggle source

Calls set_to_end_proc or super if set_to_end_proc is undefined.

    # File lib/stream.rb, line 497
    def set_to_end
      @set_to_end_proc ? @set_to_end_proc.call : super
    end

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