Make IO a class

samples/conway.cr

@@ -13,7 +13,7 @@ struct ANSI
   end
 end
 
-module IO
+class IO
   def ansi
     ANSI.new self
   end

spec/compiler/codegen/module_spec.cr

@@ -318,19 +318,19 @@ describe "Code gen: module" do
         end
       end
 
-      module IO2
+      module Moo
       end
 
-      module IO2::Sub
-        include IO2
+      module Moo::Sub
+        include Moo
       end
 
       class File2
-        include IO2::Sub
+        include Moo::Sub
       end
 
       file = File2.new
-      file2 = file.as(IO2)
+      file2 = file.as(Moo)
 
       file.method(file2)
       )).to_i.should eq(1)

spec/std/file_utils_spec.cr

@@ -1,9 +1,7 @@
 require "spec"
 require "file_utils"
 
-private class OneByOneIO
-  include IO
-
+private class OneByOneIO < IO
   @bytes : Bytes
 
   def initialize(string)

spec/std/http/server/server_spec.cr

@@ -1,12 +1,10 @@
 require "spec"
 require "http/server"
 
-private class RaiseErrno
+private class RaiseErrno < IO
   def initialize(@value : Int32)
   end
 
-  include IO
-
   def read(slice : Bytes)
     Errno.value = @value
     raise Errno.new "..."
@@ -17,9 +15,7 @@ private class RaiseErrno
   end
 end
 
-private class ReverseResponseOutput
-  include IO
-
+private class ReverseResponseOutput < IO
   @output : IO
 
   def initialize(@output : IO)

spec/std/io/buffered_spec.cr

@@ -1,6 +1,6 @@
 require "spec"
 
-private class BufferedWrapper
+private class BufferedWrapper < IO
   include IO::Buffered
 
   getter called_unbuffered_read

spec/std/io/delimited_spec.cr

@@ -1,8 +1,6 @@
 require "spec"
 
-private class PartialReaderIO
-  include IO
-
+private class PartialReaderIO < IO
   @slice : Bytes
 
   def initialize(data : String)

spec/std/io/io_spec.cr

@@ -5,9 +5,7 @@ require "base64"
 # This is a non-optimized version of IO::Memory so we can test
 # raw IO. Optimizations for specific IOs are tested separately
 # (for example in buffered_io_spec)
-private class SimpleIOMemory
-  include IO
-
+private class SimpleIOMemory < IO
   getter buffer : UInt8*
   getter bytesize : Int32
   @capacity : Int32

spec/std/io/sized_spec.cr

@@ -1,8 +1,6 @@
 require "spec"
 
-private class NoPeekIO
-  include IO
-
+private class NoPeekIO < IO
   def read(bytes : Bytes)
     0
   end

src/file/preader.cr

@@ -1,5 +1,5 @@
 # :nodoc:
-class File::PReader
+class File::PReader < IO
   include IO::Buffered
 
   getter? closed = false

src/flate/reader.cr

@@ -3,9 +3,7 @@
 # Instances of this class wrap another IO object. When you read from this instance
 # instance, it reads data from the underlying IO, decompresses it, and returns
 # it to the caller.
-class Flate::Reader
-  include IO
-
+class Flate::Reader < IO
   # If `#sync_close?` is `true`, closing this IO will close the underlying IO.
   property? sync_close : Bool
 

src/flate/writer.cr

@@ -5,9 +5,7 @@
 #
 # NOTE: unless created with a block, `close` must be invoked after all
 # data has been written to a Flate::Writer instance.
-class Flate::Writer
-  include IO
-
+class Flate::Writer < IO
   # If `#sync_close?` is `true`, closing this IO will close the underlying IO.
   property? sync_close : Bool
 

src/gzip/reader.cr

@@ -26,9 +26,7 @@
 # end
 # string # => "abc"
 # ```
-class Gzip::Reader
-  include IO
-
+class Gzip::Reader < IO
   # Whether to close the enclosed `IO` when closing this reader.
   property? sync_close = false
 

src/gzip/writer.cr

@@ -21,9 +21,7 @@
 #   end
 # end
 # ```
-class Gzip::Writer
-  include IO
-
+class Gzip::Writer < IO
   # Whether to close the enclosed `IO` when closing this writer.
   property? sync_close = false
 

src/http/content.cr

@@ -17,8 +17,7 @@ module HTTP
   end
 
   # :nodoc:
-  class UnknownLengthContent
-    include IO
+  class UnknownLengthContent < IO
     include Content
 
     def initialize(@io : IO)
@@ -46,8 +45,7 @@ module HTTP
   end
 
   # :nodoc:
-  class ChunkedContent
-    include IO
+  class ChunkedContent < IO
     include Content
     @chunk_remaining : Int32
 

src/http/server/response.cr

@@ -12,9 +12,7 @@ class HTTP::Server
   # are written and the connection `IO` (a socket) is yielded to the given block.
   # The block must invoke `close` afterwards, the server won't do it in this case.
   # This is useful to implement protocol upgrades, such as websockets.
-  class Response
-    include IO
-
+  class Response < IO
     # The response headers (`HTTP::Headers`). These must be set before writing to the response.
     getter headers : HTTP::Headers
 
@@ -136,7 +134,7 @@ class HTTP::Server
     end
 
     # :nodoc:
-    class Output
+    class Output < IO
       include IO::Buffered
 
       property! response : Response

src/http/web_socket/protocol.cr

@@ -42,9 +42,7 @@ class HTTP::WebSocket::Protocol
     @masked = !!masked
   end
 
-  class StreamIO
-    include IO
-
+  class StreamIO < IO
     def initialize(@websocket : Protocol, binary, frame_size)
       @opcode = binary ? Opcode::BINARY : Opcode::TEXT
       @buffer = Bytes.new(frame_size)

src/io.cr

@@ -5,9 +5,9 @@ require "c/sys/wait"
 require "c/errno"
 require "c/unistd"
 
-# The `IO` module is the basis for all input and output in Crystal.
+# The `IO` class is the basis for all input and output in Crystal.
 #
-# This module is included by types like `File`, `Socket` and `IO::Memory` and
+# This class is inherited by types like `File`, `Socket` and `IO::Memory` and
 # provide many useful methods for reading to and writing from an IO, like `print`, `puts`,
 # `gets` and `printf`.
 #
@@ -20,9 +20,7 @@ require "c/unistd"
 # For example, this is a simple `IO` on top of a `Bytes`:
 #
 # ```
-# class SimpleSliceIO
-#   include IO
-#
+# class SimpleSliceIO < IO
 #   def initialize(@slice : Bytes)
 #   end
 #
@@ -61,7 +59,7 @@ require "c/unistd"
 # Mixing string and byte operations might not give correct results and should be
 # avoided, as string operations might need to read extra bytes in order to get characters
 # in the given encoding.
-module IO
+abstract class IO
   # Argument to a `seek` operation.
   enum Seek
     # Seeks to an absolute location
@@ -1048,6 +1046,75 @@ module IO
     @encoding.try(&.name) || "UTF-8"
   end
 
+  # Seeks to a given *offset* (in bytes) according to the *whence* argument.
+  #
+  # The `IO` class raises on this method, but some subclasses, notable
+  # `IO::FileDescriptor` and `IO::Memory` implement it.
+  #
+  # Returns `self`.
+  #
+  # ```
+  # File.write("testfile", "abc")
+  #
+  # file = File.new("testfile")
+  # file.gets(3) # => "abc"
+  # file.seek(1, IO::Seek::Set)
+  # file.gets(2) # => "bc"
+  # file.seek(-1, IO::Seek::Current)
+  # file.gets(1) # => "c"
+  # ```
+  def seek(offset, whence : Seek = Seek::Set)
+    raise Error.new "Unable to seek"
+  end
+
+  # Returns the current position (in bytes) in this `IO`.
+  #
+  # The `IO` class raises on this method, but some subclasses, notable
+  # `IO::FileDescriptor` and `IO::Memory` implement it.
+  #
+  # ```
+  # File.write("testfile", "hello")
+  #
+  # file = File.new("testfile")
+  # file.pos     # => 0
+  # file.gets(2) # => "he"
+  # file.pos     # => 2
+  # ```
+  def pos
+    raise Error.new "Unable to pos"
+  end
+
+  # Sets the current position (in bytes) in this `IO`.
+  #
+  # The `IO` class raises on this method, but some subclasses, notable
+  # `IO::FileDescriptor` and `IO::Memory` implement it.
+  #
+  # ```
+  # File.write("testfile", "hello")
+  #
+  # file = File.new("testfile")
+  # file.pos = 3
+  # file.gets_to_end # => "lo"
+  # ```
+  def pos=(value)
+    raise Error.new "Unable to pos="
+  end
+
+  # Same as `pos`.
+  def tell
+    pos
+  end
+
+  # Yields an `IO` to read a section inside this IO.
+  #
+  # The `IO` class raises on this method, but some subclasses, notable
+  # `File` and `IO::Memory` implement it.
+  #
+  # Mutliple sections can be read concurrently.
+  def read_at(offset, bytesize, &block)
+    raise Error.new "Unable to read_at"
+  end
+
   # Copy all contents from *src* to *dst*.
   #
   # ```

src/io/argf.cr

@@ -1,7 +1,5 @@
 # :nodoc:
-class IO::ARGF
-  include IO
-
+class IO::ARGF < IO
   @path : String?
   @current_io : IO?
 

src/io/buffered.cr

@@ -1,12 +1,10 @@
-# The `IO::Buffered` mixin enhances the `IO` module with input/output buffering.
+# The `IO::Buffered` mixin enhances an `IO` with input/output buffering.
 #
 # The buffering behaviour can be turned on/off with the `#sync=` method.
 #
 # Additionally, several methods, like `#gets`, are implemented in a more
 # efficient way.
 module IO::Buffered
-  include IO
-
   BUFFER_SIZE = 8192
 
   @in_buffer_rem = Bytes.empty

src/io/console.cr

@@ -1,6 +1,6 @@
 require "termios"
 
-class IO::FileDescriptor
+class IO::FileDescriptor < IO
   # Turn off character echoing for the duration of the given block.
   # This will prevent displaying back to the user what they enter on the terminal.
   # Only call this when this IO is a TTY, such as a not redirected stdin.