On Sun, Sep 23, 2007 at 07:11:21PM -0700, Warren Harris wrote:
I have a simple output stream class that abstracts over out_channels and
buffers. I would like to add a printf method that takes a format directive,
and calls the appropriate Printf function.
[...]
This type parameter propagates through numerous places in my code,
in some cases requiring other methods to become polymorphic.
Consider using the class below instead of out_stream directly:
class my'out_stream och buf =
object
val buffer = new out_stream_of_buffer buf
method buffer = buffer
val outchan = new out_stream_of_channel och
method outchan = outchan
end
Or this one, depending on how you get your buf and och:
class my'out_stream'opt
?och ?buf () =
object (self)
val mutable buffer = None
method init_buffer buf =
buffer <- Some (new out_stream_of_buffer buf)
initializer
match buf with None -> ()
| Some buf -> self#init_buffer buf
method buffer =
match buffer with
| Some o -> o
| None -> failwith "MyStream.my'out_stream'opt#buf: no buffer provided"
val mutable outchan = None
method init_outchan och =
outchan <- Some (new out_stream_of_channel och)
initializer
match och with None -> ()
| Some och -> self#init_outchan och
method outchan =
match outchan with
| Some o -> o
| None -> failwith "MyStream.my'out_stream'opt#och: no channel provided"
end
HTH,
Julien.
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