[Caml-list] errors compiling thrift-generated code

[Caml-list] errors compiling thrift-generated code

[Joel Reymont]

Folks,

Any suggestions on what's going on here?

https://gist.github.com/876154

The error is at the very bottom.

This is code auto-generated by Apache Thrift.

	Thanks, Joel

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[Caml-list] Re: errors compiling thrift-generated code

[Joel Reymont]

Changing the copy method to this 

  method copy =
    let _new = (Oo.copy self:> #document) in
   _new

or this:

  method copy : document =
    let _new = Oo.copy self in
   _new

gives the error at the very bottom of the gist [1], i.e. "Self type cannot escape its class"

	Thanks, Joel

[1] https://gist.github.com/876154

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Re: [Caml-list] errors compiling thrift-generated code

[Niki Yoshiuchi]

Apologies if you receive this twice, I accidentally hit reply instead
of reply all.

The problem appears to be related to the problem that self is
dynamically bound at invocation (as objects can be extended by
subclasses).  The details are outlined here:
http://caml.inria.fr/pub/docs/manual-ocaml/manual005.html#toc20
You'll noticed that if you declare an object with a reference to self
its type is:

   class myclass : object ('a) .... : ;a end

In other words, self is of type 'a and not type myclass.

The easiest way to fix your problem is to change the interface so that:

   method copy : document

becomes:

   method copy : 'a

You should also file a bug report with the Thrift developers.

-Niki Yoshiuchi

On Fri, Mar 18, 2011 at 10:29 AM, Joel Reymont <joelr1@gmail.com> wrote:
> Folks,
>
> Any suggestions on what's going on here?
>
> https://gist.github.com/876154
>
> The error is at the very bottom.
>
> This is code auto-generated by Apache Thrift.
>
>        Thanks, Joel
>
> --------------------------------------------------------------------------
> - for hire: mac osx device driver ninja, kernel extensions and usb drivers
> ---------------------+------------+---------------------------------------
> http://wagerlabs.com | @wagerlabs | http://www.linkedin.com/in/joelreymont
> ---------------------+------------+---------------------------------------
>
>
>
>
> --
> Caml-list mailing list.  Subscription management and archives:
> https://sympa-roc.inria.fr/wws/info/caml-list
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs
>
>

Re: [Caml-list] errors compiling thrift-generated code

[Joel Reymont]

> The easiest way to fix your problem is to change the interface so that:
> 
>    method copy : document
> 
> becomes:
> 
>    method copy : 'a

I changed copy in the mli but it doesn't seem to work.

Error: The implementation src/Hello_types.ml
       does not match the interface src/hello_types.cmi:
       Class declarations do not match:
         class document :
           object ('a)
             val mutable _docname : string option
             val mutable _page : int option
             val mutable _username : string option
             method copy : 'a
             method get_docname : string option
             method get_page : int option
             method get_username : string option
             method grab_docname : string
             method grab_page : int
             method grab_username : string
             method reset_docname : unit
             method reset_page : unit
             method reset_username : unit
             method set_docname : string -> unit
             method set_page : int -> unit
             method set_username : string -> unit
             method unset_docname : unit
             method unset_page : unit
             method unset_username : unit
             method write : Thrift.Protocol.t -> unit
           end
       does not match
         class document :
           object
             method copy : 'a
             method get_docname : string option
             method get_page : int option
             method get_username : string option
             method grab_docname : string
             method grab_page : int
             method grab_username : string
             method reset_docname : unit
             method reset_page : unit
             method reset_username : unit
             method set_docname : string -> unit
             method set_page : int -> unit
             method set_username : string -> unit
             method unset_docname : unit
             method unset_page : unit
             method unset_username : unit
             method write : Thrift.Protocol.t -> unit
           end
       The method copy has type
         < copy : 'a; get_docname : string option; get_page : int option;
           get_username : string option; grab_docname : string;
           grab_page : int; grab_username : string; reset_docname : unit;
           reset_page : unit; reset_username : unit;
           set_docname : string -> unit; set_page : int -> unit;
           set_username : string -> unit; unset_docname : unit;
           unset_page : unit; unset_username : unit;
           write : Thrift.Protocol.t -> unit; .. >
         as 'a
       but is expected to have type 'b. 'b
Command exited with code 2.


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Re: [Caml-list] errors compiling thrift-generated code

[Joel Reymont]

Niki,

On Mar 18, 2011, at 3:47 PM, Niki Yoshiuchi wrote:

> The easiest way to fix your problem is to change the interface so that:
> 
>   method copy : document
> 
> becomes:
> 
>   method copy : 'a

It appears that I also need object ('a) in the mli, e.g.

open Thrift
class document :
object ('a)
  ...
  method copy : 'a
  method write : Protocol.t -> unit
end

Thanks a lot for your help!

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Re: [Caml-list] errors compiling thrift-generated code

[Guillaume Yziquel]

Le Friday 18 Mar 2011 à 15:29:12 (+0100), Joel Reymont a écrit :
> Folks,
> 
> Any suggestions on what's going on here?
> 
> https://gist.github.com/876154
> 
> The error is at the very bottom.
> 
> This is code auto-generated by Apache Thrift.
> 
> 	Thanks, Joel

Can't say for sure, but I managed to have similar code compiling fine:

https://github.com/yziquel/OCaml-MPI/blob/master/datatype.p4.ml#L208
https://github.com/yziquel/OCaml-MPI/blob/master/datatype.p4.sig.mli#L45

I'd say: Try building class types first. But it's only a vague
impression I have when I try to recall how my code was built. Perhaps
changing the class in your .mli to have the method copy of type 'self?
The basic idea is that if you inherit from the class document, 'self
then denotes the derived class. That may be it. To my knowledge, there
isn't really a way to have classes as 'final' other than to use a
type my_class = private < some oo stuff here > construct, where you can
substitute 'self (which does not have any meaning in such a type
declaration) by my_class.

But it's all rather vague memories.

-- 
     Guillaume Yziquel

Re: [Caml-list] errors compiling thrift-generated code

[Joel Reymont]

On Mar 18, 2011, at 3:59 PM, Guillaume Yziquel wrote:

> Can't say for sure, but I managed to have similar code compiling fine:

Solved and filed a bug

https://issues.apache.org/jira/browse/THRIFT-1096

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