Comment author: administrator

Full_Name: Pascal Zimmer
Version: 3.07
OS: Linux
Submission from: vishnu.inria.fr (138.96.82.1)

In one of my project, I needed to empty the lexing buffer when I encountered an
error in an interactive session (in exactly the same way as OCaml does: stop
interpreting the remaining phrases when there is an error, discard what remains
and wait for new phrases).
After a few searches, I copied the empty_lexbuf function from the file
toploop.ml and it worked perfectly (this was with OCaml 3.04). I just noticed
this function didn't work anymore since 3.05... After checking, the function in
toploop.ml had been modified, and it has changed once more in 3.07beta1 !

Would it be possible to include empty_lexbuf directly in the module Lexing, so
that we do not have to bother with those modifications ? This function seems
quite useful to me in such situations.

Thanks.

Hello, We can indeed move empty_lexbuf from toploop.ml to
lexing.ml. However this function looks very top level oriented and
seems to make sense only when the input channel is an interactive one.
Advice ?

--Luc

Comment author: administrator

Hello,

Would it be possible to include empty_lexbuf directly in the module Lexing,
so
that we do not have to bother with those modifications ? This function seems
quite useful to me in such situations.

I have implemented your suggestion, but I renamed the function to
Lexing.flush_input, a name that I find more descriptive.

-- Damien

Comment author: administrator

Full_Name: Pascal Zimmer
Version: 3.07
OS: Linux
Submission from: vishnu.inria.fr (138.96.82.1)

In one of my project, I needed to empty the lexing buffer when I encountered an
error in an interactive session (in exactly the same way as OCaml does: stop
interpreting the remaining phrases when there is an error, discard what remains
and wait for new phrases).
After a few searches, I copied the empty_lexbuf function from the file
toploop.ml and it worked perfectly (this was with OCaml 3.04). I just noticed
this function didn't work anymore since 3.05... After checking, the function in
toploop.ml had been modified, and it has changed once more in 3.07beta1 !

Would it be possible to include empty_lexbuf directly in the module Lexing, so
that we do not have to bother with those modifications ? This function seems
quite useful to me in such situations.

Thanks.

Luc Maranget wrote:

Hello, We can indeed move empty_lexbuf from toploop.ml to
lexing.ml. However this function looks very top level oriented and
seems to make sense only when the input channel is an interactive one.
Advice ?

I agree. My point was that:

• when you program an interactive intrepreter in OCaml, you will need
  such a function, and since the type Lexing.lexbuf is not fully
  documented, it is really not obvious to write it down without looking
  either at the implementation of Lexing or at another programmer's work,
  like in toploop.ml
• the implementation of lexbuf has changed three times during the last
  releases; in every case the function would not work anymore, and you
  would have to first find the bug, and secondly remind to look into
  toploop.ml and update the function. This is why I prefer a
  library-provided version.

Damien Doligez wrote:

I have implemented your suggestion, but I renamed the function to
Lexing.flush_input, a name that I find more descriptive.

Fine. Thanks !

Pascal

Comment author: administrator

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