[Octave-bug-tracker] [bug #45835] wrong scope may be used in anonymous function evaluation

[John W. Eaton]

Update of bug #45835 (project octave):

                 Summary: interpreter does not search for anonymous function
variables within a string => wrong scope may be used in anonymous function
evaluation

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Follow-up Comment #5:

I'm retitling this report.

Note the difference in the following:


f = @() __current_scope__
g = @() eval ('__current_scope__')
f()
g()


The trouble is caused by this function:

http://hg.savannah.gnu.org/hgweb/octave/annotate/2f94652de9ff/libinterp/octave-value/ov-fcn-handle.cc#l1945

I believe the purpose of the octave_fcn_binder object is to optimize things
like


@f(x) sin (x)


so that they are almost as efficient as calling the internal function directly
instead of going through all the effort of evaluating a user-defined function
simply to call another function or simple expression.

You can show that the problem disappears if you make the body of the
octave_fcn_binder::maybe_binder function be


  return new octave_fcn_handle (f, octave_fcn_handle::anonymous);


I'm looking to see whether there is a simple fix that will preserve this
optimization and make the eval case work properly.

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