[Octave-bug-tracker] [bug #58780] 'source' throws unexpected syntax error.

[John W. Eaton]

Update of bug #58780 (project octave):

                  Status:               Confirmed => Need Info              

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Follow-up Comment #5:

The attached change appears to help, but something strange still happens when
sourcing files that are functions instead of scripts.

With the change, I see the following:


>> source foo  ## Does not automatically append .m
error: source: error sourcing file '/tmp/foo': no such file, '/tmp/foo'
>> source foo.m  ## Improved error reporting:
error: source: error sourcing file '/tmp/foo.m': parse error near line 1 of
file /tmp/foo.m

  syntax error

>>> (1))
        ^
>> source foo.m  ## Syntax error fixed; code executed
ans = 1
>> type foo.m  ## Make it a simple function instead:
foo.m is the user-defined function defined from: /tmp/foo.m

function foo ()
  'this is FOO!!'
end

>> source foo.m  ## Source works, but function not executed
>> foo           ## Is it defined?  Yes.
ans = this is FOO!!
>> which foo     ## Hmm, this seems wrong.
'foo' is a command-line function


So it seems that when we parse the file, it is being entered into  Octave's
table of known functions.  But I'm not sure that's the best thing to do.

Note that the existing code has the comment


// For compatibility with Matlab, accept both scripts and functions.


but I don't think Matlab has the "source" function.  So I assume this comment
was added because Octave's "run" function (which Matlab does have) calls
"source", and Matlab's "run" function will execute functions that have no
arguments.

I'm curious to know whether Matlab's "run" function parses the file every
time, or whether it caches the result.  We should be able to test as follows. 
Create a file foo.m with the contents


function foo ()
  persistent val
  if (isempty (val))
    val = 1
  else
     val = val + 1
  end
end


then execute


run foo.m
run foo.m


Does it print val = 1 each time, or is val incremented or is there some
error?


(file #49704)
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Additional Item Attachment:

File name: source-diffs.txt               Size:2 KB
    <https://file.savannah.gnu.org/file/source-diffs.txt?file_id=49704>



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