Don't automatically copy python objects into javascript

[hoodmane]

This implements (the most important change suggested in) #900. This should also make the custom globals / locals feature of eval_code implemented in #1106 work significantly better.

[phorward]

Hello @hoodmane, thanks for the Pull Request. From the code base this looks fine to me. Can you please shortly explain the changes in the test suite?

[dalcde]

Since selenium.run uses runPython under the hood, wouldn't the semicolon itself suffice?

[hoodmane]

Yeah it would work, I opted for ; pass because I think that is a little more conspicuous.

[phorward]

@hoodmane: It seems that we now have a regression with test_console.py and your change, can you please take a look at it? I don't know how to fix it quickly.

___________________________ test_completion[firefox] ___________________________
[gw2] linux -- Python 3.8.2 /usr/local/bin/python

selenium = <conftest.FirefoxWrapper object at 0x7f6529803a00>
safe_selenium_sys_redirections = None

    def test_completion(selenium, safe_selenium_sys_redirections):
        selenium.run(
            """
        from pyodide import console
    
        shell = console.InteractiveConsole()
        """
        )
    
>       assert selenium.run("shell.complete('a')") == [
            [
                "and ",
                "as ",
                "assert ",
                "async ",
                "await ",
                "abs(",
                "all(",
                "any(",
                "ascii(",
            ],
            0,
        ]
E       AssertionError: assert [None, 0] == [['and ', 'as...bs(', ...], 0]
E         At index 0 diff: None != ['and ', 'as ', 'assert ', 'async ', 'await ', 'abs(', 'all(', 'any(', 'ascii(']
E         Full diff:
E           [
E         +  None,
E         -  ['and ',
E         -   'as ',
E         -   'assert ',
E         -   'async ',
E         -   'await ',
E         -   'abs(',
E         -   'all(',
E         -   'any(',
E         -   'ascii('],
E            0,
E           ]

src/tests/test_console.py:201: AssertionError

Next time it would be better to first merge master into this branch, and re-test it first.

[phorward]

@hoodmane can you please investigate? I think the problem is in the conversion of Tuples, which is the case here.

pyodide.runPython("from pyodide import console; shell = console.InteractiveConsole(); shell.complete('a')")

returns Array [ Proxy, 0 ], which seems to be invalid, as it should be Array [ Array ['and ', 'as ', 'assert ', 'async ', 'await ', 'abs(', 'all(', 'any(', 'ascii('], 0 ].

[phorward]

@hoodmane I'm sorry I reverted your Pull Request because after a 3 hour examination of the problem I wasn't able to get into a solution. Maybe you should take a look on it. Can you then please re-open the Pull Request again, as I don't have a possibility to do it here.

[hoodmane]

This PR currently is a bit bad for usability, it needs some supporting changes to pyproxy to make it a bit easier to use. I was thinking the right approach would be to merge this as-is and then preferably fix the ergonomics problems before the next release, but I could see adding more to this PR.
The tests can be fixed by turning:

        shell.complete('a = 0 ; print.__g')

into

        [completions, start] = shell.complete('a = 0 ; print.__g')
        [tuple(completions), start]

[hoodmane]

Oh also the docs on type conversions and the changelog should be updated.

[hoodmane]

Presumably implementing toJSON on pyproxy would make the tests pass more painlessly.