Function evaluate_expression

_pydevd_bundle/pydevd_vars.py:445–598

:param str expression: The expression to be evaluated. Note that if the expression is indented it's automatically dedented (based on the indentation found on the first non-empty line). i.e.: something as: ` def method(): a =

(py_db, frame, expression, is_exec)

@_evaluate_with_timeouts
def evaluate_expression(py_db, frame, expression, is_exec):
    """
    :param str expression:
        The expression to be evaluated.

        Note that if the expression is indented it's automatically dedented (based on the indentation
        found on the first non-empty line).

        i.e.: something as:

        `
            def method():
                a = 1
        `

        becomes:

        `
        def method():
            a = 1
        `

        Also, it's possible to evaluate calls with a top-level await (currently this is done by
        creating a new event loop in a new thread and making the evaluate at that thread -- note
        that this is still done synchronously so the evaluation has to finish before this
        function returns).

    :param is_exec: determines if we should do an exec or an eval.
        There are some changes in this function depending on whether it's an exec or an eval.

        When it's an exec (i.e.: is_exec==True):
            This function returns None.
            Any exception that happens during the evaluation is reraised.
            If the expression could actually be evaluated, the variable is printed to the console if not None.

        When it's an eval (i.e.: is_exec==False):
            This function returns the result from the evaluation.
            If some exception happens in this case, the exception is caught and a ExceptionOnEvaluate is returned.
            Also, in this case we try to resolve name-mangling (i.e.: to be able to add a self.__my_var watch).

    :param py_db:
        The debugger. Only needed if some top-level await is detected (for creating a
        PyDBDaemonThread).
    """
    if frame is None:
        return

    # This is very tricky. Some statements can change locals and use them in the same
    # call (see https://github.com/microsoft/debugpy/issues/815), also, if locals and globals are
    # passed separately, it's possible that one gets updated but apparently Python will still
    # try to load from the other, so, what's done is that we merge all in a single dict and
    # then go on and update the frame with the results afterwards.

    # -- see tests in test_evaluate_expression.py

    # This doesn't work because the variables aren't updated in the locals in case the
    # evaluation tries to set a variable and use it in the same expression.
    # updated_globals = frame.f_globals