[Python-ideas] Make compile('1\n2\n', '', 'single') raise an exception instead of silently truncating?

Devin Jeanpierre jeanpierreda at gmail.com
Sun Aug 7 02:25:43 CEST 2011

Hi, I really would like some feedback on this. Or should I send it to
the bug tracker? Was this the wrong place?


On Wed, Jul 20, 2011 at 10:47 AM, Devin Jeanpierre
<jeanpierreda at gmail.com> wrote:
> compile('1\n2\n', '','single') == compile('1\n', '','single').
> That is, it ignores the second statement ('2\n'),
> without offering a way for the caller to detect this.
> Considering that 'single' is primarily used to emulate the behaviour
> of the Python interpreter, most of the time, giving it multiple
> statements is an impossibility, and so that case doesn't matter and
> could raise an exception without affecting existing code. For example,
> the code module meets this description, as do debuggers and such.
> However, in cases where it _is_ possible to give the compiler multiple
> statements, the user should be warned that his input isn't valid,
> somehow. For example, the following doctest will mysteriously fail,
> because it was written incorrectly (doctest uses 'single'):
>    >>> import sys
>    ... sys.stdout.write('foo\n')
>    foo
> This is because the second statement in the doctest was silently
> discarded by compile(). It might not always be clear to users how to
> fix this, and I think this kind of non-obvious error would exist in
> any use of 'single' that can in theory involve multiple statements,
> through user error or program bug. So I'd appreciate it if compile()
> raised an exception in this case. Perhaps SyntaxError or ValueError.
> Devin

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