[cfe-commits] [PATCH 4/4] [clang.py] TranslationUnit API improvements

[Gregory Szorc]

Here is a revamped patch. I think we'll all be much happier with it.

Strangely, the unit test for TranslationUnit.save() on an invalid TU
is now failing because clang_saveTranslationUnit() is no longer
returning a non-0 error. I'm not sure if it is an error in the Python
bindings, the test, or a change in behavior in libclang (possibly
r153560 or r152192). Whatever it is should be resolved before this
lands.

On Sun, Apr 15, 2012 at 1:27 PM, Gregory Szorc <gregory.szorc at gmail.com> wrote:
> On Fri, Apr 13, 2012 at 3:38 AM, Manuel Klimek <klimek at google.com> wrote:
>> What's ERROR_OK needed for? It looks like it's not currently used; it
>> actually looks like it's impossible to ever raise an exception with
>> it...
>
> That's true. I added it for parity with the C API. It can safely be removed.
>
>> +    def __init__(self, ptr=None, filename=None, index=None):
>> +        """Create a TranslationUnit instance.
>> +
>> +        Instances can be created in the following ways:
>> +
>> +          * By passing a pointer to a c_object_p instance via ptr. This is
>> +            an internal mechanism and should not be used outside of this
>> +            module.
>>
>> This interface seems strange - why have the mixture of 2 constructors in one?
>
> Why not?
>
> Unfortunately, I can't find any reputable style guidelines to defend
> either perspective. The closest I have is
> http://stackoverflow.com/questions/682504/what-is-a-clean-pythonic-way-to-have-multiple-constructors-in-python.
> And, that seems to indicate a mix of an "overloaded" __init__ with
> @classmethod is preferred. But, that's just one SO question.
>
> Is this particular case, a TranslationUnit is ultimately instantiated
> from a c_object_p "ptr." If we limited __init__ to a single
> instantiation mode, we'd have to pass a c_object_p and since these are
> internal to the module, __init__ wouldn't be an external API. In other
> words, we'd be throwing __init__ away. Since Python programmers look
> to __init__ first, I think this would be inconvenient. From an
> external perspective, TranslationUnit still only has 1 instantiation
> mode. If it had more, I'd definitely favor adding @classmethods to
> cover each. I'm not against it today: I just see no reason for it.
>
> Anyway, as I typed this, I realized that we need an additional
> constructor mode: from source file (e.g. Index.parse). Let me code up
> a new patch and we'll see what you think.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-clang.py-TranslationUnit-API-improvements.patch
Type: application/octet-stream
Size: 26053 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20120415/75fcf286/attachment.obj>