AutoComplete in C++ Editor for Python

[flamz3d at gmail.com]

On May 3, 3:14 pm, Dave Angel <da... at ieee.org> wrote:
> flam... at gmail.com wrote:
> > Hello,
> > I am embedding python support in my C++ application and was looking at
> > adding "Intellisense" or "AutoComplete" support.
>
> > I found a way to do it using the "dir" function, but this creates a
> > problem. Here's why. Let's say I have the following code in my editor:
>
> > import sys
> > x = sys
>
> > Now, I would like to get all attributes of the object called 'x'. I
> > can "instrument" the code and add "print dir(x)" at the end,
> > temporarily redirect the python output to a string and execute the
> > code.
>
> > But this is not safe: I do NOT want to execute the code while the user
> > is typing!
>
> > Is there a way to "compile" the python code and get access to the
> > symbol table from that compiled block?
>
> > Did anybody ever implement AutoComplete in a editor for Python?
>
> > cheers.
>
> Several editors for Python support auto-complete, to one extent or
> another.  The only one I have experience with is Komodo.  Komodo runs in
> a separate process, so it doesn't suffer from the problems of having two
> gui event-loops in the same process, and other similar problems.   It
> also won't be executing code that might have side effects in the child
> process.
>
> The downside is that in order to do auto-complete, it has to figure it
> out from other clues.  From the docs, and from reading, and from
> experiementing, I believe that it uses two approaches.  One approach is
> a set of language files which try to describe all the symbols in the
> standard language and library.  They have one for each release (2.4,
> 2.5, ...)  Theoretically, you could add your own for other libraries.  
> Second approach is to parse the code that's visible to it.  That parsing
> is well done, and surprisingly quick, but there are lots of tricks a
> developer might use that can fool it.  For example, wxPython lets you
> import just one symbol, and lots more appear magically.  It's no big
> deal, they have code structured one way, but the interface is very
> different.  Catch is that code completion frequently gets fooled by these.
>
> I'd point out that if you do walk the dictionaries at run time, you'll
> get different results when you do it with nothing running than if you do
> a strictly static analysis.  So some things might only show up if you've
> stepped into the function with the magic going on.
>
> Simplest example I can come up with of something a static analysis won't
> spot:   An instance object    obj   may have some number of attributes
> assigned the the __init__() method.  But it could also have new fields
> added by anyone with a referent into it.
>
> There is a Python parser in module ast.  Perhaps that'd be some help.  
> I've not used it, so can't give you any specifics.
>
> DaveA


I think it might be possible for me to figure out how to do
AutoCompletion using the symtable object. But I am having difficulty
making sense of it.

In my tests, I was use the following Python code:

[code]
import sys
x=sys
[/code]

The idea is to get the type of the variable x

To attempt this, I use the following C code (my editor is written in
C)

symtable* st = Py_SymtableString ( "import sys
\nx=sys,"<string>",Py_single_input);

PyObject *name, *value;
Py_ssize_t pos = 0;
while (PyDict_Next(st->st_symbols, &pos, &name, &value))
{
...
}



Using this code, I can get information like the name of the symbol
(x), but I can't figure out how to get the type. If I knew how to get
this it would solve 99% of my problems :)

Any ideas?