Re: [Pytables-users] Way to derefer links?

[Maarten S. <maa...@xs...>]

On 18 dec 2009, at 11:43, Francesc Alted wrote:

> Hi List,
> 
> I'm about to merge the links branch into trunk, but suddenly it occurred to me 
> a new idea on how to dereferring soft/external links.  Currently, these links 
> work like this:
> 
> f = tb.openFile('links.h5', 'w')
> g = f.createGroup('/', 'g')
> a1 = f.createCArray(g, 'a', tb.Int64Atom(), shape=(10000,))
> la = f.createSoftLink('/', 'la', '/g/a')  # /la points to /g/a
> 
> and dereferring la is implemented via the `__call__()` method:
> 
> a2 = la()  # a2 is the 'a' CArray
> 
> But I think now that perhaps it would be better to implement dereferencing via 
> a property (say `target`):
> 
> a2 = la.target  # a2 is the 'a' CArray
> 
> That would allow to natural naming to work even through links referring to 
> groups.  For example, if lg
> 
> lg = f.createSoftLink('/', 'lg', '/g')  # /lg points to /g
> 
> then we could do:
> 
> a3 = f.root.lg.target.a  # a3 is the 'a' CArray
> 
> which I think is consistent with the way that PyTables uses to access nodes. 
> What people think?

Hi,

Do it in a way that doesn't require me to know if it is a link or not, group or otherwise. Of course when writing you will know, but not when using. I think that means I prefer the first method. 

In addition you can add a property to manipulate the link itself, but not for normal use of the data.

Best,

Maarten