Proposal: reducing self.x=x; self.y=y; self.z=z boilerplate code

[Ron Adam]

Ralf W. Grosse-Kunstleve wrote:

>     class grouping:
> 
>         def __init__(self, .x, .y, .z):
>             # real code right here

The way this would work seems a bit inconsistent to me.  Args normally 
create local variables that receive references to the objects passed to 
them.

In this case, a function/method is *creating* non local names in a scope 
outside it's own name space to receive it's arguments.  I don't think 
that's a good idea.

A better approach is to have a copy_var_to(dest, *var_list) function 
that can do it.  You should be able to copy only selected arguments, and 
not all of them.

     copy_var_to(self,x,z)

Not exactly straight forward to do as it runs into the getting an 
objects name problem.


> Emulation using existing syntax::
> 
>         def __init__(self, x, y, z):
>             self.x = x
>             del x
>             self.y = y
>             del y
>             self.z = z
>             del z

The 'del's aren't needed as the references will be unbound as soon as 
__init__ is finished.  That's one of the reasons you need to do self.x=x 
, the other is to share the objects with other methods.



> Is there a way out with Python as-is?
> -------------------------------------

With argument lists that long it might be better to use a single 
dictionary to keep them in.

      class manager:
          def __init__(self, **args):
              defaults = {
              	'crystal_symmetry':None,
              	'model_indices':None,
              	'conformer_indices':None,
              	'site_symmetry_table':None,
              	'bond_params_table':None,
              	'shell_sym_tables':None,
              	'nonbonded_params':None,
              	'nonbonded_types':None,
              	'nonbonded_function':None,
              	'nonbonded_distance_cutoff':None,
              	'nonbonded_buffer':1,
              	'angle_proxies':None,
              	'dihedral_proxies':None,
              	'chirality_proxies':None,
              	'planarity_proxies':None,
              	'plain_pairs_radius':None }
              defaults.update(args)
              self.data = defaults
          	
              # real code

Regards,
	Ron