dolfin team mailing list archive

[Johan Hake <hake@xxxxxxxxx>]

On Friday 08 May 2009 13:41:37 Ola Skavhaug wrote:
> On Fri, May 8, 2009 at 11:40 AM, Anders Logg <logg@xxxxxxxxx> wrote:
> > On Fri, May 08, 2009 at 11:19:35AM +0200, Anders Logg wrote:
> >> We currently have two ways to print object data to the screen in
> >> DOLFIN:
> >>
> >>   cout << foo << endl;
> >>
> >>   foo.disp()
> >>
> >> The first of these prints a nicely-formatted one-liner:
> >>
> >>   [Mesh of topological dimension 2 with 121 vertices and 200 cells]
> >>
> >> The second prints more detailed information:
> >>
> >> Mesh data
> >> ---------
> >>
> >>   Mesh topology
> >>   -------------
> >>
> >>     Topological dimension: 2
> >>
> >>     Number of entities:
> >>
> >>       dim = 0: 121
> >>       dim = 1: 0
> >>       dim = 2: 200
> >>
> >>     ...
> >>
> >>     Connectivity:
> >>
> >>         0 1 2
> >>       0 - - -
> >>       1 - - -
> >>       2 x - -
> >>
> >>     Connectivity 2 -- 0:
> >>
> >>       0: 0 1 12
> >>       1: 0 11 12
> >>       2: 1 2 13
> >>       3: 1 12 13
> >>
> >> I'm thinking we could add a method named str() to all classes and then
> >> call str() both from LogStream<< and from __str__ in Python.
> >>
> >> Should the disp() method remain as it is today or should it be renamed
> >> to something else? Maybe print()?
> >
> > Or maybe info() is more logical, since calling foo.info() will result
> > in a string being sent to the info() function.

This won't work for some of the linear algebra disp's as these rely on the 
underlaying library. We can of course change this.

> I like this idea. Will all dolfin classes inherit a pure virtual base
> class defining the str() method?

Isn't the meaning of str() to return a string representation of the object? 
Not print it. That should Info, Debug and its like do?

With disp it is another case as I expect this function to print to the screen 
if I do not tell it otherwise.

Also _pure_ virtual is good. Haveing a base class that all classes should 
inherit is not good as the public/protected base class methods are 
unreachable for the derived classes when these are declared as shared_ptr 
classes in swig. 

> If that's the case, we can, optionally, provide a stream to which the
> info is written, e.g., cerr, cout, or a stringstream from Python.

Could this be done by

  info(foo.str());

and then redirect the output of info?

Johan
> Ola
>
> > --
> > Anders
> >
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