dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Fri, May 08, 2009 at 01:53:36PM +0200, Johan Hake wrote:
> 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?

Maybe we can have repr() for that, but I imagine it's hard to do that
for a Mesh or a Matrix.

There seem to be three different ways one may want to get a string
from an object:

  repr(): full information such that the object can be recreated from
          the string (foo = Foo(foo.__repr__()))

  str():  a short one-liner

  info(): more detailed information spanning over several lines

-- 
Anders


> 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
> >
> > >
> > > -----BEGIN PGP SIGNATURE-----
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> > >
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> > > sPgAn1399kkwXnp7jyp2R9cTarJn0vUZ
> > > =qi/J
> > > -----END PGP SIGNATURE-----
> > >
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> 
> 
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