Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From: Dan Strohl <D.Strohl@F5.com>
Newsgroups: comp.lang.python
Subject: RE: Need help understanding list structure
Date: Tue, 3 May 2016 17:54:38 +0000
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Xref: csiph.com comp.lang.python:108090


> I added a __repr__ method at the end of the gedcom library like so:
>=20
> def __repr__(self):
>         """ Format this element as its original string """
>         result =3D repr(self.level())
>         if self.pointer() !=3D "":
>             result +=3D ' ' + self.pointer()
>         result +=3D ' ' + self.tag()
>         if self.value() !=3D "":
>             result +=3D ' ' + self.value()
>         return result
>=20
> and now I can print myList properly.
>=20
> Eric and Michael also mentioned repr above, but I guess I needed someone
> to spell it out for me. Thanks for taking the time to put it in terms an =
old dog
> could understand.
>=20

Glad to help!  (being an old dog myself, I know the feeling!)

One other point for you, if your "__repr__(self)" code is the same as the "=
__str__(self)" code (which it looks like it is, at a glance at least), you =
can instead reference the __str__ method and save having a duplicate code b=
lock...  some examples:

=3D=3D=3D=3D=3D=3D=3D=3D=3D
Option 1:  This is the easiest to read (IMHO) and allows for the possibilit=
y that str() is doing something here like formatting or whatever.  (in this=
 case it shouldn't be though).  However, to call this actually is taking mu=
ltiple steps (calling object.__repr__, whch calls str(), which calls object=
.__str__(). )

def __repr__(self):
    return str(self)

=3D=3D=3D=3D=3D=3D=3D=3D=3D
Option 2: this isn't hard to read, and just takes two steps (calling object=
.__repr__(), which calls object.__str__().

def __repr__(self):
    return self.__str__()

=3D=3D=3D=3D=3D=3D=3D=3D
Option 3:  it's not that this is hard to read, but since it doesn't follow =
the standard "def blah(self):" pattern, sometimes I overlook these in the c=
ode (even when I put them there).  This however is the shortest since it re=
ally just tells the object to return object.__str__() if either object.__re=
pr__() OR object.__str__() is called.


__repr__ =3D __str__


This probably doesn't matter much in this case, since it probably isn't cal=
led that much in normal use (though there are always exceptions), and in th=
e end, Python is fast enough that unless you really need to slice off a few=
 milliseconds, you will never notice the difference, but just some food for=
 thought.