jeff at ccvcorp.com
Thu Jul 8 02:09:33 CEST 2004
bruce stockwell wrote:
>Using 'self' in classes seems pretty straight forward. My curiosity is
>why I have to use it. Shouldn't it be implied?
The problem is that an implied 'self' is harder to read than an explicit
'self', and also opens the door for ambiguity when an instance attribute
has the same name as a global or builtin attribute.
Let's look at an example in a hypothetical Python variant where 'self'
is implied --
# do stuff here
# do stuff here
e = eye()
But wait -- open() is an obsolete built-in function for opening a file.
Which should eye.blink() do -- open and close the right eye, or open a
file with the name of 'right' ?? If it's the former, then what do you
do if you *want* to open that file? If it's the latter, then what
happens when the next version of Python comes along and open() has been
removed from built-ins?
Even without these namespace conflicts, it's difficult when you're
reading a long method and see a call to "make_thingumbob()" -- where do
you look to see what that does? It might be another method of that
class, or it might be a global (or even built-in) function. It then
requires extra thought and search-time to figure out the intent.
One of the design principles of Python is that ease of *reading* is more
important than ease of *writing*. It's worth a few extra keystrokes if
it will save you a second or two of time when reading unfamiliar code --
because most code is only written once, but read *many* times.
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