On 7/18/2012 10:40 AM, Lipska the Kat wrote:
fact ... and I have never been forced to admit that I don't know what I
wrote six months ago.
That is an explicit objective of Python's design.
Python looks like an interesting language and I will certainly spend
time getting to know it but at the moment it seems to me that calling it
an Object Oriented language is just plain misleading.
I just call it object-based and let be done with it, as I have no
interest in arguing 'Object Oriented'.
What perhaps *you* need to know, given your background, is that nearly
all syntax and most builtin callables wrap special method calls that can
be defined on user classes.
'a + b' is executed as something like
try:
return a.__add__(b) # or the C type slot equivalent
except: # not sure what is actually caught
try:
return b.__radd__(a) # r(everse)add
except: # ditto
raise TypeError("unsupported operand type(s) for +: {} and
{}".format(a, b))
[Syntax exceptions: =, and, or]
'len(x)' calls x.__len__ and checks that the return value can be
interpreted as an integer (I believe that means that it is an int or has
an __index__ method, so that it can be used as a sequence index) and
that its value is >= 0.
--
Terry Jan Reedy
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