[Tutor] raising exceptions in constructor code?

[Alan Gauld]

On 16/07/2019 22:56, Mats Wichmann wrote:

>> thrown.  This gets watered down to the mantra "Don't throw exceptions from
>> within constructors."  Does this carry over to Python?  

> 
> If you mean __init__, that's not a constructor, so you should set your
> mind at rest :)   It's more properly an "initializer", the instance has
> already been constructed when it's called.

FWIW The true constructor is __new__() and its quite rarely overridden
by application programmers. But if you do, it's not common that you'd do
anything that would merit an exception. __new__ pretty much just sets
up the structure of the object ready for initialisation by __init__.

Incidentally, this two stage construction/initialisation is also found
in other OOP languages like Smalltalk and Objective C (and Lisp?).

-- 
Alan G
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