How to extend an object?

[DL Neil]

On 21/12/19 2:50 pm, Greg Ewing wrote:
> On 21/12/19 1:59 am, Stefan Ram wrote:
>>    I would like to add a method to a string.
>>
>>    This is not possible in Python?
> 
> It's not possible. Built-in classes can't have methods added
> to them.
> 
> You can define your own subclass of str and give it whatever
> methods you want.
> 
> But in your case:
> 
>> for s in 'abc'.like( '(.)' ):
> 
> I would recommend making it a stand-alone function instead,
> so that you would write
> 
>    for s in like('abc', '(.)'):


Contrarily: sub-classing str and making like() a method strikes me as 
the way to go, particularly if the 'abc' disappears into the instance's 
__init__() - and better still if the '(.)' may also be absorbed as a 
class/instance attribute, and even more-so if like() is not the only 
method/stand-alone function required for this category of strings...

but...

choose a self-documenting name for the class, and
choose a better-documenting name for the method.

instance = class( "abc" )
...
for s in instance.method():

is clean, self-documenting (or will be once you've done your thing), 
easier to test (fewer args => easier assured testing).

-- 
Regards =dn