I know how to override string class with:
class UserString:
def __str__(self):
return 'Overridden String'
if __name__ == '__main__':
print UserString()
But how can i use this class instead of built-in str class without defining implicitly UserString class?. To be clear
I want this:
>>> print "Boo boo!"
Overridden String
It is not possible. You have not overridden string class.
You cannot override classes. You can override methods. What you have done is defined a class and only overridden its str() method.
But you can do something like this...
def overriden_print(x):
print "Overriden in the past!"
from __future__ import print_function # import after the definition of overriden_print
print = overriden_print
print("Hello")
Output:
Overriden in the past!
It's impossible to do what you want without hacking the python executable itself... after all, str is a built-in type, and the interpreter, when passed 'string' type immediates, will always create built-in strings.
However... it is possible, using delegation, to do something like this. This is slightly modified from another stackoverflow recipe (which sadly, I did not include a link to in my code...), so if this is your code, please feel free to claim it :)
def returnthisclassfrom(specials):
specialnames = ['__%s__' % s for s in specials.split()]
def wrapit(cls, method):
return lambda *a: cls(method(*a))
def dowrap(cls):
for n in specialnames:
method = getattr(cls, n)
setattr(cls, n, wrapit(cls, method))
return cls
return dowrap
Then you use it like this:
@returnthisclassfrom('add mul mod')
class UserString(str):
pass
In [11]: first = UserString('first')
In [12]: print first
first
In [13]: type(first)
Out[13]: __main__.UserString
In [14]: second = first + 'second'
In [15]: print second
firstsecond
In [16]: type(second)
Out[16]: __main__.UserString
One downside of this is that str has no radd support, so 'string1' + UserString('string2') will give a string, whereas UserString('string1') + 'string2' gives a UserString. Not sure if there is a way around that.
Maybe not helpful, but hopefully it puts you on the right track.
print?MYSTRING.upper()method triggerer, I want to trigger my ownupper()method.