Equivalent of python walrus operator (:=) in c++11?

Recently I have been using the := operator in python quite a bit, in this way:

if my_object := SomeClass.function_that_returns_object():
    # do something with this object if it exists
    print(my_object.some_attribute)

The question

Is there any way to do this in c++11 without the use of stdlib? for example in an arduino sketch if I wanted to use a method that may potentially return zero, such as:

if(char * data = myFile.readBytes(data, dataLen))
{
    // do something
}
else
{
    // do something else
}