diff --git a/porting-code-to-python-3-with-2to3.html b/porting-code-to-python-3-with-2to3.html index 3641b35..0a33ddd 100644 --- a/porting-code-to-python-3-with-2to3.html +++ b/porting-code-to-python-3-with-2to3.html @@ -549,7 +549,7 @@ for an_iterator in a_sequence_of_iterators:
  • Again, no changes are necessary, because the list comprehension will iterate through the entire sequence, and it can do that just as well if map() returns an iterator as if it returns a list. -

    reduce() global function (3.1+)

    +

    reduce() global function

    In Python 3, the reduce() function has been removed from the global namespace and placed in the functools module. @@ -563,10 +563,6 @@ for an_iterator in a_sequence_of_iterators: reduce(a, b, c) -

    -

    ☞The version of 2to3 that shipped with Python 3.0 would not fix the reduce() function automatically. The fix first appeared in the 2to3 script that shipped with Python 3.1. -

    -

    apply() global function

    Python 2 had a global function called apply(), which took a function f and a list [a, b, c] and returned f(a, b, c). You can accomplish the same thing by calling the function directly and passing it the list of arguments preceded by an asterisk. In Python 3, the apply() function no longer exists; you must use the asterisk notation. @@ -634,7 +630,7 @@ reduce(a, b, c)

  • Even fancier, the old exec statement could also take a local namespace (like the variables defined within a function). In Python 3, the exec() function can do that too. -

    execfile statement (3.1+)

    +

    execfile statement

    Like the old exec statement, the old execfile statement will execute strings as if they were Python code. Where exec took a string, execfile took a filename. In Python 3, the execfile statement has been eliminated. If you really need to take a file of Python code and execute it (but you’re not willing to simply import it), you can accomplish the same thing by opening the file, reading its contents, calling the global compile() function to force the Python interpreter to compile the code, and then call the new exec() function. @@ -647,10 +643,6 @@ reduce(a, b, c) exec(compile(open('a_filename').read(), 'a_filename', 'exec')) -

    -

    ☞The version of 2to3 that shipped with Python 3.0 would not fix the execfile statement automatically. The fix first appeared in the 2to3 script that shipped with Python 3.1. -

    -

    repr literals (backticks)

    In Python 2, there was a special syntax of wrapping any object in backticks (like `x`) to get a representation of the object. In Python 3, this capability still exists, but you can no longer use backticks to get it. Instead, use the global repr() function. @@ -1131,7 +1123,7 @@ except:

    ☞types.StringType gets mapped to bytes instead of str because a Python 2 “string” (not a Unicode string, just a regular string) is really just a sequence of bytes in a particular character encoding. -

    isinstance() global function (3.1+)

    +

    isinstance() global function

    The isinstance() function checks whether an object is an instance of a particular class or type. In Python 2, you could pass a tuple of types, and isinstance() would return True if the object was any of those types. In Python 3, you can still do this, but passing the same type twice is deprecated. @@ -1144,10 +1136,6 @@ except: isinstance(x, (int, float)) -

    -

    ☞The version of 2to3 that shipped with Python 3.0 would not fix these cases of isinstance() automatically. The fix first appeared in the 2to3 script that shipped with Python 3.1. -

    -

    basestring datatype

    Python 2 had two string types: Unicode and non-Unicode. But there was also another type, basestring. It was an abstract type, a superclass for both the str and unicode types. It couldn’t be called or instantiated directly, but you could pass it to the global isinstance() function to check whether an object was either a Unicode or non-Unicode string. In Python 3, there is only one string type, so basestring has no reason to exist.