diff --git a/porting-code-to-python-3-with-2to3.html b/porting-code-to-python-3-with-2to3.html index 166be8c..37b05c8 100644 --- a/porting-code-to-python-3-with-2to3.html +++ b/porting-code-to-python-3-with-2to3.html @@ -31,9 +31,11 @@ td pre{padding:0;border:0}

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Diving in

Virtually all Python 2 programs will need at least some tweaking to run properly under Python 3. To help with this transition, Python 3 comes with a utility script called 2to3, which takes your actual Python 2 source code as input and auto-converts as much as it can to Python 3. Case study: porting chardet to Python 3 describes how to run the 2to3 script, then shows some things it can’t fix automatically. This appendix documents what it can fix automatically. +

print statement

In Python 2, print was a statement. Whatever you wanted to print simply followed the print keyword. In Python 3, print() is a function — whatever you want to print is passed to print() like any other function. @@ -515,6 +517,7 @@ for an_iterator in a_sequence_of_iterators:

FIXME +

map() global function

In much the same way as filter(), the map() function now returns an iterator. (In Python 2, it returned a list.) @@ -897,6 +900,7 @@ except:

☃ +

lambda functions that take a tuple instead of multiple parameters

In Python 2, you could define anonymous lambda functions which took multiple parameters by defining the function as taking a tuple with a specific number of items. In effect, Python 2 would “unpack” the tuple into named arguments, which you could then reference (by name) within the lambda function. In Python 3, you can still pass a tuple to a lambda function, but the Python interpreter will not unpack the tuple into named arguments. Instead, you will need to reference each argument by its positional index.