Product Documentation

ActivePython 2.5 Documentation

4 Using Backslash to Continue Statements

Since Python treats a newline as a statement terminator, and since statements are often more then is comfortable to put in one line, many people do:

if foo.bar()['first'][0] == baz.quux(1, 2)[5:9] and \
   calculate_number(10, 20) != forbulate(500, 360):
      pass

You should realize that this is dangerous: a stray space after the would make this line wrong, and stray spaces are notoriously hard to see in editors. In this case, at least it would be a syntax error, but if the code was:

value = foo.bar()['first'][0]*baz.quux(1, 2)[5:9] \
        + calculate_number(10, 20)*forbulate(500, 360)

then it would just be subtly wrong.

It is usually much better to use the implicit continuation inside parenthesis:

This version is bulletproof:

value = (foo.bar()['first'][0]*baz.quux(1, 2)[5:9] 
        + calculate_number(10, 20)*forbulate(500, 360))