2.9. Summary

The apihelper.py program and its output should now make perfect sense.

Example 2.31. apihelper.py

def help(object, spacing=10, collapse=1):
    """Print methods and doc strings.
    Takes module, class, list, dictionary, or string."""
    methodList = [method for method in dir(object) if callable(getattr(object, method))]
    processFunc = collapse and (lambda s: " ".join(s.split())) or (lambda s: s)
    print "\n".join(["%s %s" %
                       processFunc(str(getattr(object, method).__doc__)))
                     for method in methodList])

if __name__ == "__main__":
    print help.__doc__

Example 2.32. Output of apihelper.py

>>> from apihelper import help
>>> li = []
>>> help(li)
append     L.append(object) -- append object to end
count      L.count(value) -> integer -- return number of occurrences of value
extend     L.extend(list) -- extend list by appending list elements
index      L.index(value) -> integer -- return index of first occurrence of value
insert     L.insert(index, object) -- insert object before index
pop        L.pop([index]) -> item -- remove and return item at index (default last)
remove     L.remove(value) -- remove first occurrence of value
reverse    L.reverse() -- reverse *IN PLACE*
sort       L.sort([cmpfunc]) -- sort *IN PLACE*; if given, cmpfunc(x, y) -> -1, 0, 1

Before diving into the next chapter, make sure you’re comfortable doing all of these things:

  • Defining and calling functions with optional and named arguments
  • Using str to coerce any arbitrary value into a string representation
  • Using getattr to get references to functions and other attributes dynamically
  • Extending the list comprehension syntax to do list filtering
  • Recognizing the and-or trick and using it safely
  • Defining lambda functions
  • Assigning functions to variables and calling the function by referencing the variable. I can’t emphasize this enough: this mode of thought is vital to advancing your understanding of Python. You’ll see more complex applications of this concept throughout this book.