How can I type-check variables in Python?

Question

I have a Python function that takes a numeric argument that must be an integer in order for it behave correctly. What is the preferred way of verifying this

Answer 1

Programming in Python and performing typechecking as you might in other languages does seem like choosing a screwdriver to bang a nail in with. It is more elegant to use Python's exception handling features.

From an interactive command line, you can run a statement like:

int('sometext')

That will generate an error - ipython tells me:

: invalid literal for int() with base 10: 'sometext'

Now you can write some code like:

try:
   int(myvar) + 50
except ValueError:
   print "Not a number"

That can be customised to perform whatever operations are required AND to catch any errors that are expected. It looks a bit convoluted but fits the syntax and idioms of Python and results in very readable code (once you become used to speaking Python).