[Tutor] Type Checking:/High-Jacking Reserved Words

[D-Man]

On Sun, Mar 04, 2001 at 08:16:06AM -0900, Tim Johnson wrote:
| I would welcome some comments from anyone as to the
| comparative advantages of the following
| >     type(mystr) == types.StringType
| as opposed to
| >     type(mystr) == type('string'): 
| because the first method necessitates importing another
| module: re: more "overhead".

I also prefer the first form, even though I didn't know about the
types module until now (I haven't needed it yet).  I was idly
wondering about checking the type of instance objects and the overhead
of creating a new instance.  Take for example,

class Foo :
    def __init__( self ) :
        sleep( 50000 ) # take some time initing the object ;-)

obj = Foo()

if type( obj ) is type( Foo() ) :
    print "matches"


This would take execessive time (and maybe resources) to create an
instance of Foo solely to check its type.  I like the
isinstance( obj , Foo ) method since it avoids this unnecessary
overhead.  I suppose one could also do

if obj.__class__ is Foo :
    print "matches"

but I don't think access __class__ is very clean.

-D