string literal or NoneType

[castironpi at gmail.com]

On Mar 15, 10:27 am, menosa... at gmail.com wrote:
> hi all
> i want to check a condition and if true should return a filename
> string  from a list.if the condition is false i am returning a
> ""  (string literal)..
>
> retv=""
> if  somecondition:
>     retv=mylist[x]
> ...
> return retv
>
> The calling function will check the return value and print the
> filename if it is not """.
> in the calling function i can code
> if returnval !="":
>     print "filename is:",returnval
> else:
>     print "no filename found"
>
> what i want to know is ,should i rewrite the  if returnval !=""  as
>
> if returnval:
>    print "filename is:",returnval
> else:
>     print "no filename found"
>
> or is the way i coded the right way ? i am little confused here
> Someone suggested that i make a variable retv None and if the
> condition true then set retv as filename ,
>
> retv=None
> if somecondition:
>     retv=mylist[x]
>
> ...
> return retv
>
> which approach is correct..? can someone help please
> vincent

One possibility:

def fun( ..., testpair, ... ):
    if  somecondition:
        testpair[ True ]( mylist[x] )
    else:
        testpair[ False ]()

.  However 'fun' knows "too much for its scope" by varying call
signature.

Call it by:

fun( ...,
   { True: partial( print, 'filename is:' ),
     False: partial( print, 'no filename found' )
   }, ... )

, which relies even MORE on the particulars of how 'fun' calls.


Reversed:

    return somecondition, partial( mylist.__getitem__, x )

cond, dataf= fun( ... )
if cond:
   print( 'filename is ', dataf() )
else:
   print( 'no filename found' )


, which leave different amounts of genericity/genericness/generality
to work in.