python check string for emptieness - is this the elegant way

Question

if var is not None and var !="" and var !=" ":
   # todo

can I write it like this?:

if var: 
   # todo

var is only String type.

@aug Not since OP wants whitespace to count as empty strings as well. — kqr, Sep 07 '13 at 08:26

score 11 · Accepted Answer · answered Sep 07 '13 at 08:06

11

If you want to filter out space-only string (" "):

if var and var.strip():
    # ...

Becasue string that contain spaces is evaludated as True if used as predicate:

>>> bool("")
False

>>> bool("  ")
True

answered Sep 07 '13 at 08:06

falsetru

1

I think `if var.strip():` is equivalent to that. – Shashank Sep 07 '13 at 08:15
4

@ShashankGupta: Not if `var` could be `None`. – Martijn Pieters Sep 07 '13 at 08:19
@MartijnPieters Ah good point :) – Shashank Sep 07 '13 at 08:20
Although obviously if `' '` is the *only* whitespace string that should be considered false, whereas `' ' * 2` or `'\t'` should be considered true as in the code in the question, then the answer is different :-) – Steve Jessop Sep 07 '13 at 09:01

1 Answers1