Why == doesn't returns true in this case?

Question

I'm jython/python bukkit plugin developer and I'm stuck here. I was always using == in cases like this one, and everything worked perfect. What's the problem? Here's the code:

        lastslot = event.getNewSlot()
        iteminslot = event.getPlayer().getInventory().getItem(lastslot).getType()
        print "Iteminslot: %s "%iteminslot
        print "CurrentKey: %s"%currentKey
        if clickable1 == "false":
           log.info("clickable1 ok")
           if iteminslot == currentKey:
              log.info("iteminslot ok")
              event.getPlayer().addPotionEffect(potion_effect)

When I run code, I get code process to the "clickable1 ok" logger, so it stops checking if iteminslot == currentKey... But when I print out Iteminslot and Currentkey, they are same!

20:41:00 [INFO] Iteminslot: DIAMOND_SWORD
20:41:00 [INFO] CurrentKey: DIAMOND_SWORD
20:41:01 [INFO] clickable1 ok

Where am I making mistakes? Thanks for reading/answering! :)

One might have extra whitespace that you're not noticing. Also, what is their type? Any object can choose how it is printed. One of them could be an object that isn't a string but is printed as one. — BrenBarn, Nov 16 '13 at 19:48
You can check for whitespace as other suggest by using `%r` instead of `%s`. — agf, Nov 16 '13 at 19:48
@agf Now as result I get: `20:49:35 [INFO] Iteminslot: DIAMOND_SWORD 20:49:35 [INFO] CurrentKey: u'DIAMOND_SWORD' 20:49:35 [INFO] clickable1 ok` — Amar Kalabić, Nov 16 '13 at 19:50
@user2971511 Did you use `%r` for `Iteminslot` too? Doesn't look like it. — agf, Nov 16 '13 at 20:00
@user2971511 You should see quotes around it whether it's unicode or bytes. What is `type(Iteminslot)`? — agf, Nov 16 '13 at 20:03

Ashwini Chaudhary · Accepted Answer · 2013-11-16T20:03:26.420

1

You're trying to compare a byte-string with a unicode string, they are not always equal. You should decode/encode them properly before comparing:

>>> 'ć' == u'ć'
False
>>> 'ć' == u'ć'.encode('utf-8')
True
>>> 'ć'.decode('utf-8') == u'ć'
True

Secondly as @BrenBarn mentioned, two objects can print out to a same string. But that doesn't means they're equal:

>>> class foo:
    def __str__(self):
        return 'foo'
...     
>>> class bar:
    def __str__(self):
        return 'foo'
...     
>>> print (foo())
foo
>>> print (bar())
foo
>>> foo == bar
False

edited Nov 16 '13 at 20:03

answered Nov 16 '13 at 19:56

Ashwini Chaudhary

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If the bytestring is ASCII / ASCII compatible they will be though, and we don't know that Iteminslot isn't unicode or contains non-ASCII compatible characters. – agf Nov 16 '13 at 19:57
I'm not sure I understand you, can you provide me an example using names I used above? iteminslot and currentKey... Sorry, but I'm starting to code in Python :D – Amar Kalabić Nov 16 '13 at 20:04
@user2971511 I think your case fits the second example. – Ashwini Chaudhary Nov 16 '13 at 20:08
@hcwhsa but, how can I solve this problem I have? How can I check if they are same? edit: I got it, you helped me. Thanks! – Amar Kalabić Nov 16 '13 at 20:09
@user2971511 You need to check how `org.bukkit.Material` class implements its `__eq__` method. – Ashwini Chaudhary Nov 16 '13 at 20:14

Why == doesn't returns true in this case?

1 Answers1