270746 - Exception when I pass @mozilla.org/js/xpc/Exception;1 object to alert() method

Status: RESOLVED INACTIVE

(Core :: XPConnect, defect)

Description

[alexander :surkov (:asurkov)]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.0; rv:1.7.3) Gecko/20040913 Firefox/0.10.1
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7) Gecko/20040616

When I create @mozilla.org/js/xpc/Exception;1 object and query nsIException
interface then I get wrong javascript wrapper of created object, because it
throw exeption when I call toString() method or I try to pass it to alert() method.


Reproducible: Always
Steps to Reproduce:
1. alert(Components.classes["@mozilla.org/js/xpc/Exception;1"].
		createInstance(Components.interfaces.nsIException).toString());
or 

2. alert(Components.classes["@mozilla.org/js/xpc/Exception;1"].
		createInstance(Components.interfaces.nsIException));

Actual Results:  

Exception when I call toString() method:
Error: uncaught exception: [Exception... "Component returned failure code:
0xc1f30001 (NS_ERROR_NOT_INITIALIZED) [nsIXPCException.toString]"  nsresult:
"0xc1f30001 (NS_ERROR_NOT_INITIALIZED)"]

Exception when I pass object to alert() method:
Error: uncaught exception: [Exception... "Could not convert JavaScript argument
arg 0 [nsIDOMWindowInternal.alert]"  nsresult: "0x80570009
(NS_ERROR_XPC_BAD_CONVERT_JS)" ]

Expected Results:  
I expect to see something like this: xpconnect wrapped nsIException

Comment 1

[Boris Zbarsky [:bzbarsky]]

The nsIException interface has a toString() method.  This method overrides the
"native" classinfo toString() that would return "xpconnect wrapped ....".

So the behavior looks correct to me.

Comment 2

[alexander :surkov (:asurkov)]

Any javascript object has to have toString() method to convert self to string. I
think if component replaces toString() method then component should think about
compatibility with javascript rules. I guess this bug is true and it's needed to
move it to XPCOM component.

Comment 3

[Boris Zbarsky [:bzbarsky]]

The point is, the toString method can be anything.  There's no reason my JS
objects can't just throw when toString() is called on them...

Comment 4

[alexander :surkov (:asurkov)]

I agree there is no real reason. But I really don't think It's correct to throw
exception when I try to convert object to string. I think toString() method is
"native" method and it should work always and it shouldn't depend on state of
object. I am accustomed so much to the fact that I can "see" object at any time.
And when I get exception then I'm confused.

I think it's better to return string with error message.

Comment 5

[Boris Zbarsky [:bzbarsky]]

> I think toString() method is "native" method

It's not, really... any object can override toString on itself any time it wants to.

Comment 6

[alexander :surkov (:asurkov)]

I seem javascript objects don't like to throw exceptions and exception throwing
isn't a method of javascript. Can you say me what native javascript object
throws exception?

Comment 7

[timeless]

i've had domwindows or something related to them throw exceptions when i
stringify them. and ie has some properties which throw exceptions when i
stringify them.

Comment 8

[Boris Zbarsky [:bzbarsky]]

What do you mean by "native javascript objects"?  If you mean ECMA-262 objects,
the specification describes exceptions being thrown in a wide variety of
circumstances...

Comment 9

[timeless]

actually, sometimes i get exceptions from tostring (on instances of Array and
Object) just because my global object doesn't like me.

Comment 10

[alexander :surkov (:asurkov)]

When I use toString() method to "see" object then I don't know often type of
object. I should set try/catch instructions when I use toString(). I think it's
inconveniently.

Maybe I'm wrong and method toString() may throw exception in some cases.

Comment 11

[Boris Zbarsky [:bzbarsky]]

Since any object may override its own toString any time it wishes, toString can
in fact do anything at all.

Comment 12

[Gervase Markham [:gerv]]

This is an automated message, with ID "auto-resolve01".

This bug has had no comments for a long time. Statistically, we have found that
bug reports that have not been confirmed by a second user after three months are
highly unlikely to be the source of a fix to the code.

While your input is very important to us, our resources are limited and so we
are asking for your help in focussing our efforts. If you can still reproduce
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Comment 13

[alexander :surkov (:asurkov)]

confrim Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.9a1) Gecko/20050909
SeaMonkey/1.1a

I still belive toString() shouldn't throw any exception

Comment 14

[Boris Zbarsky [:bzbarsky]]

Brendan, shaver, is there any reason not to mark this bug invalid?  There's no
way an uninitialized exeption object can do sane toString, imo...

Comment 15

[BMO Automation]

Per policy at https://wiki.mozilla.org/Bug_Triage/Projects/Bug_Handling/Bug_Husbandry#Inactive_Bugs. If this bug is not an enhancement request or a bug not present in a supported release of Firefox, then it may be reopened.