344605 - nsIPropertyBag2 should grow a non-throwing get() and hasKey()

Status: RESOLVED FIXED

(Core :: XPCOM, enhancement)

Description

[Robert Sayre]

Using property bags from JS is a pain because getProperty throws when the key isn't found. Examples:

http://lxr.mozilla.org/seamonkey/source/browser/components/feeds/src/FeedWriter.js#67
http://lxr.mozilla.org/seamonkey/source/toolkit/components/feeds/src/FeedProcessor.js#170

Comment 1

[Robert Sayre]

Here's how I would like it to work:

-----------------------------

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

const BAG_CONTRACTID = "@mozilla.org/hash-property-bag;1"
const Ci = Components.interfaces;
const Cc = Components.classes;

var bag = Cc[BAG_CONTRACTID].createInstance(Ci.nsIWritablePropertyBag2);

bag.setPropertyAsAString("foo", "bar");

print("\n\n***************\n");
print("    getProperty() on existing key: " + bag.getProperty("foo"));
print("         hasKey() on existing key: " + bag.hasKey("foo"));
print("            get() on existing key: " + bag.get("foo"));


try {
    bag.getProperty("baz");
}
catch(e) {
    print("getProperty() on non-existent key: " + e.message);
}

print("     hasKey() on non-existent key: " + bag.hasKey("baz"));
print("        get() on non-existent key: " + bag.get("baz"));
print("\n\n***************\n");

-----------------------------

Should print as follows:

***************

    getProperty() on existing key: bar
         hasKey() on existing key: true
            get() on existing key: bar
getProperty() on non-existent key: Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIWritablePropertyBag2.getProperty]
     hasKey() on non-existent key: false
        get() on non-existent key: null


***************

Comment 2

[Robert Sayre]

Attachment: Patch with get() and hasKey()

Here's a strawman.

Comment 3

[Darin Fisher]

Comment on attachment 229178 [details] [diff] [review]
Patch with get() and hasKey()

You need to change the UUID of an interface when you changes its vtable layout or the signature of any of its methods.

s/Astring/AString/

r=darin otherwise

Comment 4

[Robert Sayre]

Attachment: fix darin's comments

Comment 5

[Mike Shaver (:shaver emeritus)]

Comment on attachment 229931 [details] [diff] [review]
fix darin's comments

sr=shaver

Comment 6

[Robert Sayre]

Checking in nsHashPropertyBag.cpp;
/cvsroot/mozilla/xpcom/ds/nsHashPropertyBag.cpp,v  <--  nsHashPropertyBag.cpp
new revision: 1.6; previous revision: 1.5
done
Checking in nsIPropertyBag2.idl;
/cvsroot/mozilla/xpcom/ds/nsIPropertyBag2.idl,v  <--  nsIPropertyBag2.idl
new revision: 1.2; previous revision: 1.1
done

Comment 7

[Boris Zbarsky [:bzbarsky]]

Note bug 375779.