On 12/07/2011 08:10 PM, Daniel Veillard wrote: > On Mon, Dec 05, 2011 at 02:48:30PM -0700, Eric Blake wrote: >> According to the official XML specification [1], attributes >> can be specified with either ' or " (where the difference is >> that you can use '"' or '"' but must use """, >> and conversely for "'" or "'" vs. '''). But our >> code generation in src/conf prefers to output the '' notation, >> as it is easier to write C string literals for that style. >> Using a consistent style throughout libvirt will make it >> easier for users to copy-and-paste without wondering why we >> switch quoting styles mid-stream. > [...] >> diff --git a/tests/xml2sexprdata/xml2sexpr-escape.xml b/tests/xml2sexprdata/xml2sexpr-escape.xml >> index 6eed578..bca2c81 100644 >> --- a/tests/xml2sexprdata/xml2sexpr-escape.xml >> +++ b/tests/xml2sexprdata/xml2sexpr-escape.xml >> @@ -5,7 +5,7 @@ >> <type>hvm</type> >> <kernel>/var/lib/xen/vmlinuz.2Dn2YT</kernel> >> <initrd>/var/lib/xen/initrd.img.0u-Vhq</initrd> >> - <cmdline> method=http://download.fedora.devel.redhat.com/pub/fedora/linux/core/test/5.91/x86_64/os&version="devel"; </cmdline> >> + <cmdline> method=http://download.fedora.devel.redhat.com/pub/fedora/linux/core/test/5.91/x86_64/os&version="devel"; </cmdline> >> <loader>/usr/lib/xen/boot/hvmloader</loader> > > Actually I dislike for this kind of things. It's semantically > equivalent, and I don't think we should try to enforce arbitrary > requirements which are not needed. This is actually more confusing > for people who do know the XML spec, > "why isn't my example good" > it actually is! The choice of quotes is on purpose to allow easy > serialization when you have ' or " in an attribute value. Requiring > the user to escape is kind of wrong IMHO. But the fact that we _didn't_ have any ' or " in attribute values in all of the conversion is a testament to the fact that we don't want to choose attributes with quoting in the attribute value. > Also the automatic rule won't be able to distinguish " and " within > attribute text content from those within element text content, and > we certainly don't want to make a simili parser in perl or regexps. > Also if someone uses an XML editor on one of our fragment it's very > likely that the ' will be turned into " because the distinction is not > part of the XML infoset (i.e. the amount of data an XML parser should > report to the application) and the tool will serialize back using > his own preferences, and that's just fine. > > I think the inconvenients in that case are not worth the possible > improvement. One of the improvements, which I already have noticed since I wrote the patch, is that it is easier to search the rng files for a particular macro definition. That is, if you KNOW that a syntax-check rule enforced the style of <define name='blah'>...</define>, it is easier to see <ref name='blah'/> and search for the definition; whereas pre-patch, you could see <ref name='blah'/> but not know whether to search for name='blah' or name="blah" to find the counterpart <define>. Notice that my syntax-check is not documenting anything contrary to the user; that is, no where did I change documentation to suggest to the user that they must prefer '' over "". Rather it is just presenting a consistent interface (since 'virsh dumpxml dom' always outputs name='value', then the web pages that document how to interpret 'virsh dumpxml' output should also use name='value'). We could drop the changes to the tests directory, if you'd like (that is, use just patches 2 and 3 for the ease of rng searching and for the consistent documentation, but leaving the test directory as a way to prove that the quoting style doesn't matter). But if you're dead set against this series, I guess it won't hurt things to drop it (I can continue to do a regex search for name=['"]blah when looking for a <def name='blah'> counterpart in rng, which is particularly hard to type at a shell command line, but oh well). Any other opinions? -- Eric Blake eblake@xxxxxxxxxx +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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