"Frank Millman" <fr...@chagford.com>:
> "Joonas Liik" wrote in message
> news:cab1gnptp0gd4s4kx07r1ujrnuxtoij4vf5unye1cfr_y0xv...@mail.gmail.com...
>> i should note tho that this example is very ad-hoc, i'm no xml expert
>> just know a bit about xml entities. if you decide to go this route
>> there are probably some much better tested functions out there to
>> escape text for storage in xml documents.
>
> Thanks very much, Joonas.
>
> I understand now, and it seems to work fine.
>
> As a bonus, I can now include '&' in my attributes in the future if the
> need arises.
>
> Much appreciated.
XML attributes are ridiculously complicated. From the standard:
Before the value of an attribute is passed to the application or
checked for validity, the XML processor MUST normalize the attribute
value by applying the algorithm below, or by using some other method
such that the value passed to the application is the same as that
produced by the algorithm.
1. All line breaks MUST have been normalized on input to #xA as
described in 2.11 End-of-Line Handling, so the rest of this
algorithm operates on text normalized in this way.
2. Begin with a normalized value consisting of the empty string.
3. For each character, entity reference, or character reference in
the unnormalized attribute value, beginning with the first and
continuing to the last, do the following:
* For a character reference, append the referenced character to
the normalized value.
* For an entity reference, recursively apply step 3 of this
algorithm to the replacement text of the entity.
* For a white space character (#x20, #xD, #xA, #x9), append a
space character (#x20) to the normalized value.
* For another character, append the character to the normalized
value.
If the attribute type is not CDATA, then the XML processor MUST
further process the normalized attribute value by discarding any
leading and trailing space (#x20) characters, and by replacing
sequences of space (#x20) characters by a single space (#x20)
character.
Note that if the unnormalized attribute value contains a character
reference to a white space character other than space (#x20), the
normalized value contains the referenced character itself (#xD, #xA
or #x9). This contrasts with the case where the unnormalized value
contains a white space character (not a reference), which is replaced
with a space character (#x20) in the normalized value and also
contrasts with the case where the unnormalized value contains an
entity reference whose replacement text contains a white space
character; being recursively processed, the white space character is
replaced with a space character (#x20) in the normalized value.
All attributes for which no declaration has been read SHOULD be
treated by a non-validating processor as if declared CDATA.
It is an error if an attribute value contains a reference to an
entity for which no declaration has been read.
Following are examples of attribute normalization. Given the
following declarations:
<!ENTITY d "
">
<!ENTITY a "
">
<!ENTITY da "
">
the attribute specifications in the left column below would be
normalized to the character sequences of the middle column if the
attribute a is declared NMTOKENS and to those of the right columns if
a is declared CDATA.
=================================================================
Attribute specification: a="
xyz"
a is NMTOKENS: x y z
a is CDATA: #x20 #x20 x y z
=================================================================
Attribute specification: a="&d;&d;A&a; &a;B&da;"
a is NMTOKENS: A #x20 B
a is CDATA: #x20 #x20 A #x20 #x20 #x20 B #x20 #x20
=================================================================
Attribute specification: a="

A

B
"
a is NMTOKENS: #xD #xD A #xA #xA B #xD #xA
a is CDATA: #xD #xD A #xA #xA B #xD #xA
=================================================================
Note that the last example is invalid (but well-formed) if a is
declared to be of type NMTOKENS.
<URL: https://www.w3.org/TR/REC-xml/#AVNormalize>
Marko
--
https://mail.python.org/mailman/listinfo/python-list
