Nathaniel Alfred wrote:
-----Original Message-----
From: Jochen Kuhnle [mailto:[EMAIL PROTECTED]
Sent: Freitag, 27. Mai 2005 15:02
To: [email protected]
Subject: RE: [RFE] Some enhancements to XSP
and "if(expr) {{{{code}}}}" really starts to look bad.
XSP attribute interpolation makes on sense for Java expressions. Therefore
"if(expr){code}" is not really an issue.
Right
I would suggest a syntax as "{?expr}" which must be transformed by a
preprocessor
applied to XSPs and logicsheets:
See below.
<img src="{?logo}.gif"/>
==> <img><xsp:attribute
name="src"><xsp:expr>(logo)+""</xsp:expr>.gif<xsp:attribute></img>
String.valueOf(logo)
<h1>Hello {?username}</h1>
==> <h1>Hello <xsp:expr>(username)+""</xsp:expr></h1>
I'm -1 on this ATM. Let's do step at a time - first let's reduce verbosity in
generating attributes.
The prepocessor should not introduce any new line breaks in order to preserve
the correct line number count for XSLT error messages from the logicsheet.
The preprocessor must understand string and character constants and nested
braces.
Here are a few valid non-trivial expressions:
{?foo.indexOf('}')}
{?foo.indexOf("}")}
{?new String[]{"foo","bar"}[index]}
If the closing brace is missing, the preprocessor shall generate XSP code which
leads to a compilation error:
<h1>Hello {?username}</h1>
==> <h1>Hello <xsp:expr>(username)+""}</xsp:expr></h1>
The replacement can be suppressed, by duplication the "?":
<tt><h1>Hello {??username}</h1></tt> is transformed to
<tt><h1>Hello
<xsp:expr>username</xsp:expr></h1></tt>
There should be no '<xsp:expr>', but rather '{'.
Instead of "?" one could also use another character provided it is sufficiently
unlikely that the sequence curly-char appears in XSP-embedded content or where
XSP can be embedded (XSL). The special character should not be valid at the
beginning of an expression at least for CSS, HTML, Java, Javascript, Perl,
and XSLT. That excludes
+ " * % & ` @ ' ^ ~ ! [ $ - . ( /
but leaves as sensible alternatives
{#expr}
{=expr}
{:expr}
{?expr}
Whatever special character we agree on, it should be always the same in all
contexts and always enabled.
Any preferrences which character to use?
Yes. Given that (a) XSLT already has '{foo}' syntax, and uses '{{foo}}' for
escaping; and given that the only other XSP implementation (AxKit) uses same
syntax as in XSLT, I'm for using that same syntax too.
As for backward compatibility, is is already solved by:
<xsp:page attribute-value-interpolation="no">
Re -1 above: If in future you'd want to implement interpolation in the text as
well, we could add:
<xsp:page text-value-interpolation="no">
(which, too, would preserve backward compatibility)
Vadim
