RE: Java Extension Functions and XT

Subject: RE: Java Extension Functions and XT
From: Kay Michael <Michael.Kay@xxxxxxx>
Date: Wed, 28 Jul 1999 18:08:08 +0100
> So if I understand correctly, when I used <xsl:variable
> name="seed"><xsl:value-of 
> select="string(logon:seed())"/></xsl:variable> I
> created a text macro that was then evaluated on each use. Repeatedly
> inserting and evaluating a text macro caused the function to be called
> repeatedly which in my case caused the value to change.
What the spec says is that this creates a "result tree fragment". It doesn't
say whether it creates it once or whether it does it repeatedly each time
the variable is used. From your evidence xt is doing it repeatedly. SAXON
only does it once, when the variable is declared. I believe that both
behaviours are strictly correct according to the spec. It would also be
correct to evaluate the function repeatedly when you use the "select"
syntax, since there is nothing in the spec to say that a variable should not
be re-evaluated each time it's used.

I think it would be useful if the spec said something about whether or not
extension functions can have side-effects and what to expect if they do.
It's not something the implementor can enforce, of course.

Mike Kay

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