language with dynamic binding. So you may as well assume that the
compiler has just internally renamed every variable declaration and
variable reference so that they all have different names and
so "scope"
isn't an issue when the templates are being executed.
Sure, you could modify that vision as each 'layer' in the variable stack being
the namespace to the variables contained on that layer :) therefore making each
variable unique:
layer1:x = foo
layer2:x = bar
However, I personally think its much easier to visualise the processor being
blind to variables that are not on the top of the variable stack, and the only
way to get them there is to pass them on using xsl:with-params.
cheers
andrew
-----Original Message-----
From: David Carlisle [mailto:davidc(_at_)nag(_dot_)co(_dot_)uk]
Sent: 14 February 2003 12:34
To: xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com
Subject: Re: [xsl] Reference to variable cannot be resolved.
As I understand it, variables are scoped using a 'variable stack' -
when a new template is matched, a new 'layer' is added to the stack
that will contain the variables declared in that template. Should a
new template be called/applied in the middle of that
template, then a
new layer is added to the stack.
That's describing the efect in terms of the run time dynamic
behaviour.
A more declarative description (which is the model in my head, which
explains why I said "you can have two variables...") is that
each variable
has a (hidden) unique name. when you go $x then it refers to some
variable that was defined with name="x", and you can tell
which one that
was statically by the position of the reference in the program: it
doesn't depend on the calling order of the templates as it would in a
language with dynamic binding. So you may as well assume that the
compiler has just internally renamed every variable declaration and
variable reference so that they all have different names and
so "scope"
isn't an issue when the templates are being executed.
Of course an actual implementation probably does something completely
different again but who cares about implementations:-)
David
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