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    <blockquote> <p>Unfortunately, decorators (to my understanding), are interpreted when the function is defined. Hence it won't have access to instance's value. Is there a way to pass in dynamic data or values from the sub class?</p> </blockquote> <p>The template needs to be called with the <em>name</em> of the relevant attribute; the wrapper can then get that attribute's <em>value</em> dynamically. For example:</p> <pre><code>import functools def expose(attname=None): if attname: def makewrapper(f): @functools.wraps(f) def wrapper(self, *a, **k): attvalue = getattr(self, attname, None) ...use attvalue as needed... return wrapper return makewrapper else: ...same but without the getattr... </code></pre> <p>Note that the complication is only because, judging from the code snippets in your Q, you want to allow the <code>expose</code> decorator to be used both with and without an argument (you could move the <code>if attname</code> guard to live within <code>wrapper</code>, but then you'd uselessly repeat the check at each call -- the code within wrapper may also need to be pretty different in the two cases, I imagine -- so, shoehorning two different control flows into one wrapper may be even more complicated). BTW, this is a dubious design decision, IMHO. But, it's quite separate from your actual Q about "dynamic data".</p> <p>The point is, by using the attribute name as the argument, you empower your decorator to fetch the value dynamically "just in time" when it's needed. Think of it as "an extra level of indirection", that well-known panacea for all difficulties in programming!-)</p>
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    1. POhow to pass in dynamic data to decorators
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    1. USAlex Martelli
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    1. COI am able to do set the value as long as it's defined within the same file: template_dir = "address" @expose(template_dir) But when I try to do: @expose(self.template_dir) and define self.template_dir in the sub class, it says self is undefined. I have edited my Q with an example.
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      1. USsteve
    2. CO@steve, of course: at the time the template executes there **is** no `self`. By passing the attribute name, as I explain, you get an extra level of indirection and completely solve the problem.
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      1. USAlex Martelli
    3. COi think i got this now. so i will have to write another @expose to override the existing one. call @expose(attrname="template_dir"), and write a wrapper that will evaluate the value of template_dir?
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