getting the filename of current input source in pollen.rkt

[Ifeoluwapo Eleyinafe]

I'd like to use the current input source as "filename" to generate a filename.data for storing previously obtained json data from api pulls.

Among the many things I can't figure out is how to get the filename of the file currently being rendered into my pollen.rkt. Is there a way to do this? I've been trawling through the pollen docs on racket and can't find it. I think I can pull from metas using 'here-path but I don't know how to access metas from pollen.rkt. I can do so from the template file but then I won't be able to use the data in my tag definitions.

Any help would be greatly appreciated. Thank you all for helping me out so much already.

- Ife

[Matthew Butterick]

On Mar 28, 2019, at 6:23 AM, Ifeoluwapo Eleyinafe <eleyi...@gmail.com> wrote:

 I think I can pull from metas using 'here-path but I don't know how to access metas from pollen.rkt. I can do so from the template file but then I won't be able to use the data in my tag definitions.

Import `pollen/core` and use `current-metas`:

https://docs.racket-lang.org/pollen/Core.html?q=current-metas#%28def._%28%28lib._pollen%2Fcore..rkt%29._current-metas%29%29

[Ifeoluwapo Eleyinafe]

Thanks so much for the quick reply. So I tried to access (current-metas) from the pollen.rkt but I keep getting false.

I tried creating a test meta with (define-meta ...) but it was not accessible and it wasn't visible on (current-metas).

Tried running (select-from-metas) from pollen.rkt but metas was an unbound identifier.

I'm sure I'm doing something wrong. I'll keep re-reading the documentation.

Thanks much for your help.

[Sorawee Porncharoenwase]

Can we see your pollen.rkt? Anyhow, it’s very likely that you call (current-metas) outside of tag functions.

(current-metas) is “undefined” outside of tag functions, which make sense if you think about it: pollen.rkt can be used by several Pollen markup files, and each markup file can define different metas. Therefore, outside of tag functions, the concept of metas is not well-defined.

On the other hand, a tag function is invoked from markup files, so it's possible to associate metas to (current-metas).

corr

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[Ifeoluwapo Eleyinafe]

Great advice. Thanks so much. So I've defined an arbitrary function:

(define (output-filename meta-source)
   (path->string
        (car (reverse (explode-path (string->path (select-from-metas 'here-path meta-source)))))))

Then I call it from within a tag function like so:

(output-filename (current-metas))

Just want to say thanks again. In hindsight, here are the words from the manual about (current-metas):

"Holds the metas of the current Pollen source. In tag functions, ..."

Have a good evening and I really appreciate your help and that of Mr. Butterick.

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