[BUG] Dynamic scoping of project-plist in preparation-function

[BUG] Dynamic scoping of project-plist in preparation-function

[Arun Isaac]

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The org mode manual says "The project property list is scoped into this
call as the variable project-plist". But, ox-publish.el has lexical
binding enabled, and the variable project-plist doesn't seem to be
accessible from the executed preparation-function. When I try to access
the variable, I get a (void-variable project-plist) error.

Please find attached a minimal elisp file to reproduce the bug.

emacs -Q -l preparation-function-dynamic-scoping.el

My understanding of dynamic and lexical binding is a little foggy. So,
do let me know if I'm missing something.

Regards,
Arun Isaac.


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Re: [BUG] Dynamic scoping of project-plist in preparation-function

[Nicolas Goaziou]

Hello,

Arun Isaac <arunisaac@systemreboot.net> writes:

> The org mode manual says "The project property list is scoped into this
> call as the variable project-plist". But, ox-publish.el has lexical
> binding enabled, and the variable project-plist doesn't seem to be
> accessible from the executed preparation-function. When I try to access
> the variable, I get a (void-variable project-plist) error.
>
> Please find attached a minimal elisp file to reproduce the bug.
>
> emacs -Q -l preparation-function-dynamic-scoping.el
>
> My understanding of dynamic and lexical binding is a little foggy. So,
> do let me know if I'm missing something.

There are two ways to handle this.

1. Create a new global variable, with appropriate prefix, to hold
   project plist, e.g., `org-publish-project-plist';

2. Require preparation functions to accept one parameter, the project
   plist.

I'd favor the second one. In any case, the manual should be updated
accordingly.

WDYT?

Regards,

-- 
Nicolas Goaziou

Re: [BUG] Dynamic scoping of project-plist in preparation-function

[Arun Isaac]

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> 2. Require preparation functions to accept one parameter, the project
>    plist.

I think adding project-plist as a parameter to preparation functions is
definitely more elegant.

But, I also came across this old thread where it was noted that making
project-plist a proper parameter, instead of it being dynamically scoped
into the preparation function, would break a lot of code.

https://lists.gnu.org/archive/html/emacs-orgmode/2010-03/msg00016.html

But now, with org moving to lexical binding, I think it is time to make
project-plist a proper parameter, despite the costs of doing so.

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Re: [BUG] Dynamic scoping of project-plist in preparation-function

[Nicolas Goaziou]

Hello,

Arun Isaac <arunisaac@systemreboot.net> writes:

>> 2. Require preparation functions to accept one parameter, the project
>>    plist.
>
> I think adding project-plist as a parameter to preparation functions is
> definitely more elegant.

Done in 5cd793c.

> But, I also came across this old thread where it was noted that making
> project-plist a proper parameter, instead of it being dynamically scoped
> into the preparation function, would break a lot of code.

Bad code deserves to be broken anyway.

More seriously, the fix is trivial, so I don't think this is an issue.

Thank you for the feedback.

Regards,

-- 
Nicolas Goaziou

Re: [BUG] Dynamic scoping of project-plist in preparation-function

[Arun Isaac]

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> Done in 5cd793c.

After 5cd793c, the documentation for the preparation function says
"Each preparation function is called with a single argument, the project
property". This could be clearer if it is "... the project property
list", as it is in the documentation for the completion function.

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Re: [BUG] Dynamic scoping of project-plist in preparation-function

[Nicolas Goaziou]

Arun Isaac <arunisaac@systemreboot.net> writes:

> After 5cd793c, the documentation for the preparation function says
> "Each preparation function is called with a single argument, the project
> property". This could be clearer if it is "... the project property
> list", as it is in the documentation for the completion function.

Indeed, that's a typo. Fixed. Thank you.

Regards,