[Rd] Unique ID for conditions to supress/rethrow selected conditions?

[Duncan Murdoch]

On 16/04/2023 10:49 a.m., nospam using altfeld-im.de wrote:
> On Sun, 2023-04-16 at 13:52 +0200, Iñaki Ucar wrote:
> 
>> I agree that something like this would be a nice addition. With the
>> current condition system, it would be certainly easy (but quite a lot
>> of work) to define a hierarchy of built-in conditions, and then use
>> them consistently throughout base R.
> 
> Yes, a typed condition system would be great.

Why don't you contribute some patches to the sources to implement it in 
some particular area?  You can follow the pattern that is used in the 
gram.y file:  identify a class of messages, and what information is 
useful in them.  Write a function or functions to generate errors or 
warnings with that class, and possibly a subclass.  Then replace each 
error() and warning() call in some group of functions with a call to 
your function(s).

Even better, since that's a lot of work:  propose it as a project to be 
funded by the R Foundation, or as a shorter project in some other way. 
There are now quite a number of ways to contribute to R, e.g. see

   https://github.com/r-devel/rdevguide

Duncan Murdoch

> I have two other ideas:
> 
> 
> 
> By reading the "R messages" and "preparing translactions" sections of the "R extensions manual"
> 
> https://cran.r-project.org/doc/manuals/r-release/R-exts.html#R-messages
> 
> I was thinking about using the "unique" R message texts (which are the msgid in the *.po files,
> see e.g. https://github.com/r-devel/r-svn/blob/60a4db2171835067999e96fd2751b6b42c6a6ebc/src/library/base/po/de.po#L892)
> to maintain a unique ID (not dependent on the actual translation into the current language).
> 
> A "simple" solution could be to pre- or postfix each message text with an ID, for example this code here
> 
>       else errorcall(call, _("non-numeric argument to function"));
>       # https://github.com/r-devel/r-svn/blob/49597237842697595755415cf9147da26c8d1088/src/main/complex.c#L347
> 
> would become
> 
>       else errorcall(call, _("non-numeric argument to function [47]"));
> or
>       else errorcall(call, _("[47] non-numeric argument to function"));
> 
> Now the ID could be extracted more easily (at least for base R condition messages)...
> 
> This would even be back-portable to older R versions to make condition IDs broadly available "in the wild".
> Another way to introduce an ID for each condition in base R would be ("the hard way")
> 
> 1) by refactoring each and every code location with an embedded message string to use a centralized
>     key/msg_text data structure to "look up" the appropriate message text and
> 
> 2) use the key to enrich the condition as unique ID (e.g. as an attribute in the condition object).
> 
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