Add S3-method based formatting

[bobjansen]

This would allow definition of formatting methods per S3-class. As a proof of concept, I've added pander to do this as done in your SO answer.

[daroczig]

@bobjansen -- so sorry for the long delay with my reply here :(

So I was not sure how to do this properly and played around a little bit trying to figure out how to be able to pass parameters to pander and keep the API similar to the other formatters. After all, I think we can limit a log call to one object at a time so thus we can pass optional params to pander down ... does it make sense?

This way we do not need the extra S3 step as pander is already an S3 method.

Please see the just pushed commit and let me know what you think.

On the other hand, do you want to pass multiple objects to the same log call and would rather skip the option to pass optional params to pander or whatever the S3 method dispatches?

[codecov-io]

Codecov Report

Merging #22 into master will decrease coverage by 0.39%.
The diff coverage is 0%.

@@           Coverage Diff            @@
##           master     #22     +/-   ##
========================================
- Coverage   72.89%   72.5%   -0.4%     
========================================
  Files          11      11             
  Lines         369     371      +2     
========================================
  Hits          269     269             
- Misses        100     102      +2

Impacted Files	Coverage Δ
R/formatters.R	80.85% <0%> (-3.6%)	⬇️

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[daroczig]

Example run:

> log_formatter(formatter_pander)
> log_info('42')
INFO [2019-07-25 09:31:34] 42
> log_info(40 + 2)
INFO [2019-07-25 09:31:37] _42_
> log_info(head(iris))
INFO [2019-07-25 09:31:41] 
INFO [2019-07-25 09:31:41] -------------------------------------------------------------------
INFO [2019-07-25 09:31:41]  Sepal.Length   Sepal.Width   Petal.Length   Petal.Width   Species 
INFO [2019-07-25 09:31:41] -------------- ------------- -------------- ------------- ---------
INFO [2019-07-25 09:31:41]      5.1            3.5           1.4            0.2       setosa  
INFO [2019-07-25 09:31:41] 
INFO [2019-07-25 09:31:41]      4.9             3            1.4            0.2       setosa  
INFO [2019-07-25 09:31:41] 
INFO [2019-07-25 09:31:41]      4.7            3.2           1.3            0.2       setosa  
INFO [2019-07-25 09:31:41] 
INFO [2019-07-25 09:31:41]      4.6            3.1           1.5            0.2       setosa  
INFO [2019-07-25 09:31:41] 
INFO [2019-07-25 09:31:41]       5             3.6           1.4            0.2       setosa  
INFO [2019-07-25 09:31:41] 
INFO [2019-07-25 09:31:41]      5.4            3.9           1.7            0.4       setosa  
INFO [2019-07-25 09:31:41] -------------------------------------------------------------------
INFO [2019-07-25 09:31:41] 
> log_info(head(iris), style = 'simple')
INFO [2019-07-25 09:31:43] 
INFO [2019-07-25 09:31:43] 
INFO [2019-07-25 09:31:43]  Sepal.Length   Sepal.Width   Petal.Length   Petal.Width   Species 
INFO [2019-07-25 09:31:43] -------------- ------------- -------------- ------------- ---------
INFO [2019-07-25 09:31:43]      5.1            3.5           1.4            0.2       setosa  
INFO [2019-07-25 09:31:43]      4.9             3            1.4            0.2       setosa  
INFO [2019-07-25 09:31:43]      4.7            3.2           1.3            0.2       setosa  
INFO [2019-07-25 09:31:43]      4.6            3.1           1.5            0.2       setosa  
INFO [2019-07-25 09:31:43]       5             3.6           1.4            0.2       setosa  
INFO [2019-07-25 09:31:43]      5.4            3.9           1.7            0.4       setosa  
INFO [2019-07-25 09:31:43] 
> log_info(lm(hp ~ wt, mtcars))
INFO [2019-07-25 09:31:46] 
INFO [2019-07-25 09:31:46] ----------------------------------------------------------------
INFO [2019-07-25 09:31:46]               Estimate   Std. Error   t value    Pr(>|t|)  
INFO [2019-07-25 09:31:46] ----------------- ---------- ------------ ---------- -----------
INFO [2019-07-25 09:31:46]  **(Intercept)**    -1.821      32.32      -0.05633    0.9555   
INFO [2019-07-25 09:31:46] 
INFO [2019-07-25 09:31:46]      **wt**         46.16       9.625       4.796     4.146e-05 
INFO [2019-07-25 09:31:46] ----------------------------------------------------------------
INFO [2019-07-25 09:31:46] 
INFO [2019-07-25 09:31:46] Table: Fitting linear model: hp ~ wt
INFO [2019-07-25 09:31:46] 

[bobjansen]

Apologies for taking so long, this looks good! I've rebased the commits into one.

To your question: I don't think I would want to log multiple objects at once.

[bobjansen]

Thanks for this! Do you have any plans for an update of the package on CRAN?

[daroczig]

Yeah, I'm waiting for my botor pkg to get accepted there so that I can merge #35 and then I'll push an update to CRAN -- no ETA though, I've started that process at the very beginning of Sept 🤷‍♂️

[daroczig]

See also #40