Hello, I start learning to use Bioconductor and I have a problem with showClass() function. When I'm knitting I get this error in the R Markdown window of RStudio, even though the line works perfectly fine in the Console window.

> showClass("BSgenome")

Error in getClass(Class) : "BSgenome" is not a defined class Calls: <Anonymous> ... withVisible -> eval -> eval -> showClass -> getClass

> sessionInfo()

R version 3.6.0 (2019-04-26)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 17134)

Matrix products: default

Random number generation:
 RNG:     Mersenne-Twister 
 Normal:  Inversion 
 Sample:  Rounding 

locale:
[1] LC_COLLATE=English_United States.1252 
[2] LC_CTYPE=English_United States.1252   
[3] LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C                          
[5] LC_TIME=English_United States.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods  
[7] base     

loaded via a namespace (and not attached):
 [1] Rcpp_1.0.1       digest_0.6.18    dbplyr_1.4.0    
 [4] crayon_1.3.4     dplyr_0.8.0.1    assertthat_0.2.1
 [7] R6_2.4.0         DBI_1.0.0        magrittr_1.5    
[10] evaluate_0.13    pillar_1.3.1     rlang_0.3.4     
[13] rstudioapi_0.10  rmarkdown_1.12   tools_3.6.0     
[16] glue_1.3.1       purrr_0.3.2      yaml_2.2.0      
[19] xfun_0.6         compiler_3.6.0   pkgconfig_2.0.2 
[22] htmltools_0.3.6  knitr_1.22       tidyselect_0.2.5
[25] tibble_2.1.1     

Your sessionInfo indicates that you haven't loaded the BSgenome package yet. And if you ask for the class of an undefined class, you should get an error like what you see:

> showClass("BSgenome")
Error in getClass(Class) : "BSgenome" is not a defined class

If I do

---
title: the title
author: James W. MacDonald
output:
   BiocStyle::html_document:
       toc_float: true


---

# In the beginning

There was a classs...

 ```{r}

suppressPackageStartupMessages(library(BSgenome))
showClass("BSgenome")


 ```

and it was good.

And then I render it, I get