undefined function / function not found - r

Question

I created a package for R to learn how to develop these things and I got a error that I can't resolve. I saw this error was nor uncommon but I could not find a solution.
This is the code of my package (pretty simple):
absconc<-function(x,a,b,...)
{
a<-as.numeric(a)
b<-as.numeric(b)
absconcCalc<- function(x,a,b,...)
{
conc<- (x*a)+b
}
conc<-absconcCalc(x,a,b,...)
print.absconc<- function(x,a,b,...)
{
cat("Slope:")
cat(a,"\n")
cat("Intercept:")
cat(b,"\n")
cat("Concentration:")
cat(conc)
}
print.absconc(x,a,b)
}
I created the package using package.skeleton and it worked like a charm, even the building of the package using R CMD build absconc worked.
The problem was when I trying to use the package it gave me Error: could not find function "absconc".
I though it was a problem coming from NAMESPACE and the export so I tried exporting the functions using export(absconc). When I tried building that I got an error saying:
Error in namespaceExport(ns, exports) :
undefined exports: absconc, absconcCalc, print.absconc
I am now scratching my head to understand why my function are not recognized.
I would appreciate some help on that as this is only my first package.
EDIT: here are my files (A bit messy, sorry)
https://github.com/Frisacher/absconc

Answer 1

You should not edit NAMESPACE by hand. Insert the line #' #export at the top of your R file and run devtools::document() in the console. This will do what is necessary for you.
Now you can execute devtools::load_all() and run your function.
More explicitly:
1) Create a folder named "R" below the root directory and create an R script that contains your function as Martin Morgan suggested in the comments.
2) Add a roxygen comment to your R script to export it:
#' #export
absconc<-function(x,a,b,...)
{
a<-as.numeric(a)
b<-as.numeric(b)
...
}
3) Execute devtools::document() in the console.
> devtools::document()
Updating absconc documentation
Loading absconc
Writing NAMESPACE
4) Load your package with devtools::load_all().
> devtools::load_all()
Loading absconc
5) Run your function.
> absconc(1,2,3)
Slope:2
Intercept:3
Concentration:5