Question

My question is how can I return a nil from an exception instead of — in the case of using slurp — the file name that would not load and the exception text? Here are the details.

I want the following code to return a nil:

(defn open-csv-file
    "Attempts to open a .csv file and complains if the file is not present."

    [file-name]
        (let [file-data 
            (try 
                (slurp file-name)
                (catch Exception e (.getMessage e)))]
            file-data))

Here is an example of what is being returned now.

bene-cmp.core=> (load-file "src/bene_cmp/core.clj")
#'bene-cmp.core/-main
bene-cmp.core=> (def x  (open-csv-file "test_file.csv"))
#'bene-cmp.core/x
bene-cmp.core=> x
"test_file.csv (No such file or directory)"
bene-cmp.core=> 

I am trying to avoid modifying this function, so that it throws the exception and then having the caller use a try/catch block.

Thank You.

Answer 1

If I understand your question, you just need to change this:

(catch Exception e (.getMessage e)))]

to this:

(catch Exception e))]