Alternate method to dependent, nested if statements to check multiple states
- by octopusgrabbus
Is there an easier way to process multiple true/false states than using nested if statements? I think there is, and it would be to create a sequence of states, and then use a function like when to determine if all states were true, and drop out if not. I am asking the question to make sure there is not a preferred Clojure way to do this.
Here is the background of my problem:
I have an application that depends on quite a few input files. The application depends on .csv data reports; column headers for each report (.csv files also), so each sequence in the sequence of sequences can be zipped together with its columns for the purposes of creating a smaller sequence; and column files for output data.
I use the following functions to find out if a file is present:
(defn kind [filename]
(let [f (File. filename)]
(cond
(.isFile f) "file"
(.isDirectory f) "directory"
(.exists f) "other"
:else "(cannot be found)" )))
(defn look-for
[filename expected-type]
(let [find-status (kind-stat filename expected-type)]
find-status))
And here are the first few lines of a multiple if which looks ugly and is hard to maintain:
(defn extract-re-values
"Plain old-fashioned sub-routine to process real-estate values / 3rd Q re bills extract."
[opts]
(if (= (utl/look-for (:ifm1 opts) "f") 0) ; got re columns?
(if (= (utl/look-for (:ifn1 opts) "f") 0) ; got re data?
(if (= (utl/look-for (:ifm3 opts) "f") 0) ; got re values output columns?
(if (= (utl/look-for (:ifm4 opts) "f") 0) ; got re_mixed_use_ratio columns?
(let [re-in-col-nams (first (utl/fetch-csv-data (:ifm1 opts)))
re-in-data (utl/fetch-csv-data (:ifn1 opts))
re-val-cols-out (first (utl/fetch-csv-data (:ifm3 opts)))
mu-val-cols-out (first (utl/fetch-csv-data (:ifm4 opts)))
chk-results (utl/chk-seq-len re-in-col-nams (first re-in-data) re-rec-count)]
I am not looking for a discussion of the best way, but what is in Clojure that facilitates solving a problem like this.
