I think COBOL is a data centric programming language. Some features are nice and one of this is to "read data into" data structure. If data structure is a group the check on data is later at the point of using. The feature is that I did not to know datatypes or convert something at the time I fill my data structure.
If I think in Swift I need something like read Data into struct or create struct from Data...
(Pseudocode)
struct dataContainer { // declare like data group in COBOL
var x : [UInt8] = Array (count:15, repeating = 0)
var u : UInt64
var b : Int16
var k : [UInt8] = Array (count: 27, repeating = 0)
}
func main () {
let fh = FileHandle ("dummyData")
let flatData : Data (sizeof (DataContainer).fromFileHandle() // read from file data
let myStruct = DataContainer (flatData)
print ("Numeric or error = (myStruct.u)")
}
Is something like this existing or how to do something like this?
is it a fixed size data structure or not / don't care?
do you need array semantics for your "x" and "k" variables or don't really care?
do you want array of 27 UInt8 bytes or a String really?
do you want to see a binary format on disk or does that not matter?
if binary do you need that format be compatible with different endian devices?
do you want to read or write as well?
do you want to read from files only or remote URLs as well?
Here's just one (out of many) possible answers to your question:
struct DataContainer {
var x: [UInt8] // not String?
var u: UInt64
var b: Int16
var k: [UInt8]
}
extension DataContainer: Codable {
init(from file: URL) throws {
let data = try Data(contentsOf: file) // DON'T USE THIS IN PRODUCTION FOR REMOTE URL's
self = try JSONDecoder().decode(Self.self, from: data)
}
func save(to file: URL) throws {
let data = try JSONEncoder().encode(self)
try data.write(to: file) // DON'T USE THIS IN PRODUCTION FOR REMOTE URL's
}
}
let data = try! DataContainer(from: file)
data.save(to: file2)
See a somewhat related question recently discussed, yet it can be miles away from what you are after. There the data structure is externally specified, a fixed binary format.
