Cobra Forums

"""
cobra --version
Cobra 0.9.6 on .NET CLR v4.0.30319 on Microsoft Windows NT 6.1.7601 Service Pack 1
"""

class Loader
    var contents
    var offset as int

    def readByte as int
        require
            .contents <> nil
        body
            byte = .contents[.offset] # this is where Xamarin Studio points when the exception is thrown
            .offset = .offset + 1
            return byte

    def load(filename as String)
        .offset = 0
        .contents = File.readAllBytes(filename)

        if .readByte <> 65 # if it doesn't equal 'A', we have a problem
            print "Invalid header\n"

class Program
    def main
        loader as Loader? = Loader()
        loader.load('test.txt') # simply contains ABCDE
        print "Done.\n"

class Loader
    var contents as uint8[]?
    ...

body
    contents = .contents to uint8[]  # the type will be inferred via the cast operation
    byte = contents[.offset]
    ...

class Loader
    var contents as uint8[]

def readByte as int
        require
            .contents <> nil
        body
            byte = .contents[.offset]   # no Exception now
            .offset = .offset + 1
            #return byte # <<- Invalid cast Exception cos byte is actually dynamic/Object 
            return Convert.toInt32(byte) 

    def load(filename as String)
        .offset = 0
    .contents = File.readAllBytes(filename).toList  # store as a collection/List
        if .readByte <> 65 # if it doesn't equal 'A', we have a problem
            print "Invalid header\n"

class Loader
    var contents = @[0u8]  # initialise to a one element array of uint8
    var offset as int
    
        
    def readByte as int
        require
            .contents.length # consequent to the initialisation above

byteSubrange = .contents[0:4]  # first 3 bytes (start:end+1)
string = System.Text.Encoding.utf8.getString(byteSubrange)
# print String  # 'ABCD'