如何避免使用引用类型的重复代码？

Question

I've made a method to split address line into separate distinct categories like Region, City, Street and House which are represented by a single class. It follows relatively simple structure.

Address useOther(string Casual, string Other)
    {
        Address
            address = new Address();

        List<string>
            split = new List<string>();
        char[]
            separator = { ',' };
        split.AddRange(
            Casual.Split(
                separator, 
                StringSplitOptions.RemoveEmptyEntries));
        split.AddRange(
            Other.Split(
                separator, 
                StringSplitOptions.RemoveEmptyEntries));

        // Initialize parameters
        split = RemoveBannedTokens(split);

        for (int i = 0; i < split.Count; i++)
        {
            (address.Region, split[i]) = findRegionByName(split[i]);

            if (address.Region != null)
            {
                split[i] = split[i].Replace(address.Region.Name, "");
                break;
            }
        }

        if (address.Region == null)
        {
            address.Region = new Region(region);
        }

        split = ClearSplit(split);

        // Finding region
        for (int i = 0; i < split.Count; i++)
        {
            (address.City, split[i]) = findSityByName(split[i]);

            if (address.City != null)
            {
                split[i] = split[i].Replace(address.City.Name, "");
                break;
            }

        }
        if (address.City == null)
        {
            for (int i = 0; i < split.Count; i++)
            {
                (address.City, split[i]) = findCityByName(split[i], false);

                if (address.City != null)
                {
                    split[i] = split[i].Replace(address.City.Name, "");
                    break;
                }

            }
        }
        if (address.City == null)
            return address;
        split = ClearSplit(split);

        // Finding city
        for (int i = 0; i < split.Count; i++)
        {
            (address.Street, split[i]) = findStreetByName(split[i], address.City);

            if (address.Street != null)
            {
                split[i] = split[i].Replace(address.Street.Name, "");
                break;
            }
        }
        if (address.Street == null && 
            (address.Region.Code.Replace("/", "") + 
             address.City.Code.Replace("/", "")).Length != 13)
            return address;
        split = ClearSplit(split);
        //Finding street

        int
            cityIndex = address.City.Index,
            streetIndex = address.Street.Index;

        for (int i = 0; i < split.Count; i++)
        {
            split[i] = split[i].Replace("б/н", "");
        }
        address.House = findNumbers(split.ToArray(), cityIndex, streetIndex);

        return address;
    }
    

If you can see repetition goes like this

for (int i = 0; i < split.Count; i++)
{
    (address.Something, split[i]) = findSomethingByName(split[i]);

    if (address.Something != null)
    {
        //do this thing
        break;
    }

}
if (address.Something == null)
    //try other thing
split = ClearSplit(split);

I want to avoid this repetition and have something of an array or foreach loop but couldn't find a clear way of making an array with reference values or a foreach reference loop that would work with null values properly. I have thought about making a function with specified inputs and outputs but decide it would only harm ability to read my code, which I'm trying to improve here.

Answer 1

Let me try to demonstrate your problem and my proposal.

Assumptions

1. Your class has several similiar properties, all with value of String .
2. You have to keep the properties, because they may be required by other frameworks.
3. You have repeative code to work with the properties.

OldAddress

public class OldAddress
{
    public string City { get; set; }
    public string Region { get; set; }
}

Old Program

public class Program
{

    static OldAddress oldAddress;

    public static string GetFromDataSource(string prop)
    {
        return null;//should return your real value
    }

    public static void AssignValueOldWay()
    {
        if (oldAddress.City != null)
        {
            oldAddress.City = GetFromDataSource("City");
        }
        if (oldAddress.Region != null)
        {
            oldAddress.Region = GetFromDataSource("Region");
        }
        // more...
    }
}

NewAddress

public class NewAddress
{
    public static string[] PropNames = { "City", "Region" };
    public NewAddress()
    {
        props = new Dictionary<string, string>();
        foreach (string prop in PropNames)
        {
            props.Add(prop, "");
        }
    }

    public string City
    {
        get
        {
            return GetProperty("City");
        }
        set
        {
            SetProperty("City", value);
        }
    }
    public string Region
    {
        get
        {
            return GetProperty("Region");
        }
        set
        {
            SetProperty("Region", value);
        }
    }

    private Dictionary<string, string> props;

    public void SetProperty(string prop, string value)
    {
        props[prop] = value;
    }

    public string GetProperty(string prop)
    {
        return props[prop];
    }

}

New Program

public class Program
{

    public static string GetFromDataSource(string prop)
    {
        return null;//should return your real value
    }

    static NewAddress newAddress;

    public static void AssignValueNewWay()
    {
        foreach (string prop in NewAddress.PropNames)
        {
            if (newAddress.GetProperty(prop) != null)
            {
                newAddress.SetProperty(prop, GetFromDataSource(prop));
            }
        }
    }
}

Note my code is just to demonstrate the idea, not optimized for runtime exceptions or bad styles such as public fields, or magic strings.

Answer 2

After some thinking and looking on how I could manage this, I have decided to follow JAlex advise. For now I don't think this change is necessary, so I leave it be for now. What I will do is I would try make this more readable by using additional spaces and comments. As of for now my method looks something like this (after a bit of tweaking here and there) and I'm more or less happy with how readable it is

Address useOther(string Casual, string Other)
{
    Address address = 
        new Address();
    //Initialize address

    List<string> split = 
        new List<string>();
    char[] separator = 
    { 
        ',' 
    };
    //Initialize split and separators

    split.AddRange(Casual.Split(separator));
    split.AddRange(Other .Split(separator));
    RemoveBannedTokens(ref split);
    //Fill split



    for (int i = 0; i < split.Count; i++)
    {
        (address.Region, split[i]) = 
            findRegionByName(split[i]);

        if (address.Region != null)
            break;
    }
    //Trying to find region

    if (address.Region == null)
        address.Region = new Region(region);
    //If Region is not found

    ClearSplit(ref split);
    //Get rid of empty strings



    for (int i = 0; i < split.Count; i++)
    {
        (address.City, split[i]) = 
            findSityByName(split[i]);

        if (address.City != null)
            break;
    }
    //Trying to find city

    if (address.City == null)
    {
        for (int i = 0; i < split.Count; i++)
        {
            (address.City, split[i]) = 
                findSityByName(split[i], false);

            if (address.City != null)
                break;
        }
    }
    //Trying to find city with additional params

    if (address.City == null)
        return address;
    //If City is not found

    ClearSplit(ref split);
    //Get rid of empty strings



    for (int i = 0; i < split.Count; i++)
    {
        (address.Street, split[i]) = 
            findStreetByName(split[i], address.City);

        if (address.Street != null)
            break;
    }
    //Trying to find street

    string code =
        address.Region.Code.Replace("/", "") +
        address.City.Code  .Replace("/", "");
    //Initialize code

    if (address.Street == null && code.Length != 13)
        return address;
    //If Street is not found and address is not complete

    ClearSplit(ref split);
    //Finding street

    address.House = findNumbers(split);
    //Trying to find house

    return address;
}

Answer 3

I had some spare time, so I decided to refactor your code as a mental exercise for myself.

I still wanted to post my solution in case you are interested in seeing it. The most fundamental shift is that I oriented my thoughts from imperative programming to functional programming which resulted in a more concise code, and for people used to this paradigm, a much more readable code.

Address userOther(string Casual, string Other)
{
    var tokens = RemoveBannedTokens(Casual.Split(',', StringSplitOptions.RemoveEmptyEntries)
                                          .Concat(Other.Split(',', StringSplitOptions.RemoveEmptyEntries))
                                          .ToList());

    //Region
    var regionResult = tokens.Select(findRegionByName).FirstOrDefault(t => t.Item1 != null);
    regionResult = regionResult == default ? (region, string.Empty) : regionResult;
    tokens.Remove(regionResult.Item2);

    //City
    var cityResult = tokens.Select(findSityByName).FirstOrDefault(t => t.Item1 != null);
    cityResult = cityResult == default ? tokens.Select(t => findCityByName(t, false)).FirstOrDefault(t => t.Item1 != null) : cityResult;
    cityResult = cityResult == default ? (default(City), string.Empty) : cityResult;
    if (cityResult.Item1 == null)
    {
        return new Address(regionResult.Item1);
    }
    tokens.Remove(cityResult.Item2);

    //Street
    var streetResult = tokens.Select(t => findStreetByName(t, cityResult.Item1)).FirstOrDefault(t => t.Item1 != null);
    if (streetResult.Item1 == null &&
        (regionResult.Item1.Code.Replace("/", "") + cityResult.Item1.Code.Replace("/", "")).Length != 13)
    {
        return new Address(regionResult.Item1, cityResult.Item1);
    }
    tokens.Remove(streetResult.Item2);

    return new Address(regionResult.Item1,
                       cityResult.Item1,
                       streetResult.Item1,
                       findNumbers(tokens.Select(t => t.Replace("б/н", "")).ToArray(), cityResult.Item1.Index, streetResult.Item1.Index));
}

A few things to note:

• Since you didn't provided some methods used by this one, I was unable to test the real behavior of this approach
• I assumed that the returned second item of tuple from methods findXXXByName was the same as the value provided and didn't bother to update tokens[i] with it
• the variable region is provided nowhere in your example, but I still decided to keep it as is
• I created Address instances just when returning them, which forced me to declare multiple constructors (which you may not currently have)
• I assumed that ClearSplit() was just removing empty strings from the tokens

I hope you will find this bit of code valuable for your career path and personnal learning.