missing return statement in factory pattern c#

Question

I have the following code for my code but it always says the return statement is missing, even though I have put them in a switch list.

public IMap Map(string oldtheme) 
{ 
    switch (oldtheme) 
    { 
        case "archer": return new Archer(); 
        case "craftyblue": return new CraftyBlue(); 
        case "minimal": return new Minimal(); 
        case "mintalicious": return new Mintalicious(); 
        case "misfit": return new Misfit(); 
        case "peach": return new Peach(); 
        case "queen": return new Queen(); 
        case "sketch": return new Sketch(); 
        case "takeaway": return new TakeAwayLemonFresh(); 
        case "lemonfresh": return new TakeAwayLemonFresh(); 
        case "vanilla": return new Vanilla(); 
        case "velvet": return new Velvet(); 
        case "victoriana": return new Victoriana(); 
        case "writer": return new Writer();
    }
}

Wai Ha Lee · Accepted Answer · 2015-04-01T11:17:25.957

You need to handle the case when oldtheme is none of the values you check for.

Depending on your case, I suggest throwing a ArgumentException so you know when it happens. I have added a default case to your switch statement:

public IMap Map(string oldtheme)
{
    switch ( oldtheme )
    {
        case "archer": return new Archer();
        case "craftyblue": return new CraftyBlue();
        case "minimal": return new Minimal();
        case "mintalicious": return new Mintalicious();
        case "misfit": return new Misfit();
        case "peach": return new Peach();
        case "queen": return new Queen();
        case "sketch": return new Sketch();
        case "takeaway": return new TakeAwayLemonFresh();
        case "lemonfresh": return new TakeAwayLemonFresh();
        case "vanilla": return new Vanilla();
        case "velvet": return new Velvet();
        case "victoriana": return new Victoriana();
        case "writer": return new Writer();
        default: throw new ArgumentException("unexpected value of oldtheme");
    }
}

I admit that this is actually better than just returning `null`, so +1. — Dion V., Apr 01 '15 at 11:11

score 1 · Answer 2 · answered Apr 01 '15 at 11:08

1

You lack a default value. Just add;

default: return null;

At the bottom of your switch and you'll be fine.

answered Apr 01 '15 at 11:08

Dion V.

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score 0 · Answer 3 · answered Apr 01 '15 at 11:07

0

What do you want to return if the string is none of those you have in your switch? Your function is missing a return statement for that case.

answered Apr 01 '15 at 11:07

nvoigt

75,013
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score 0 · Answer 4 · answered Apr 01 '15 at 12:08

0

You have to use break after every return command and it will work fine.

answered Apr 01 '15 at 12:08

Andre Korosh Kordasti

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Hi Andre, that's not true. The `break` keyword is only necessary if the control can continue to the next `case`, which it can't because the execution is `return`ed. See [switch statement is return suitable to replace break](http://stackoverflow.com/q/3196163/1364007), for instance for a discussion. – Wai Ha Lee Apr 01 '15 at 16:26

missing return statement in factory pattern c#

4 Answers4