Difference between BuildUp and Resolve

Question

I am playing around with Unity Library, as at my workplace it is highly used, so wanted to understand its different behaviours.

I am confused about BuildUp and Resolve because they seem to do same thing so i am not getting when it is suitable to use BuildUp and when Resolve.

Am i missing something ?

Here is example :

public class Decorations
{
    public string Header { get; set; }

    public string Footer { get; set; }
}

public class Printer
{
    internal void Print(string message)
    {
        Console.WriteLine("HEADER: {0}", this.Decorations != null
            && this.Decorations.Header != null
                ? this.Decorations.Header
                : string.Empty);
        Console.WriteLine(message);
        Console.WriteLine("FOOTER: {0}", this.Decorations != null
            && this.Decorations.Footer != null
                ? this.Decorations.Footer
                : string.Empty);
    }

    [Dependency]
    public Decorations Decorations { get; set; }
}

public class ClassA
{
    public void Print(Printer printer, IUnityContainer container)
    {
        container.BuildUp(printer);
        printer.Print("Hello from ClassA");
        container.Teardown(printer);
    }
}

Example using Resolve<T>() :

        var printer = new Printer();

        var containerA = new UnityContainer();
        containerA.RegisterInstance(new Decorations
        {
            Header = "I am HEADER from Decorations #1",
            Footer = "I am FOOTER from Decorations #1"
        });

        var a = new ClassA();

        var objClassA = containerA.Resolve<Decorations>();

and here is example using BuildUp():

        var printer = new Printer();

        var containerA = new UnityContainer();
        containerA.RegisterInstance(new Decorations
        {
            Header = "I am HEADER from Decorations #1",
            Footer = "I am FOOTER from Decorations #1"
        });


        var a = new ClassA();

        var objClassA = containerA.Resolve<Decorations>();

        a.Print(printer, containerA);

score 2 · Answer 1 · answered Dec 22 '15 at 11:52

2

Resolve is used to instantiate an instance of an object, and inject dependencies.

BuildUp is used to inject dependencies into an existing instance of an object.

answered Dec 22 '15 at 11:52

Jamiec

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what i am understanding is `BuildUp()` is for property injection in already instantiated object. Am i right ? – Ehsan Sajjad Dec 22 '15 at 11:55
@EhsanSajjad - not just property injection, I think it will also do method too. – Jamiec Dec 22 '15 at 11:56
what you mean by method injection ? can you elaborate on this? – Ehsan Sajjad Dec 22 '15 at 11:57
You can mark a method to be called on dependency injection, if this takes further dependencies, these will be resolved by the container. More info in the documentation no doubt. – Jamiec Dec 22 '15 at 11:58
can i delete my question as it is already answered here – Ehsan Sajjad Dec 22 '15 at 12:17

Difference between BuildUp and Resolve

1 Answers1