CODEWITHSUNDEEP
c#unity-game-engine
Daniel Lip
Daniel Lip

Reputation: 11325

How can i re write the null checking line since it's not supporting in unity?

XDocument document = XDocument.Load(@"C:\Users\mysvg\Documents\my.svg");
            XNamespace ns = "http://www.w3.org/2000/svg";

            var list = document.Root.Descendants(ns + "rect").Select(e => new {
                Style = e.Attribute("style").Value.Substring(15, 7),
                Transform = e.Attribute("transform")?.Value,
                Width = e.Attribute("width").Value,
                Height = e.Attribute("height").Value,
                X = e.Attribute("x").Value
            });

In csharp it's working fine. But in unity visual studio i'm getting error on the line:

e.Attribute("transform")?.Value.Substring(18, 43)

Feature 'null propagating operator' is not available in C# 4. Please use language version 6 or greater.

In csharp i didn't have to change anything.

The visual studio i'm using in unity (same as for csharp) is: 14.0.24531.01 Update 3 and visual c# 2015

Maybe i need to change the line checking for null for something else ?

Upvotes: 0

Views: 456

Answers (2)

Programmer
Programmer

Reputation: 125435

You already know why you can't use ?. and that's because Unity does not support that version of C# that supports ?..

UnholySheep comment suggests using if statement but I don't think you can use that here.

You can check for null with the ternary operator.

Use: 

Transform = e.Attribute("transform") != null ? e.Attribute("transform").Value : "",

If you are still confused. Here is the whole code:

XDocument document = XDocument.Load(@"C:\Users\mysvg\Documents\my.svg");
XNamespace ns = "http://www.w3.org/2000/svg";

var list = document.Root.Descendants(ns + "rect").Select(e => new
{
    Style = e.Attribute("style").Value.Substring(15, 7),
    Transform = e.Attribute("transform") != null ? e.Attribute("transform").Value : "",
    Width = e.Attribute("width").Value,
    Height = e.Attribute("height").Value,
    X = e.Attribute("x").Value
});

Upvotes: 1

rory.ap
rory.ap

Reputation: 35318

You can do it the old fashioned way with a ternary operator ?:, and I'd get the attribute outside the collection initializer so you don't have to index it twice:

var list = document.Root.Descendants(ns + "rect").Select(e => 
    var tr = e.Attribute("transform");

    new {Style = e.Attribute("style").Value.Substring(15, 7),
    Transform = (tr != null) ? tr.Value : null,
    Width = e.Attribute("width").Value,
    Height = e.Attribute("height").Value,
    X = e.Attribute("x").Value
});

If you upgrade your version of Visual Studio to 2015 or 2017, you can use the null conditional operator.

Upvotes: 0

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