Tag Helpers: Ignore '@' symbols in Tag Helper attributes if not string or character.

[NTaylorMullen]

The typical flow for a Razor developer is to write @Foo when they want to switch from HTML to C# code. Now that we're dealing with HTML attributes that could potentially be projected into a C# context we need to consider the impact.

Do we ignore @ symbols in C# projected HTML attributes?

AKA:

public class CurrentAgeTagHelper : TagHelper
{
    public int Age { get; set; }
    ...
}

@{
    myAge = "3";
}

<currentAge age="@myAge" />
<currentAge age="myAge" /> @* This has equivalent output to the line above *@
<currentAge age="3" /> @* This has equivalent output to the line above *@

[DamianEdwards]

Right now, I'm thinking we make them all equivalent. The alternative seems odd to me and just unnatural given we know what the developer means here.

[yishaigalatzer]

If we do nothing here, the code will just not compile.
the generated code will look something like that:

Razor => { int thevariable = 3 } <MyTag class="@thevariable" />
C# generated code => int thevariable =3; context.AddAttribute("class", Write(thevariable))

Doug thinks this should actually generate

int thevariable = 3; tagHelper.class = @thevariable;

Another thing to discuss is that passthrough just doesn't work in this case for class="foo @bar" when @bar evaluated to false or null, spaces are being removed and cleanedup, which prevents pass through

[bar]

@yishaigalatzer hi, you should stop using my handle for that :p

[yishaigalatzer]

@bar that's very true. I'll make sure not to use foo either :)

[bar]

@yishaigalatzer beware... foo has bad temper! haha