Allow keywords as property names in components

[snixtho]

Currently if you try to name a property that resembles a C# keyword like "class" or "checked", a syntax error will occur within the template engine.

A potential solution, which keeps the component's interface the same for the users of the component is to prefix variable names with @ behind the scenes when a property is part of a C# keyword. To use the property inside the component, the component author must refer to the component as @Name everywhere.

Example:

<component>
    <property type="string" name="class" /> <!-- define the property like normal, 'class' is a C# keyword -->
    
    <template>
        <label class="{{ @class }}" /> <!-- refer to property 'class' with '@class' -->
    </template>
</component>

Here is a list of all keywords in C#: https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/

The contextual keywords will probably work without any special treatment, but might want to fully test that first. I can see contextual keywords being a problem inside expressions where they are actually available.

[kdankert]

Couldn't we internally use @ nanes and add an @ sign to the variables when we resolve double curly braces?

[snixtho]

Couldn't we internally use @ nanes and add an @ sign to the variables when we resolve double curly braces?

I believe contents within {{ }} is directly evaluated, so that would require a different set up.

[kdankert]

It won't work for expressions. I would suggest limiting variable names to valid c# variable names then, excluding names beginning with underscores as they are used internally already.

[araszka]

We could just substitute reserved keywords with something else like var_class. Then in development it would stay class everywhere but the compiled template would have var_class, so for debugging purposes the dev still knows which variable caused a possible issue.