Combining enums and functions

I have found the concept of combining enums with namespaces to be incredibly valuable. For instance, consider the following:

enum Status : {
    OK = 1,
    NOT_OK = 2,
}

namespace Status {

    function Color(status : Status) {

        if(status == Status.OK)
            return 'green';
        else
            return 'red';

    }

}

However, I have come to realize that tslint does not approve of this approach... What alternatives could I explore to achieve similar functionality? One idea I had was to replace the namespace with a class containing static methods, but this presents two challenges:

1) The class would need to have a different name (such as 'StatusUtil') - which is a minor inconvenience.

2) Unlike namespaces, the 'StatusUtil' class cannot be directly accessed from an HTML file in an Angular application - necessitating the inclusion of additional methods in each component, like so:

getColor(status : Status) {
    return StatusUtil(status);
}

Another possibility I considered was leveraging Angular's dependency injection instead of static methods. What approach do you think would be the most effective in this scenario?

Answer №1

In my opinion, this situation presents a compelling argument for ignoring the tslint warning. While tslint serves to alert you to potential issues in your code, it is possible to suppress these warnings with the use of comments within your code.

The rule in question aims to discourage the use of namespaces for organizing code, but there are still circumstances in Typescript where using namespaces is necessary for achieving certain types of merging.

According to weswigham, a member of the Typescript team, in a comment found here:

Is it considered appropriate to merge namespaces with classes, functions, and enums?

Sometimes, it may be justified - especially when specific types of static properties cannot be recognized through ad-hoc attachments. However, in many cases, utilizing ad-hoc properties on a function or class static may be sufficient unless types need to be contained within them. Additionally, it is worth questioning whether the merge was truly necessary in the first place - for instance, if you wish to link a component and its argument type, wouldn't exporting both from the same module be enough? Why enclose them in a namespace as well? There is no benefit in doing so.

The bottom line is:

If you are contemplating using namespaces for code organization: Avoid it. Modules have taken over that role. If you require functionality that only namespaces can offer: Go ahead, but verify that the concept could not be equally expressed without a namespace (for instance, by using a class static or function property, or by re-exporting a module). It is considered poor practice to mix namespaces and modules within the same project as it feels disjointed, given that one of the primary functions of namespaces in the traditional sense is cross-file scope merging, which does not occur across modules (since, as mentioned, the module itself essentially serves as a namespace).

Furthermore, within that discussion, it was confirmed that namespaces will not be phased out from the language, so utilizing them for specific scenarios remains acceptable.

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