basarat/typescript-book

TIP Strongly typed names

basarat opened this issue · 5 comments

getName : https://github.com/TypeStrong/atom-typescript/blob/master/lib/main/lang/utils.ts#L300-L308

var nameExtractorRegex = /return (.*);/;
/** Get the name using a lambda so that you don't have magic strings */
export function getName(nameLambda: () => any) {
    var m = nameExtractorRegex.exec(nameLambda + "");
    if (m == null)
        throw new Error("The function does not contain a statement matching 'return variableName;'");
    var access = m[1].split('.');
    return access[access.length - 1];
}

David's function : http://stackoverflow.com/a/32542368/390330

function getPropertyName(propertyFunction) {
    return /\.([^\.;]+);?\s*\}$/.exec(propertyFunction.toString())[1];
}

Handy! Thanks :)

The one from the TS compiler doesn't always work after running through the fairly simple ASP.Net bundling & minification as it can strip the ';' off the end of the generated function's return statement. By that I mean you get
function(){return x.something}
rather than
function(){ return x.something; }
and the ';' makes all the difference

I've slightly tweaked it for my use now, with some brief smoke tests

    var nameExtractorRegex = /return (.*);/;
    var nameExtractorRegexNoTrailingSemi = /return (.*)/;
    /** Get the name using a lambda so that you don't have magic strings */
    export function getName(nameLambda: (o?:any) => any) {
        var m = nameExtractorRegex.exec(nameLambda + "");
        if (m == null) {
            m = nameExtractorRegexNoTrailingSemi.exec(nameLambda + "");
            if (m == null) {
                throw new Error("The function does not contain a statement matching 'return variableName'");
            }
        }
        var access = m[1].split('.');        
        var name = access[access.length - 1];

        //prevent trailing whitespace, '}'
        while (name[name.length - 1] === '}' || name[name.length - 1] === ' ') {
            name = name.substr(0, name.length - 1);
        }

        return name;
    }

You can do const nameExtractorRegex = /return (.*);?/; to say that ; is optional but still not a part of the capture group 🌹

Yes that's a better approach 👍
I'll update my code later and report back if I have issues.

My RegEx foo leaves a lot to be desired