Best way to embed data fields in text?

Question

What's the best way to embed data fields in text so they are easily retrievable, and don't affect readability (much)?

For instance, I could do something like "Some instructions here, followed by @firstname:John @lastname:Smith\n", and then write code to parse out the fields. Then I could begin to work out the problems, like embedded @-signs.

But this has been done so many thousands of times, I'm hoping someone can point me to a settled pattern.

Answer 1

Gonna wager a guess based on your question, let me know if I misunderstood...

You'll want to go with something that can easily be picked up by regular expressions and/or variable replacement. It should also be characters you don't use frequently in your text.

Something like "Hello ${firstName} how are you doing today?", or more simply "Hello {0} what's up?"

Some languages have built in support for this, so it depends on your environment.

Answer 2

As Mike said it depends on the environment. In .NET you have "Hello {0}", several languages uses "Hello %s", JavaScript using MooTools uses "Hello {name}" and so on, and so on. Both the "{0}" and "%s" depends on the order of the arguments (which might be a disadvantage).

If you're interested in how to implement it by yourself here is an example using regular expressions in javascript:

// Variables should be an object at the current form:
// {name: 'John', age: 13}
function substitute(string, variables)
{
    var result = string.replace(/\\?\{([^{}]+)\}/g, function(match, name) {
        if(match.charAt(0) == '\\') return match.slice(1); //If there was a backslash before the first {, just return it as it was.
        return (variables[name] != undefined) ? variables[name] : '';
    });
    return result;
}

It shouldn't bee to hard porting to other languages which support regular expressions.

Answer 3

Perhaps a bit of a hack, but if this is just a simple requirement to format some text for a message or internationalisation (etc) you could abuse String.format() (in java, presumably those windows languages have something similar), which takes either a varargs or array parameter like this:

String text = "Hello %s, do you still live at %s?";
String[] replacements = {
    user.name(),
    user.address()
};

String formatted = String.format(text, replacements);

The only problem of course is you cant specify in this the order of the parameters, just where they appear. That may or may not be a problem, but this is probably the quickest solution if it's not.