How can I create a more user-friendly string.format syntax?
I need to create a very long string in a program, and have been using String.Format. The problem I am facing is keeping track of all the numbers when you have more than 8-10 parameters.
Is it possible to create some form of overload that will accept a syntax similar to this?
String.Format("You are {age} years old and your last name is {name} ",
{age = "18", name = "Foo"});
How about the following, which works both for anonymous types (the example below), or regular types (domain entities, etc):
static void Main()
{
string s = Format("You are {age} years old and your last name is {name} ",
new {age = 18, name = "Foo"});
}
using:
static readonly Regex rePattern = new Regex(
@"(\{+)([^\}]+)(\}+)", RegexOptions.Compiled);
static string Format(string pattern, object template)
{
if (template == null) throw new ArgumentNullException();
Type type = template.GetType();
var cache = new Dictionary<string, string>();
return rePattern.Replace(pattern, match =>
{
int lCount = match.Groups[1].Value.Length,
rCount = match.Groups[3].Value.Length;
if ((lCount % 2) != (rCount % 2)) throw new InvalidOperationException("Unbalanced braces");
string lBrace = lCount == 1 ? "" : new string('{', lCount / 2),
rBrace = rCount == 1 ? "" : new string('}', rCount / 2);
string key = match.Groups[2].Value, value;
if(lCount % 2 == 0) {
value = key;
} else {
if (!cache.TryGetValue(key, out value))
{
var prop = type.GetProperty(key);
if (prop == null)
{
throw new ArgumentException("Not found: " + key, "pattern");
}
value = Convert.ToString(prop.GetValue(template, null));
cache.Add(key, value);
}
}
return lBrace + value + rBrace;
});
}
As of C#6, this kind of string interpolation is now possible using the new string interpolation syntax:
var formatted = $"You are {age} years old and your last name is {name}";