[API Proposal]: string.ToTitleCase() extension method(s)

[SteveDesmond-ca]

Background and motivation

I often find myself needing to title case strings, and the current API for doing so isn't so intuitive. As the action is being performed on the string, it seems more idiomatic for a .ToTitleCase() method to happen on the string itself.

API Proposal

public static class StringExtensions
{
    public static string ToTitleCase(this string str) => CultureInfo.CurrentCulture.TextInfo.ToTitleCase(str);
    public static string ToTitleCase(this string str, CultureInfo culture) => culture.TextInfo.ToTitleCase(str);
}

API Usage

var bookName = "a tale of two cities";
var title = bookName.ToTitleCase();

var eh = new CultureInfo("en-CA");
var songName = "my favourite chords";
var title = songName.ToTitleCase(eh);

Alternative Designs

This could also be done as a single method with an optional culture parameter:

public static string ToTitleCase(this string str, CultureInfo? culture = null)
    => (culture ?? CultureInfo.CurrentCulture).TextInfo.ToTitleCase(str);

but I think the overload is probably a better choice, and aligns more with existing .NET API designs.

The method could also be called .ToTitle() to better align with .ToUpper() and ToLower(). This may also involve adding a .ToTitleInvariant() variant for consistency.

Risks

There's a chance that using the current culture as the default leads to undesired results based on incorrect developer assumptions, which may not be present when explicitly choosing a CultureInfo/TextInfo. I think this is a similar risk to how time zones are dealt with: certain actions use the host's current time zone by default.

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Issue Details

---

Background and motivation

I often find myself needing to title case strings, and the current API for doing so isn't so intuitive. As the action is being performed on the string, it seems more idiomatic for a .ToTitleCase() method to happen on the string itself.

API Proposal

public static class StringExtensions
{
    public static string ToTitleCase(this string str) => CultureInfo.CurrentCulture.TextInfo.ToTitleCase(str);
    public static string ToTitleCase(this string str, CultureInfo culture) => culture.TextInfo.ToTitleCase(str);
}

API Usage

var bookName = "a tale of two cities";
var title = bookName.ToTitleCase();

var eh = new CultureInfo("en-CA");
var songName = "my favourite chords";
var title = songName.ToTitleCase(eh);

Alternative Designs

This could also be done as a single method with an optional culture parameter:

public static string ToTitleCase(this string str, CultureInfo? culture = null)
    => (culture ?? CultureInfo.CurrentCulture).TextInfo.ToTitleCase(str);

but I think the overload is probably a better choice, and aligns more with existing .NET API designs.

The method could also be called .ToTitle() to better align with .ToUpper() and ToLower(). This may also involve adding .ToTitleInvariant() variants.

Risks

There's a chance that using the current culture as the default leads to undesired results based on incorrect developer assumptions, which may not be present when explicitly choosing a CultureInfo/TextInfo. I think this is a similar risk to how time zones are dealt with: certain actions use the host's current time zone by default.

Author:	SteveDesmond-ca
Assignees:	-
Labels:	api-suggestion, area-System.Globalization, untriaged
Milestone:	-

[filipnavara]

. NET relies on ICU to do the case conversions. There is an API to title case a string but you would likely be disappointed with the result if default options are used. Neither the Unicode standard nor the CLDR have data for the stop words, so for lord of the flies you would get Lord Of The Flies instead of Lord of the Flies.

Since there are no standard data with the stop words you would likely need to expose a more advanced API where the user can supply a list.

[SteveDesmond-ca]

How does the current TextInfo.ToTitleCase() handle it? This is really just syntactic sugar on top of that. Or are you saying (similar to the "Risks" section above) that there are different implications/assumptions if ToTitleCase() is called on a string?

[filipnavara]

How does the current TextInfo.ToTitleCase() handle it? This is really just syntactic sugar on top of that.

My bad, I didn't see that on mobile (the right part of the code block was a hidden). It doesn't handle stop words, you get "Lord Of The Flies". So if the ask is just syntactic sugar for that I guess it's fine (although it may run against the goals in dotnet/designs#207).

[SteveDesmond-ca]

Yeah, we can tweak this so it better aligns with dotnet/designs#207 as well

[tarekgh]

@SteveDesmond-ca this kind nice to have a feature but nobody requested that for long time which can tell there is not much demand for it. Also, as @filipnavara, we are trying to not expose more things inside string class that can have implicit linguistic behavior. It is proven this causes a lot of pain and we are already in the process of working to enhance this experience. I suggest closing this issue as the workaround is easy and the proposal does not match the direction we want to go with.

I suggest closing this issue if that makes sense to you. Thanks for your report.

CC @GrabYourPitchforks

This issue has been marked needs-author-action and may be missing some important information.

[SteveDesmond-ca]

OK, I'll reconsider once dotnet/designs#207 has been implemented. At the very least, now there's an official record that this functionality is desired in some capacity!