Make time.Format localized

[bep]

https://github.com/go-playground/locales

It looks beautifully complete, and has a lot of the stuff that many people ask about, esp. date formatting:

https://github.com/go-playground/locales/blob/master/rules.go#L45

Not sure how to go about with this (esp. considering go-i18n, but I suspect we can take this in 2 round), but one should be able to do something ala:

Week day: {{ site.Language.Translator.WeekDayShort .Date }}

Translator ...?

/cc @jmooring @regisphilibert

[jmooring]

Given date = 2021-02-26T05:22:00-07:00 in frontmatter, I am hopeful that something similar to this would be possible:

Content	Code	Result
post/foo.en.md	{{ .Date.Format "Mon, January 2, 2006"}}	Fri, February 26, 2021
post/foo.es.md	{{ .Date.Format "Mon, January 2, 2006"}}	V, febrero 26, 2021

That's just a translation of two strings, and I'm not really sure how helpful it would be. Perhaps a better example would be:

Content	Code	Result
post/foo.en.md	{{ .Date.Localize.Long }}	Friday, February 26, 2021
post/foo.es.md	{{ .Date.Localize.Long }}	el viernes 26 de febrero de 2021

[regisphilibert]

I think it's great to wrap this in .Date.Localize so we can have: .Date.Localize.MonthAbbreviated, .Date.Localize.MonthWide etc...

Though I think we'll have to document what those wordings means (WeekdayNarrow, WeekdayShort, WeekdayWide etc...) I couldn't find any examples in the two links shared in this thread.

I educated myself: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat/DateTimeFormat

[jmooring]

@regisphilibert

Examples:
https://github.com/go-playground/locales/blob/master/en_US/en_US.go#L61-L74

[bep]

post/foo.es.md | {{ .Date.Localize.Long }} | el viernes 26 de febrero de 2021

What if I want to list the Spanish posts on the English site?

[regisphilibert]

What if I want to list the Spanish posts on the English site?

It's an edge case and you should work for it :)

People will need to understand that .Date.Localize is a page method and as such it relies on the page's data to find the proper language to use.

But we could also introduce a way to create a localized date. Maybe timeLocalized which would take a second parameter for the language:

{{ $EsDate := timeLocalized (now.Unix) "es" }}
hoy dia: {{ $EsDate.Weekday.Long }}

[jmooring]

@bep You are making my head hurt.

[bep]

It's an edge case and you should work for it :)

You, maybe, but why should I work for it.

Week day: {{ site.Language.Translator.WeekDayShort .Date }}

The above would solve it for all cases without any magic. And it's much simpler to implement and also more efficient.

[regisphilibert]

Now, I do have a few questions, number 3 being the most important (You can find them better formatted on the page shared above)

As you I mean the users who want to print spanish content on their english pages.

I can live with you suggestion and it does improve the way people have dealt with localized date before (data file + i18n) but you will still have to work with several methods to build one date.

A simple example to write: Tuesday: February 4 2021 in engish and Mardi: 3 février 2006 in french (I'm not even considering the 2nd, 3rd issue.

<time datetime="{{ .Date.Format "2006-01-02T15:04:05-0700" }}">
{{ if eq site.Language.Lang "fr" }}
 {{ site.Language.Translator.WeekDayLong .Date }}: {{ .Date.Format "2" }} {{ site.Language.Translator.MonthWide .Date }}  {{ .Date.Year }}
{{ else }}
{{ .Date.Format "Monday: January 2 2006  }}
</time>

I guess what most users would be thrilled about is an easy way to print a localized date similar to .Date.Format without the gymnastic illustrated above.

[bep]

We could try to make a site.Language.Translator.FormatDate method that works the same as time.Format.

[bep]

Or we could do {{ time.Format .Date "Monday: January 2 2006" }}.

[regisphilibert]

It's all in the perspective of UX/DX.

If you're working with english date you can rely on the page .Date object which sports its own .Format but if using another language, you should use site.Language.Translator.FormatDate .Date.

Which means theme creators will need to use systematically that translator method on the site.Language which seems a bit remote. As people are used to using .Date.Format from the page context and dateFormat from the rest, I wonder how we can introduce something similar or even the same with an optional third argument for the language code.

[bep]

@regisphilibert I'm scoping down this particular issue into making time.Format (which we already have, which also supports a string input) localized.