tpl/lang: Add NumFmt function

[moorereason]

numFormat formats a number with a given precision using the requested decimal,
grouping, and negative characters.

Fixes #1444

[moorereason]

Replaces #1450.

This should be simpler than the previous attempt. Formats the number using strconv and then inserts/replaces characters where needed. Should be easier to maintain.

[bep]

@moorereason if you rebase this, I will merge it. I see many people ask for it, and once we get some aliasing and namespaces in order, I'm not too worried about having "many" funcs. But double check the arg order (and example) so it fits nicely into a pipe.

[moorereason]

Added a pipe example and rebased.

[digitalcraftsman]

Shouldn't the result be -12,345.68

[bep]

While you're in that file, you may also specify what rounding rule used.

[moorereason]

Doh! typo

[moorereason]

Pushed a new commit. Please review.

[moorereason]

@bep, we can merge this after #3415, but I made some changes from my original PR:

• Moved this function to the lang namespace since this is really a localization concern.
• Removed shorthand numFormat from funcMap. Can only access via namespace.
• Renamed from numFormat to NumFmt.

[moorereason]

@bep, this is ready for review.

[bep]

Thinking about this, the signature looks kind of klunky for a template func.

• I kind of want to put the format into my site config, so people can set their own.
• I doubt this will work: myNumFormat = [",", ".", "-"]
• Suspect this will be better and then use strings.Fields: myNumFormat = ", . _"

Other than that it looks fine.

[moorereason]

Good thoughts. How about we build it with the intention that it will work with l10n later. Like i18n, the options are defined in the site config.

func NumFmt(precision int, n float64, opts ...interface{}) string

// Assume that they've defined locale number formatting in the site config.
{{ lang.NumFmt 2 123.456 }}
{{ 123.456 | lang.NumFmt 2 }}

// Given multiple locales defined in config, allow to specify which one to use.
{{ lang.NumFmt 2 123.456 "loc:en_US" }}

// Allow use without a locale definition?
{{ lang.NumFmt 2 123.456 "dec:." "grp:," "neg:-" }}

We don't have to support all of those options, but the func signature would allow us flexibility in the implementation as we move toward l10n.

If we need to think through l10n before merging this, I'm okay with that.

[bep]

We have no concept of locale or "locale formatting". What you are saying is that we should wait until we see how that looks like before we revisit this one.

[bep]

But I think we should just drop the locale debate, and just pack the three arguments into one string. It should be possible to do some magic locale stuff later if needed.

[moorereason]

@bep, how's this look? I still need to add site config support.

[bep]

This looks great. Don't bother with the site config support; we will have to revisit this at some point. With this, people can easily put that config in site params.

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.