Idea: Inline includes?

[shazow]

In Python-land, it's not uncommon to include subsections of an INI file from another INI file. (Especially in Paste-style INI files.)

So I could have

# development.ini
[app]
database = "sqlite://whatevs.db"
# [... lots of other things]

And in my unit testing environment, I'd override just one key...

# testing.ini
[app]
use = config:development.ini#app
database = "sqlite:///:memory:"

TOML proposal

As for how this would look like in TOML if we wanted to support it, perhaps some variation of...

# Assign to section?
[app] = development.ini#app
database = "override value"

Or perhaps...

# Non-assignments are treated as includes?
[app]
development.ini#app
database = "override value"

# Could even support multiple includes
[app]
app_defaults.ini
development.ini#app
somekey = "foo"
someotherkey = "bar"
override_keys.ini#app

Quite possibly out of scope for TOML, but an interesting thought experiment.

[robn]

Then you have a runtime requirement. Bad. If you want includes, use some specially-named key that has meaning for your application, and sort it out yourself.

include = [ "foo.ini", "bar.ini", "baz.ini" ]

[mojombo]

@shazow It's a cool idea, but you're right, I think it's outside the scope of TOML. @robn's solution is a decent one, I think.

[shazow]

Agreed all around.

[Artoria2e5]

I am definitely not proposing to add this to TOML, but just for a better format in case someone wants to do a little dialect:

In TOML the unquoted keys can only be alphanumeric or -_ (see unquoted-key in ABNF). This leaves us a lot of space to expand using the symbols, so we can have:

%include "foo.toml"
%include-dir "conf.d"

... which could be described more concretely as:

preprocessor = %x25 preprocessor-key ws string
preprocessor-key = "include" / "include-dir"

I am calling it "preprocessor" as integrating this stuff into the expression tree is not something I want to look at at all, although for the top level you can just go with expression =/ preprocessor.

And this clearly lacks the flexibility to just include a part of some other file -- you should probably hack up a variant of JSONPath for that and handle it in the application after all. (Yeah, nothing stops you from putting that in the percent-PP-statement too, but doing so would bring about even more cursed changes as you begin to put it in the core syntax.)

[dgutson]

What happened to this feature, why was closed? %include was very cool!

[pradyunsg]

See the closing note: #36 (comment)