Macros

[keats]

Macros

[Keats]

@SergioBenitez @andrelmartins if you are interested.

I'll try to implement that soon since I think it's the last big feature missing but I'm moving continents next week so will be a bit busy for a while.

[andrelmartins]

Here's an alternative syntax suggestion.

Import

An alternative to allowing per macro renames, would be to require namespace naming. I think this aligns better with the per-file namespacing and avoids having to rename a lot of macros, at the expense of a more verbose call site (see below). Of course, it would be an error to have more than one import with the same namespace name in the same template file.

Short form (naming required):
{% import "macros.html" as macros %}

Long form:
{% import "macros.html" as mymacros : macro1, macro2 %}

Or, alternatively, using the "from" syntax:
{% from "macros.html" as mymacros import * %}
{% from "macros.html" as mymacros import macro1, macro2 %}

Macro use

At the call site, it would be required to prefix the macro name with the namespace:
{{ mymacros::macro1(arg1, arg2) }}

Alternatives

A slight variant would be to allow one to omit the namespace naming and then macros from that import would fall into a "root" namespace and not require the namespace prefix for macro use. That complicates the code a bit more and re-introduces a more limited version of macro name collision. I would lean towards requiring namespace naming.

Extra features

A more pie in the sky feature would be to allow registering Rust functions as macros. Something like this:

let mymacros = MacroSet::new();

mymacros.add(args1, func1);
mymacros.add(args2, func2);

tera.import_macros(mymacros);

where "args1" would be a list of context names and the add function would be something like:

pub fn add<F>(&mut self, args: Vec<String>, usermacro: F)
    where F: Send + Sync + 'static + Fn(&Context) -> TeraResult<String>

[Keats]

I like the short form, not so much the others (if i import something by name, I don't want to have to prefix it). Only having the short form should solve most (all?) of the naming collisions.

I'm curious if @mitsuhiko has some insight on that or some things he would like to change from Jinja2