Added the ability to create a value from a function (#121)

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 All notable changes to MiniJinja are documented here.
 
+# Unreleased
+
+- Added `Value::from_function`.
+
 # 0.22.1
 
 - Fixed an incorrect manifest for `minijinja-autoreload`.

minijinja/src/environment.rs

@@ -413,7 +413,7 @@ impl<'source> Environment<'source> {
         Rv: FunctionResult,
         Args: for<'a> FunctionArgs<'a>,
     {
-        self.add_global(name, functions::BoxedFunction::new(f).to_value());
+        self.add_global(name, Value::from_function(f))
     }
 
     /// Adds a global variable.

minijinja/src/value/mod.rs

@@ -78,6 +78,7 @@ use std::sync::Arc;
 use serde::ser::{Serialize, Serializer};
 
 use crate::error::{Error, ErrorKind};
+use crate::functions;
 use crate::key::{Key, StaticKey};
 use crate::utils::OnDrop;
 use crate::value::serialize::ValueSerializer;
@@ -370,6 +371,18 @@ impl Value {
         Value::from_rc_object(Arc::new(value))
     }
 
+    /// Creates a callable value from a function.
+    pub fn from_function<F, Rv, Args>(f: F) -> Value
+    where
+        // the crazy bounds here exist to enable borrowing in closures
+        F: functions::Function<Rv, Args>
+            + for<'a> functions::Function<Rv, <Args as FunctionArgs<'a>>::Output>,
+        Rv: FunctionResult,
+        Args: for<'a> FunctionArgs<'a>,
+    {
+        functions::BoxedFunction::new(f).to_value()
+    }
+
     /// Returns some reference to the boxed object if it is of type `T`, or None if it isn’t.
     ///
     /// This is basically the "reverse" of [`from_object`](Self::from_object).