added `format_with_items` methods to every types.

src/date.rs

@@ -17,7 +17,7 @@ use naive;
 use naive::date::NaiveDate;
 use naive::time::NaiveTime;
 use datetime::DateTime;
-use format::{DelayedFormat, StrftimeItems};
+use format::{Item, DelayedFormat, StrftimeItems};
 
 /// ISO 8601 calendar date with timezone.
 #[derive(Clone)]
@@ -200,12 +200,18 @@ impl<Off:Offset> Date<Off> {
 }
 
 impl<Off: Offset + fmt::Display> Date<Off> {
-    /// Formats the date in the specified format string.
+    /// Formats the date with the specified formatting items.
+    #[inline]
+    pub fn format_with_items<'a, I>(&'a self, items: I) -> DelayedFormat<'a, I>
+            where I: Iterator<Item=Item<'a>> + Clone {
+        DelayedFormat::new_with_offset(Some(self.local()), None, &self.offset, items)
+    }
+
+    /// Formats the date with the specified format string.
     /// See the `format::strftime` module on the supported escape sequences.
     #[inline]
     pub fn format<'a>(&'a self, fmt: &'a str) -> DelayedFormat<'a, StrftimeItems<'a>> {
-        DelayedFormat::new_with_offset(Some(self.local()), None, &self.offset,
+        self.format_with_items(StrftimeItems::new(fmt))
-                                       StrftimeItems::new(fmt))
     }
 }
 

src/datetime.rs

@@ -16,7 +16,7 @@ use duration::Duration;
 use naive::datetime::NaiveDateTime;
 use time::Time;
 use date::Date;
-use format::{parse, Parsed, ParseResult, DelayedFormat, StrftimeItems};
+use format::{parse, Item, Parsed, ParseResult, DelayedFormat, StrftimeItems};
 
 /// ISO 8601 combined date and time with timezone.
 #[derive(Clone)]
@@ -102,13 +102,19 @@ impl DateTime<FixedOffset> {
 }
 
 impl<Off: Offset + fmt::Display> DateTime<Off> {
-    /// Formats the combined date and time in the specified format string.
+    /// Formats the combined date and time with the specified formatting items.
+    #[inline]
+    pub fn format_with_items<'a, I>(&'a self, items: I) -> DelayedFormat<'a, I>
+            where I: Iterator<Item=Item<'a>> + Clone {
+        let local = self.local();
+        DelayedFormat::new_with_offset(Some(local.date()), Some(local.time()), &self.offset, items)
+    }
+
+    /// Formats the combined date and time with the specified format string.
     /// See the `format::strftime` module on the supported escape sequences.
     #[inline]
     pub fn format<'a>(&'a self, fmt: &'a str) -> DelayedFormat<'a, StrftimeItems<'a>> {
-        let local = self.local();
+        self.format_with_items(StrftimeItems::new(fmt))
-        DelayedFormat::new_with_offset(Some(local.date()), Some(local.time()), &self.offset,
-                                       StrftimeItems::new(fmt))
     }
 }
 

src/naive/date.rs

@@ -15,7 +15,7 @@ use div::div_mod_floor;
 use duration::Duration;
 use naive::time::NaiveTime;
 use naive::datetime::NaiveDateTime;
-use format::{parse, Parsed, ParseResult, DelayedFormat, StrftimeItems};
+use format::{parse, Item, Parsed, ParseResult, DelayedFormat, StrftimeItems};
 
 use self::internals::{DateImpl, Of, Mdf, YearFlags};
 
@@ -366,11 +366,18 @@ impl NaiveDate {
                            Of::new(ordinal, flags))
     }
 
-    /// Formats the date in the specified format string.
+    /// Formats the date with the specified formatting items.
+    #[inline]
+    pub fn format_with_items<'a, I>(&'a self, items: I) -> DelayedFormat<'a, I>
+            where I: Iterator<Item=Item<'a>> + Clone {
+        DelayedFormat::new(Some(self.clone()), None, items)
+    }
+
+    /// Formats the date with the specified format string.
     /// See the `format::strftime` module on the supported escape sequences.
     #[inline]
     pub fn format<'a>(&'a self, fmt: &'a str) -> DelayedFormat<'a, StrftimeItems<'a>> {
-        DelayedFormat::new(Some(self.clone()), None, StrftimeItems::new(fmt))
+        self.format_with_items(StrftimeItems::new(fmt))
     }
 }
 

src/naive/datetime.rs

@@ -15,7 +15,7 @@ use div::div_mod_floor;
 use duration::Duration;
 use naive::time::NaiveTime;
 use naive::date::NaiveDate;
-use format::{parse, Parsed, ParseResult, DelayedFormat, StrftimeItems};
+use format::{parse, Item, Parsed, ParseResult, DelayedFormat, StrftimeItems};
 
 /// ISO 8601 combined date and time without timezone.
 #[derive(PartialEq, Eq, PartialOrd, Ord, Copy, Clone)]
@@ -133,12 +133,18 @@ impl NaiveDateTime {
         Some(NaiveDateTime { date: date, time: time })
     }
 
-    /// Formats the combined date and time in the specified format string.
+    /// Formats the combined date and time with the specified formatting items.
+    #[inline]
+    pub fn format_with_items<'a, I>(&'a self, items: I) -> DelayedFormat<'a, I>
+            where I: Iterator<Item=Item<'a>> + Clone {
+        DelayedFormat::new(Some(self.date.clone()), Some(self.time.clone()), items)
+    }
+
+    /// Formats the combined date and time with the specified format string.
     /// See the `format::strftime` module on the supported escape sequences.
     #[inline]
     pub fn format<'a>(&'a self, fmt: &'a str) -> DelayedFormat<'a, StrftimeItems<'a>> {
-        DelayedFormat::new(Some(self.date.clone()), Some(self.time.clone()),
+        self.format_with_items(StrftimeItems::new(fmt))
-                           StrftimeItems::new(fmt))
     }
 }
 

src/naive/time.rs

@@ -14,7 +14,7 @@ use Timelike;
 use div::div_mod_floor;
 use offset::Offset;
 use duration::Duration;
-use format::{parse, Parsed, ParseResult, DelayedFormat, StrftimeItems};
+use format::{parse, Item, Parsed, ParseResult, DelayedFormat, StrftimeItems};
 
 /// ISO 8601 time without timezone.
 /// Allows for the nanosecond precision and optional leap second representation.
@@ -126,11 +126,18 @@ impl NaiveTime {
         parsed.to_naive_time()
     }
 
-    /// Formats the time in the specified format string.
+    /// Formats the time with the specified formatting items.
+    #[inline]
+    pub fn format_with_items<'a, I>(&'a self, items: I) -> DelayedFormat<'a, I>
+            where I: Iterator<Item=Item<'a>> + Clone {
+        DelayedFormat::new(None, Some(self.clone()), items)
+    }
+
+    /// Formats the time with the specified format string.
     /// See the `format::strftime` module on the supported escape sequences.
     #[inline]
     pub fn format<'a>(&'a self, fmt: &'a str) -> DelayedFormat<'a, StrftimeItems<'a>> {
-        DelayedFormat::new(None, Some(self.clone()), StrftimeItems::new(fmt))
+        self.format_with_items(StrftimeItems::new(fmt))
     }
 
     /// Returns a triple of the hour, minute and second numbers.

src/time.rs

@@ -14,7 +14,7 @@ use Timelike;
 use offset::Offset;
 use duration::Duration;
 use naive::time::NaiveTime;
-use format::{DelayedFormat, StrftimeItems};
+use format::{Item, DelayedFormat, StrftimeItems};
 
 /// ISO 8601 time with timezone.
 #[derive(Clone)]
@@ -51,12 +51,18 @@ impl<Off:Offset> Time<Off> {
 }
 
 impl<Off: Offset + fmt::Display> Time<Off> {
-    /// Formats the time in the specified format string.
+    /// Formats the time with the specified formatting items.
+    #[inline]
+    pub fn format_with_items<'a, I>(&'a self, items: I) -> DelayedFormat<'a, I>
+            where I: Iterator<Item=Item<'a>> + Clone {
+        DelayedFormat::new_with_offset(None, Some(self.local()), &self.offset, items)
+    }
+
+    /// Formats the time with the specified format string.
     /// See the `format::strftime` module on the supported escape sequences.
     #[inline]
     pub fn format<'a>(&'a self, fmt: &'a str) -> DelayedFormat<'a, StrftimeItems<'a>> {
-        DelayedFormat::new_with_offset(None, Some(self.local()), &self.offset,
+        self.format_with_items(StrftimeItems::new(fmt))
-                                       StrftimeItems::new(fmt))
     }
 }