From 3364cc45cc5b66dbee37c61c9bfa20ba775f2a5c Mon Sep 17 00:00:00 2001
From: Tatsuyuki Ishi <ishitatsuyuki@gmail.com>
Date: Fri, 17 Dec 2021 10:53:57 +0900
Subject: [PATCH] Allow creating an empty WeakProgressBar

---
 src/progress_bar.rs | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/progress_bar.rs b/src/progress_bar.rs
index e29ed831..38464e22 100644
--- a/src/progress_bar.rs
+++ b/src/progress_bar.rs
@@ -766,12 +766,19 @@ impl MultiProgress {
 /// A weak reference to a `ProgressBar`.
 ///
 /// Useful for creating custom steady tick implementations
-#[derive(Clone)]
+#[derive(Clone, Default)]
 pub struct WeakProgressBar {
     state: Weak<Mutex<ProgressState>>,
 }
 
 impl WeakProgressBar {
+    /// Create a new `WeakProgressBar` that returns `None` when [`upgrade`] is called.
+    ///
+    /// [`upgrade`]: WeakProgressBar::upgrade
+    pub fn new(&self) -> WeakProgressBar {
+        Default::default()
+    }
+
     /// Attempts to upgrade the Weak pointer to a [`ProgressBar`], delaying dropping of the inner
     /// value if successful. Returns `None` if the inner value has since been dropped.
     ///