1 files changed, 48 insertions, 0 deletions
diff --git a/examples/prompts/history/slow-history.py b/examples/prompts/history/slow-history.py
new file mode 100755
index 0000000..5b6a7a2
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+++ b/examples/prompts/history/slow-history.py
@@ -0,0 +1,48 @@
+#!/usr/bin/env python
+"""
+Simple example of a custom, very slow history, that is loaded asynchronously.
+
+By wrapping it in `ThreadedHistory`, the history will load in the background
+without blocking any user interaction.
+"""
+import time
+
+from prompt_toolkit import PromptSession
+from prompt_toolkit.history import History, ThreadedHistory
+
+
+class SlowHistory(History):
+    """
+    Example class that loads the history very slowly...
+    """
+
+    def load_history_strings(self):
+        for i in range(1000):
+            time.sleep(1)  # Emulate slowness.
+            yield f"item-{i}"
+
+    def store_string(self, string):
+        pass  # Don't store strings.
+
+
+def main():
+    print(
+        "Asynchronous loading of history. Notice that the up-arrow will work "
+        "for as far as the completions are loaded.\n"
+        "Even when the input is accepted, loading will continue in the "
+        "background and when the next prompt is displayed.\n"
+    )
+    our_history = ThreadedHistory(SlowHistory())
+
+    # The history needs to be passed to the `PromptSession`. It can't be passed
+    # to the `prompt` call because only one history can be used during a
+    # session.
+    session = PromptSession(history=our_history)
+
+    while True:
+        text = session.prompt("Say something: ")
+        print("You said: %s" % text)
+
+
+if __name__ == "__main__":
+    main()