import streamlit as st

@st.cache_resource
def get_database_session(url):
    # Create a database session object that points to the URL.
    return session

s1 = get_database_session(SESSION_URL_1)
# Actually executes the function, since this is the first time it was
# encountered.

s2 = get_database_session(SESSION_URL_1)
# Does not execute the function. Instead, returns its previously computed
# value. This means that now the connection object in s1 is the same as in s2.

s3 = get_database_session(SESSION_URL_2)
# This is a different URL, so the function executes.

默认情况下，cache_resource函数的所有参数都必须是可哈希的。 任何以_开头的参数都不会被哈希。您可以将此用作不可哈希参数的“逃生舱口”：

import streamlit as st

@st.cache_resource
def get_database_session(_sessionmaker, url):
    # Create a database connection object that points to the URL.
    return connection

s1 = get_database_session(create_sessionmaker(), DATA_URL_1)
# Actually executes the function, since this is the first time it was
# encountered.

s2 = get_database_session(create_sessionmaker(), DATA_URL_1)
# Does not execute the function. Instead, returns its previously computed
# value - even though the _sessionmaker parameter was different
# in both calls.

cache_resource 函数的缓存可以通过程序清除：

import streamlit as st

@st.cache_resource
def get_database_session(_sessionmaker, url):
    # Create a database connection object that points to the URL.
    return connection

fetch_and_clean_data.clear(_sessionmaker, "https://streamlit.io/")
# Clear the cached entry for the arguments provided.

get_database_session.clear()
# Clear all cached entries for this function.

要覆盖默认的哈希行为，可以传递一个自定义的哈希函数。 你可以通过将一个类型（例如Person）映射到一个哈希 函数（str）来实现，如下所示：

import streamlit as st
from pydantic import BaseModel

class Person(BaseModel):
    name: str

@st.cache_resource(hash_funcs={Person: str})
def get_person_name(person: Person):
    return person.name

或者，您可以将类型的完全限定名称（例如 "__main__.Person"）映射到哈希函数：

import streamlit as st
from pydantic import BaseModel

class Person(BaseModel):
    name: str

@st.cache_resource(hash_funcs={"__main__.Person": str})
def get_person_name(person: Person):
    return person.name

import streamlit as st
import time

@st.cache_data
def foo(bar):
    time.sleep(2)
    st.write(f"Executed foo({bar}).")
    return bar

if st.button("Clear all cached values for `foo`", on_click=foo.clear):
    foo.clear()

if st.button("Clear the cached value of `foo(1)`"):
    foo.clear(1)

foo(1)
foo(2)