Python 3.x Python中的未关闭文件警告
我编写了以下代码:Python 3.x Python中的未关闭文件警告,python-3.x,apt,Python 3.x,Apt,我编写了以下代码: class LazyPackageLoader: def __init__(self, package_names): self.package_names = package_names def install_packages(self): try: cache = apt.cache.Cache() cache.update() cache.open
class LazyPackageLoader:
def __init__(self, package_names):
self.package_names = package_names
def install_packages(self):
try:
cache = apt.cache.Cache()
cache.update()
cache.open()
for package in self.package_names:
pkg = cache[package]
pkg.mark_install()
cache.commit()
except Exception as e:
print (str(e))
finally:
cache.close()
def show_all_packages(self):
pkgs = list()
cache = apt.Cache()
for package in cache:
if cache[package.name].is_installed:
pkgs.append(package.name)
cache.close()
return pkgs
我这样称呼它:
class TestLazyPackageLoader(unittest.TestCase):
def test_installed_package(self):
packagelist = list()
packagelist.append("ethtool")
lpl = LazyPackageLoader(packagelist)
lpl.install_packages()
packages = lpl.show_all_packages()
if "ethtool" in packages:
self.assertEqual(True, True)
if __name__ == '__main__':
unittest.main()
代码按预期工作,但我收到以下警告:
ResourceWarning:未关闭的文件缓存.commit
ResourceWarning:未关闭的文件缓存。提交()
我想警告很明显:存在一个未打开的文件,它最终会被Python关闭
我一直在阅读这篇文章,并认为我应该将代码包装在一个“with”语句中,这对于阅读一个简单的文本文件来说很容易,但我不知道如何使用这个库。我认为这里最重要的调用是cache.close
,我认为当最终调用时肯定会执行它。中的快速查找显示apt.cache.cache()
类实现了和关键字所需的两个方法,即\uuuuuuuuuuuu
和退出()
这意味着您只需执行以下操作:
with apt.cache.Cache() as c:
# ... do your things with c ...
# here, c is closed
代码中的一个示例:
def show_all_packages(self):
with apt.cache.Cache() as cache:
return [package.name for package in cache if cache[package.name].is_installed]
我之所以接受这个答案,是因为它回答了我关于用
块将语句包装在中的问题。