Question

我想在类中实现延迟加载的属性。我认为这很容易并且像这样实现：

 <com.google.android.flexbox.FlexboxLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:flexWrap="nowrap"
        app:alignItems="stretch"
        app:alignContent="stretch" >

        <TextView
            android:id="@+id/textview1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="#ff0"
            android:text="niledfdfdfhfgfdgdfgdfgfgfggdfgdfggggggggggggggggggggggggggggggggggggggggggggggfhssdsdsdsfgdfgfgfgfgfggfgdgdfgfgfgdsddjfhdkjfhjshdf"            />

        <TextView
            android:id="@+id/textview2"
            android:layout_width="wrap_content"
            android:text="nilxcvxceshdfhd"
            android:background="@color/colorAccent"
            android:layout_height="wrap_content"
            app:layout_minWidth="50dp"
            app:layout_minHeight="20dp"
            app:layout_alignSelf="center"

            />

    </com.google.android.flexbox.FlexboxLayout>

但是现在我很惊讶，在 init 之后_bar变量包含了longTimeLoadedData甚至Foo.bar从未被调用过......有人可以向我解释这个行为吗？提前谢谢！

Answer 1

看起来它已经像你想要的那样工作了：

class Foo:
    def __init__(self):
        self._bar = None

    @property
    def bar(self):
        if not self._bar:
            self._bar = 1
        return self._bar


f = Foo()

print(f._bar) # None
f.bar
print(f._bar) # 1

延迟加载属性，@ property decorator

1 个答案: