Question

我希望除了* args之外还使用一个required_arg，来自另一个类的一个类中的** kwargs。但目前我没有成功！这段代码：

class PageNumCanvas(canvas.Canvas):
    "For  add \"page number of total\" in each footer."

    def __init__(self, page1, *args, **kwargs):
        "Constructor."
        self.page1 = page1 - 1
        canvas.Canvas.__init__(self, *args, **kwargs)
        self.pages = []

我这样做的错误消息：canvasmaker = PageNumCanvas(1)：

canvas.Canvas.__init__(self, *args, **kwargs)
    TypeError: __init__() takes at least 2 arguments (1 given)

如何使用page1参数调用PageNumCanvas类？

更新＃1：

如果我不在类的 init 中使用参数，我没有问题。例如：

>>> from reportlab.pdfgen import canvas
>>> class PageNumCanvas(canvas.Canvas):
...     "For  add \"page number of total\" in each footer."
...     def __init__(self, *args, **kwargs):
...             canvas.Canvas.__init__(self, *args, **kwargs)
...             self.pages = []
... 
>>> canvasmaker = PageNumCanvas(1)
>>> canvasmaker
<__main__.PageNumCanvas instance at 0x7f618195df38>
>>>

更新＃2：感谢goncalopp提供的方法，正确的代码是：

class PageNumCanvas(canvas.Canvas):
...     "For  add \"page number of total\" in each footer."
...     def __init__(self, page1, *args, **kwargs):
...             "Constructor."
...             canvas.Canvas.__init__(self, page1, *args, **kwargs)
...             self.page1 = page1 - 1
...             self.pages = []
...             print self.page1
... 
>>> canvasmaker = PageNumCanvas(12)
11
>>>

Answer 1

你可能正在寻找

canvas.Canvas.__init__(self, page1, *args, **kwargs)

Answer 2

在示例here中，您需要在实例化canvas.Canvas()时提供名称。

你的第二个版本没有给你一个错误的原因是你仍然传递1传递给Canvas构造函数，因为你删除了page1参数。 / p>

为了使其有效，您只需传递一个名称和页码：

from reportlab.pdfgen import canvas
class PageNumCanvas(canvas.Canvas):
    "For  add \"page number of total\" in each footer."

    def __init__(self, page1, *args, **kwargs):
        "Constructor."
        self.page1 = page1 - 1
        canvas.Canvas.__init__(self, *args, **kwargs)
        self.pages = []

canvasmaker = PageNumCanvas(1, "Hello.pdf")
print canvasmaker.page1

<强>输出

使用required_arg，* args，** kwargs的类定义

2 个答案: