英文:
golang exercise:images missing at method
问题
我正在解决这个练习：https://tour.golang.org/methods/25 中的图像问题，但是遇到了一个问题。以下是我的代码：
package main
import (
"golang.org/x/tour/pic"
"image"
)
type Image struct{
image *image.RGBA
}
func main() {
rect := image.Rect(0,0,255,255)
myImage := image.NewRGBA(rect)
m := Image{myImage}
pic.ShowImage(m)
}
它给我报错了：
tmp/sandbox089594299/main.go:16: cannot use m (type Image) as type image.Image in argument to pic.ShowImage:
Image does not implement image.Image (missing At method)
但是image.NewRGBA返回的是*NRGBA，而*NRGBA确实有一个At()方法。而且我认为，由于At()方法是image.Image接口所要求的最后一个方法，它应该能找到其他两个必需的方法...那么At()方法出了什么问题呢？
image.NRGBA：https://golang.org/pkg/image/#NRGBA
image.Image接口：https://golang.org/pkg/image/#Image
英文:
I am wokring through the exercise:images at https://tour.golang.org/methods/25 and I have run into a problem. Here is my code...
package main
import (
"golang.org/x/tour/pic"
"image"
)
type Image struct{
image *image.RGBA
}
func main() {
rect := image.Rect(0,0,255,255)
myImage := image.NewRGBA(rect)
m := Image{myImage}
pic.ShowImage(m)
}
it gives me the error...
tmp/sandbox089594299/main.go:16: cannot use m (type Image) as type image.Image in argument to pic.ShowImage:
Image does not implement image.Image (missing At method)
But image.NewRGBA returns a *NRGBA and that does indeed have an At() method. Also I assume since the At() method is the last method required by the image.Image interface then it is finding the other two required methods...so what is up with the At()?
image.NRGBA: https://golang.org/pkg/image/#NRGBA
image.Image interface: https://golang.org/pkg/image/#Image
答案1
得分: 1
你的类型Image没有实现At方法。如果你希望你的类型继承*image.RGBA实现的方法，可以使用匿名字段：
type Image struct {
*image.RGBA
}
参考链接：https://golang.org/doc/effective_go.html#embedding。
英文:
Your type Image does not implement the At method. If you want your type to inherit the methods implemented by *image.RGBA, use an anonymous field:
type Image struct{
*image.RGBA
}
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