mutable

问题 I want to have immutable Java objects like this (strongly simplified): class Immutable { protected String name; public Immutable(String name) { this.name = name; } public String getName() { return name; } } In some cases the object should not only be readable but mutable, so I could add mutability through inheritance: public class Mutable extends Immutable { public Mutable(String name) { super(name); } public void setName(String name) { super.name = name; } } While this is technically fine, I

问题 I have been playing around with dataclasses dynamically loaded with property names from a file and I am unable to find a way to create both 'frozen' and 'non-frozen' properties. I believe dataclasses only allow you to set all properites to frozen or non-frozen. As of now, I create a frozen dataclass and add a mutable class as one of the properties which I can change as I go but I am not very happy with the readability of this approach. Is there another pythonic dataclass people would

问题 I have been playing around with dataclasses dynamically loaded with property names from a file and I am unable to find a way to create both 'frozen' and 'non-frozen' properties. I believe dataclasses only allow you to set all properites to frozen or non-frozen. As of now, I create a frozen dataclass and add a mutable class as one of the properties which I can change as I go but I am not very happy with the readability of this approach. Is there another pythonic dataclass people would

问题 Example code： fn main() { let a = [1, 2, 3, 4, 5]; reset(a); } fn reset(mut b: [u32; 5]) { b[0] = 5; } The variable a is an immutable array, and the reset function's parameter b is a mutable array; intuitively I need to modify a to a mutable array before I can call the reset method, but the compiler tells me that I don't need to do this, why is this? fn main() { let mut a = [1, 2, 3, 4, 5]; reset(a); } fn reset(mut b: [u32; 5]) { b[0] = 5; } warning: variable does not need to be mutable -->

问题 I am very familiar with C/C++ standard function declarations. I've recently seen something like this: int myfunction(char parameter) const The above is only a hypothetical example and I don't even know if it makes sense. I'm referring to the part AFTER the parameter. The const. What is this? A more real example: wxGridCellCoordsArray GetSelectedCells() const This can be found here So what exactly is that text const doing at the end of the line? 回答1: The const keyword, when shown after a

问题 I am very familiar with C/C++ standard function declarations. I've recently seen something like this: int myfunction(char parameter) const The above is only a hypothetical example and I don't even know if it makes sense. I'm referring to the part AFTER the parameter. The const. What is this? A more real example: wxGridCellCoordsArray GetSelectedCells() const This can be found here So what exactly is that text const doing at the end of the line? 回答1: The const keyword, when shown after a

问题 I am very familiar with C/C++ standard function declarations. I've recently seen something like this: int myfunction(char parameter) const The above is only a hypothetical example and I don't even know if it makes sense. I'm referring to the part AFTER the parameter. The const. What is this? A more real example: wxGridCellCoordsArray GetSelectedCells() const This can be found here So what exactly is that text const doing at the end of the line? 回答1: The const keyword, when shown after a

问题 I'm relatively new to Python and have problems with immutable variables. I'm trying to change the value of a class attribute (e.g. car.color). The difficulty is, that I can not use the namespace of car for doing this. Up to now I did not find a satisvying answer to my questions. In the code below I tried to summarize the possible solutions (workarrounds) I found and their disadvantages: class Car: def __init__(self): self.color = "green" self.color_list = ["green"] self.color_attrib = "green"

问题 I had this: let alphaPtr = UnsafeMutablePointer<vImagePixelCount>(mutating: alpha) as UnsafeMutablePointer<vImagePixelCount>? Which now I get the warning: Initialization of 'UnsafeMutablePointer' (aka 'UnsafeMutablePointer') results in a dangling pointer Detailed warning consists of: Implicit argument conversion from '[vImagePixelCount]' (aka 'Array') to 'UnsafePointer' (aka 'UnsafePointer') produces a pointer valid only for the duration of the call to 'init(mutating:)' Use the

问题 I had this: let alphaPtr = UnsafeMutablePointer<vImagePixelCount>(mutating: alpha) as UnsafeMutablePointer<vImagePixelCount>? Which now I get the warning: Initialization of 'UnsafeMutablePointer' (aka 'UnsafeMutablePointer') results in a dangling pointer Detailed warning consists of: Implicit argument conversion from '[vImagePixelCount]' (aka 'Array') to 'UnsafePointer' (aka 'UnsafePointer') produces a pointer valid only for the duration of the call to 'init(mutating:)' Use the