specifications

问题 In Python, class variables can be accessed via that class instance: >>> class A(object): ... x = 4 ... >>> a = A() >>> a.x 4 It's easy to show that a.x is really resolved to A.x , not copied to an instance during construction: >>> A.x = 5 >>> a.x 5 Despite the fact that this behavior is well known and widely used, I couldn't find any definitive documentation covering it. The closest I could find in Python docs was the section on classes: class MyClass: """A simple example class""" i = 12345

问题 There are some chapters in the CSS spec mentioning "propagated to the viewport"; for example: calculating the height. This section also applies to block-level non-replaced elements in normal flow when 'overflow' does not compute to 'visible' but has been propagated to the viewport. What kind of attribute can propagate? And does it contradict with the rule in which a child element inherits an attribute from its parent? 回答1: As the quote states, the overflow property is capable of being

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: JSON: why are forward slashes escaped? json.org states, that forward slashes (aka solidus, / ) can be escaped: "\/" However, unescaped slashes are valid, too: "/" What's the rational behind this? Does it come from the Javascript roots? (I.e., "</script>" is a problem in browser-based Javascript, see Douglas Crockford's comment) Or has it any other reason? 回答1: I've just published a review of this issue on my

问题 This code: class B { protected: void Foo(){} } class D : public B { public: void Baz() { Foo(); } void Bar() { printf("%x\n", &B::Foo); } } gives this error: t.cpp: In member function 'void D::Bar()': Line 3: error: 'void B::Foo()' is protected Why can I call a protected method but not take its address? Is there a way to mark something fully accessible from derived classes rather than only accessible from derived classes and in relation to said derived class? BTW: This looks related but what

问题 In all of the create info structs ( vk*CreateInfo ) in the new Vulkan API, there is ALWAYS a .sType member. Why is this there if the value can only be one thing? Also the Vulkan specification is very explicit that you can only use vk*CreateInfo structs as parameters for their corresponding vkCreate* function. It seems a little redundant. I can see that if the driver was passing this struct straight to the GPU, you might need to have it (I did notice it is always the first member). But this

问题 In the nuspec versioning docs I see 1.0 = 1.0 ≤ x (,1.0] = x ≤ 1.0 (,1.0) = x < 1.0 [1.0] = x == 1.0 (1.0) = invalid (1.0,) = 1.0 < x (1.0,2.0) = 1.0 < x < 2.0 [1.0,2.0] = 1.0 ≤ x ≤ 2.0 empty = latest version. I have a packages.config that looks like this <packages> <package id="psake" version="4.2.0.1" /> </packages> and I would like to change the version to "latest". I've tried both <packages> <package id="psake" version="" /> </packages> and <packages> <package id="psake" /> </packages>

问题 I am using rSpec for testing my application. In my application controller I have a method like so: def set_current_account @current_account ||= Account.find_by_subdomain(request.subdomains.first) end Is it possible to set the request.subdomain in my spec? Maybe in the before block? I am new to rSpec so any advice on this would be great thanks. Eef 回答1: I figured out how to sort this issue. In my before block in my specs I simply added: before(:each) do @request.host = "#{mock_subdomain}

问题 I am using rSpec for testing my application. In my application controller I have a method like so: def set_current_account @current_account ||= Account.find_by_subdomain(request.subdomains.first) end Is it possible to set the request.subdomain in my spec? Maybe in the before block? I am new to rSpec so any advice on this would be great thanks. Eef 回答1: I figured out how to sort this issue. In my before block in my specs I simply added: before(:each) do @request.host = "#{mock_subdomain}

问题 Why is <form enctype=multipart/form-data> required when uploading a file to a web-server? 回答1: It has to do with how the browser packages binary and form data for transmission over HTTP. By default only form data is sent, but if the form needs to support uploading a file, then the binary data must also be appended and separated from the form data. Scott Hanselman gives a good explanation of this here: HTTP and How File Upload works via HTTP It's always better, for me, to understand WHY and

问题 I have install sample.rpm in /opt. I want samplw2.rpm find the relocation path of sample.rpm ad install itself in same place. is there any command or macro in spec file which check it befor installation or not? 回答1: I'm pretty sure this isn't possible; the file locations are fixed. The easiest solution would be to put them in a known location, and then set up a symlink in your %post , e.g. linking /opt/sample2 to /usr/local/sample2 where the latter is where the RPM puts the files. 来源： https:/