runtime | 易学教程

bases doesn't work! What's next?

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问题 The following code doesn't work in Python 3.x, but it used to work with old-style classes: class Extender: def extension(self): print("Some work...") class Base: pass Base.__bases__ += (Extender,) Base().extension() Question is simple: How can I add dynamically (at runtime) a super class to a class in Python 3.x? But I'm ready the answer will be hard! ) 回答1: As for me it is impossible. But you can create new class dynamically: class Extender(object): def extension(self): print("Some work...")

Why is it so slow iterating over a big std::list?

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问题 As title suggests, I had problems with a program of mine where I used a std::list as a stack and also to iterate over all elements of the list. The program was taking way too long when the lists became very big. Does anyone have a good explanation for this? Is it some stack/cache behavior? (Solved the problem by changing the lists to std::vector and std::deque (an amazing data structure by the way) and everything suddenly went so much faster) EDIT: I'm not a fool and I don't access elements

Can Perl be “statically” parsed?

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问题 An article called "Perl cannot be parsed, a formal proof" is doing the rounds. So, does Perl decide the meaning of its parsed code at "run-time" or "compile-time"? In some discussions I've read, I get the impression the arguments stem from imprecise terminology, so please try to define your technical terms in your answer. I have deliberately not defined "run-time", "statically" or "parsed" so that I can get perspectives from people who perhaps define those terms differently to me. Edit: This

Build parser from grammar at runtime

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问题 Many (most) regular expression libraries for C++ allow for creating the expression from a string during runtime. Is anyone aware of any C++ parser generators that allow for feeding a grammar (preferably BNF) represented as a string into a generator at runtime? All the implementations I've found either require an explicit code generator to be run or require the grammar to be expressed via clever template meta-programming. 回答1: It should be pretty easy to build a recursive descent, backtracking

If statement weirdness in Visual Studio 2008

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问题 I've come across a problem so strange, that I've recorded my session because I didn't think anyone would belive me. I came across a bug that seems to be at very fundamental level. This is a single threaded application and all im doing is evaluating a boolean. The boolean equals false, however, the if statement is executing as if it were true...sort of. You'll see what I mean. I've cleaned the solution and rebuilt many times. No idea whats going on. I'd love some explanations please. http:/

Load package dynamically

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问题 Is it possible to load a specific package during runtime? I want to have a kind of plugins where each one has the same functions than the others but with different behaviour, and depending on the configuration file, load one or other. 回答1: You might consider executing the ‘plugin’ packages at runtime, by writing out a new program (say, to a temp directory) and executing via exec.Command, something along the lines of exec.Command("go", "run", files…).Run() You’ll see some similar code here.

linux安装openjdk1.8

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1、使用yum查找jdk yum search java|grep jdk [root@node1 ~]# yum search java|grep jdk ldapjdk-javadoc.noarch : Javadoc for ldapjdk java-1.6.0-openjdk.x86_64 : OpenJDK Runtime Environment java-1.6.0-openjdk-demo.x86_64 : OpenJDK Demos java-1.6.0-openjdk-devel.x86_64 : OpenJDK Development Environment java-1.6.0-openjdk-javadoc.x86_64 : OpenJDK API Documentation java-1.6.0-openjdk-src.x86_64 : OpenJDK Source Bundle java-1.7.0-openjdk.x86_64 : OpenJDK Runtime Environment java-1.7.0-openjdk-accessibility.x86_64 : OpenJDK accessibility connector java-1.7.0-openjdk-demo.x86_64 : OpenJDK Demos java-1.7.0

Understanding the “underlying C/C++ object has been deleted” error

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问题 It's not the first time I am getting the RuntimeError: underlying C/C++ object has been deleted . I've solved it many times altering my code in a random but intuitive way but now I am facing this again and just don't understand why it happens... What I ask for is a generic approach to confront and solve this error. I will not post code samples here because my project is too complex and I just can't figure out where's the bug. And also because I am asking for the universal solution not just

how can I debug a jar at runtime?

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问题 I'm into a quite strange position (from my java-newbie point of view): using Eclipse I wrote a "java program" (some .java files with classes into) which essentially (batch) reads a text *.csv file, "evaluates" its contents, and writes out results into an *_out.csv text file. To locate the input file it uses a "file chooser" (got sample from here: http://docs.oracle.com/javase/tutorial/uiswing/components/filechooser.html) I debugged all the code and, using the debugger, it works . I ran the

run a Java program in specific time

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问题 i need help to run my Java program on the server at a specific time like 2 pm (to index the new files). Someone told me that Java has some thing called jobs but I don't know how to work with that. I tried this: boolean cond=true; while(cond){ @SuppressWarnings("deprecation") int heur = new Date().getHours(); @SuppressWarnings("deprecation") int minute= new Date().getMinutes(); if(heur==16 && minute==02){ indexer.close(); end = new Date().getTime(); File f; cond=false; } But with this the