chain

问题 i have this tsv file containing some paths of links each link is seperated by a ';' i want to use: In the example below we can se that the text in the file is seperated and i only want to read through the last column wich is a path starting with '14th' 6a3701d319fc3754 1297740409 166 14th_century;15th_century;16th_century;Pacific_Ocean;Atlantic_Ocean;Accra;Africa;Atlantic_slave_trade;African_slave_trade NULL 3824310e536af032 1344753412 88 14th_century;Europe;Africa;Atlantic_slave_trade

问题 public void ExecuteProcessChain(string[] asProcesses, string sInRedirect, string sOutRedirect) { Process p1 = new Process(); p1.StartInfo.UseShellExecute = false; p1.StartInfo.RedirectStandardOutput = true; p1.StartInfo.FileName = asProcesses[0]; p1.Start(); StreamReader sr = p1.StandardOutput; string s, xxx = ""; while ((s = sr.ReadLine()) != null) Console.WriteLine("sdfdsfs"); //xxx += s+"\n"; p1.StartInfo.RedirectStandardInput = true; p1.StartInfo.RedirectStandardOutput = false; p1

问题 My question is probably pretty basic but still I can't get a solution in the official doc. I have defined a Celery chain inside my Django application, performing a set of tasks dependent from eanch other: chain( tasks.apply_fetching_decision.s(x, y), tasks.retrieve_public_info.s(z, x, y), tasks.public_adapter.s())() Obviously the second and the third tasks need the output of the parent, that's why I used a chain. Now the question: I need to programmatically revoke the 2nd and the 3rd tasks if

问题 I have code like: obj1 = SomeObject.method1(); if (obj1 != null) { obj2 = obj1.method2(); if (obj2 != null) { obj3 = obj2.method3(); if (obj3 != null) { ............ return objN.methodM(); } } } .... I have near 10 steps. It seems very fragile and error prone. Is there a better way to check on null chained methods? Thanks. 回答1: It's common problem for null references in java. I prefer chaining with && : if (obj1 != null && obj1.method1() != null && obj1.method1().method2() != null) 回答2: More

问题 I'm taking an online class to learn python and the instructor taught us that chain indexing was not a good idea. However, he failed to tell is the appropriate alternative to use. Suppose I have a Pandas data frame with rows indexed as ['1', '2', '3'] and columns with names ['a', 'b', 'c'] . What's the appropriate alternative to using the command df['1']['a'] to extract the value found in the first row and first column? 回答1: Use multi-axis indexing, e.g. df.loc['a', '1'] When you use df['1'][

问题 I'm using Qt and bash over it, need to execute something like: bash: cat file | grep string in Qt: QString cmd = "cat file | grep string"; QProcess *process = new QProcess; process->start(cmd); process->waitForBytesWritten(); process->waitForFinished(); qDebug() << process->readAll(); The problem is in pipe ("|"), and process returs nothing. If there is no ("|"), like "cat file" everything is ok. I tried smth. like "cat file \\| grep string", "cat file \| grep string" but result is the same.

问题 chain.doFilter(req,res); We used this in a servlet program. I want to know what is the use of the method doFilter() in a servlet? Also what is the use of filter and chain concept in Java servlets? 回答1: Servlet filters are implementation of the chain of responsibility pattern The point is that each filter stays "in front" and "behind" each servlet it is mapped to. So if you have a filter around a servlet, you'll have: void doFilter(..) { // do stuff before servlet gets called // invoke the

问题 I know it works, but I don't know why and how. What are the mechanics? // Parent constructor function Parent(name){ this.name = name || "The name property is empty"; } // Child constructor function Child(name){ this.name = name; } // Originaly, the Child "inherit" everything from the Parent, also the name property, but in this case // I shadowing that with the name property in the Child constructor. Child.prototype = new Parent(); // I want to this: if I dont set a name, please inherit "The

问题 In python the following statement returns correct results: >>> 1 == 1 == 1 True >>> 1 == 1 == 0 False Is such construct (or similar) possible in groovy? The following fails: groovy:000> 1 == 1 == 1 ===> false since the first comparison is evaluated to true and true is not equal to 1 . Any workaround on this? 回答1: A workaround would be using AST transformations of course: http://docs.groovy-lang.org/docs/next/html/documentation/core-metaprogramming.html#developing-ast-xforms 回答2: Or if not the

问题 This is a question that spun out of "Rails, how do I chain scopes with an "and" operator between them?". In the accepted answer, the code example generates SQL looking something like: "where 'age' similar to '%(foo|bar)%' AND 'name' similar to '%(foo|bar)%' AND ... and so on. How would I implement this if I want to chain the scopes with OR instead of AND ? 回答1: check the any_of gem. Lets you do things like: banned_users = User.where(banned: true) unconfirmed_users = User.where("confirmed_at