ros::Subscriber sub = n.subscribe("chatter", 1000, chatterCallback); /** * ros::spin() will enter a loop, pumping callbacks. With this version, all * callbacks will be called from within this thread (the main on
11. Iterate Over Root Path Write a Python program to iterate over a root level path and print all its sub-directories and files, as well as loop over specified dirs and files. Click me to see the sample solution 12. Path Existence and Split Write a Python program to test whether a giv...
pyenv shell <version> -- select just for current shell session pyenv local <version> -- automatically select whenever you are in the current directory (or its subdirectories) pyenv global <version> -- select globally for your user account...
表2-6 中 C# 的例子可能看起来有些复杂。正在讨论的结构,for-loop,是一种古老的技术,由现在将要讨论的几个元素组成。 头部(即从的开始的部分)包含关于主体(即由花括号包围的部分)将被执行多少次的指令。在我们的示例中,头部分如下所示: 定义一个辅助数值变量i并赋予i零值(int I = 0;). 只要变量i小于三...
This is a useful idiom: pass a generator to the list() function, and it will iterate through the entire generator (just like the for loop) and return a list of all the values. The for loop will automatically call the next() function to get values from the generator and assign them to...
This will immediately recurse through the directory tree and add watches on all subdirectories. New directories will automatically have watches added for them and deleted directories will be cleaned-up. The other differences from the standard functionality: You can't remove a watch since watches are...
The huge advantage of the latter is that, with a single change to a setting on the logger instance, you can either show or hide all your debugging messages. This means you no longer have to go through the process of commenting and uncommenting your print() statements in order to show ...
In Python, the flow of code is almost entirely controlled through code indentation (see Fig. 1.3). These signifies which blocks of code belong to which flow statements. To break out of a loop, therefore, all that is needed is to revert the code back inline with the previous block of ...
template: Function with a Simple Loop As small as Example 4-3 is, it demonstrates all the usual parts of functions containing a while statement. def fn(): initialize values while test values: use values change values # repeat return result Example 4-4 shows the same function as Example 4...
Files within the directory can reference other files within the same directory, or even within subdirectories. (More on that in a minute.) But the entire collection of files is presented to other Python code as a single module — as if all the functions and classes were in a single .py...