英文:
`R` equivalent to pythons `from src.file import function, class, variable`?
问题
在R中，你可以使用import或importFrom函数从其他脚本中导入所需的对象，而不必使用source()导入整个脚本。这将帮助你避免导入不需要的函数、对象和变量。以下是如何在R中实现类似的功能：
# 在依赖的脚本中使用import或importFrom函数
# 这些函数来自于'roxygen2'包，所以确保你已经安装了该包
#' @importFrom yourPackageName class1 class2
# 或者
#' @import yourPackageName
# 你的脚本内容
setClass("c", slots = c(name = "character"))
# 如果需要从其他脚本中导入类，可以使用import或importFrom函数
在你的脚本中，使用@importFrom标签或@import标签指定你想导入的类或包，而不必使用source()来导入整个脚本。这将使你的代码更模块化，并且不会导入不需要的函数、对象和变量。确保替换yourPackageName为你的R包的名称，以及class1和class2为你想要导入的类的名称。
英文:
I have defined three different S4 classes in their own scripts in my R package. One of those classes uses the other two classes.
I see that devtools::load_all() loads the scripts in alphabetical order, so that if a script depends on another that is later in alphabetical order, there may be problems. Observe:
Example script a.r:
setClass("a", slots = c(name = "character"))
Example script b.r
setClass("b", slots = c(name = "character", a = "a", c = "c"))
Example script c.r:
setClass("c", slots = c(name = "character"))
When I run devtools::load_all(), the following warning appears:
Warning messages:
1: undefined slot classes in definition of "b": c(class "c")
I do not want to rename my scripts simply to put them in alphabetical order based on when I want them to be loaded.
I do not want to define those classes in a single script, because I want to keep the code more modular.
How do I ensure that the script defining the dependent class has access to the other classes:
- Regardless of the names of the scripts those classes are in?
- Without resorting to
source()since this would import other functions, objects, variables, from that script that are not needed.
In python, this is relatively trivial. One uses a syntax like:
from <relative path to .py file that defines those objects> import <desired objects>
In R, I am spinning in circles trying to accomplish something similar.
答案1
得分: 0
我通过深入研究DESCRIPTION文件中的Collate字段找到了一个合适的解决方案。
当我将这部分内容追加到DESCRIPTION文件中时，在运行devtools::load_all()时，警告消息会消失，因为文件将按照我指定的顺序加载，而不是按照字母顺序加载：
Collate:
a.r
c.r
b.r
这并未回答更一般的问题，即如何通过仅导入另一个脚本中定义的特定对象来复制python的行为... load_all()功能似乎仍然会加载脚本中的所有内容，而Collate部分仅指定了顺序... 但我仍然将这视为一种胜利。
英文:
I found a suitable solution by digging into the Collate field in the DESCRIPTION file.
When I append this to the DESCRIPTION file, then the warning goes away when I run devtools::load_all() because files will be loaded in the order I specified rather than alphabetical order:
Collate:
a.r
c.r
b.r
This does not answer the more general question about how to replicate the behavior of python by only importing specific objects defined in another script... The load_all() functionality still seems to load everything in the scripts, and the Collate section simply specifies the order... But I'll still count this as a win.
答案2
得分: -1
鉴于你的 b.r 宏需要 class(c) 被定义，我强烈建议你在 b.r 宏的顶部明确包含 load(c.r) 命令。否则，当有人尝试使用 load(b.r) 而不是 "load.all()" 来设置某些内容时，将会出现故障。始终避免依赖用户执行“额外”的操作。
英文:
Seeing as your b.r macro would like to have class(c) defined, I strongly recommend you explicitly include the command load(c.r) at the top of the b.r macro. Otherwise when someone tries to set up something with load(b.r) rather than "load.all()` there'll be a failure anyway. Always avoid depending on the user executing something "extra" .
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