如果没有arg，则针对stdin运行脚本；否则输入文件= ARGV [0] [英] Script to run against stdin if no arg; otherwise input file =ARGV[0]

问题描述

这很好用-只是想知道是否有任何改进可以缩短它?

This works quite nicely - just wondered if there are any improvements to shorten it ?

if (ARGV[0].nil?) then
    input=$<
else
    input=File.new(ARGV[0],"r");
end

...
# Do something with the input here, for example:
input.each_line do |line|
    puts line
end

推荐答案

您可以完全消除前五行.

You can eliminate the first five lines entirely.

来自镐头

$< ;:提供访问以下内容的对象 内容的串联 以命令行形式给出的所有文件 参数或$ stdin(如果 没有参数). $<支持 与File对象类似的方法: binmode，close，closed ?，每个， each_byte，each_line，eof，eof ?、文件， 文件名，fileno，getc，gets，lineno， lineno =，路径，pos，pos =，读取， readchar，readline，readlines，倒带， 搜寻，跳过，告诉，to_a，to_i，to_io， to_s，以及中的方法 可数.方法文件返回一个 当前文件的文件对象 被阅读.这可能会更改为$< 读取命令上的文件 线. [r/o]

$<: An object that provides access to the concatenation of the contents of all the files given as command-line arguments or $stdin (in the case where there are no arguments). $< supports methods similar to a File object: binmode, close, closed?, each, each_byte, each_line, eof, eof?, file, filename, fileno, getc, gets, lineno, lineno=, path, pos, pos=, read, readchar, readline, readlines, rewind, seek, skip, tell, to_a, to_i, to_io, to_s, along with the methods in Enumerable. The method file returns a File object for the file currently being read. This may change as $< reads through the files on the command line. [r/o]

因此:

print $<.read

Kernel.gets是$&.; gets的简写，所以:

Kernel.gets is shorthand for $<.gets, so:

while s = gets
  puts s
end

这篇关于如果没有arg，则针对stdin运行脚本；否则输入文件= ARGV [0]的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！