ruby – 如果没有arg则运行stdin的脚本;否则输入文件= ARGV [0]

这很好用 – 只是想知道是否有任何改进来缩短它？

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

解决方法

你可以完全消除前五行.

来自Pickaxe

$<: 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：

while s = gets
  puts s
end