新手问题 新手关于 Ruby 的一个疑问
File.open "/Users/lic/Desktop/3.txt" do |f|
f.each_line do |line|
puts line
end
end
如上代码，我并没有在 File.open 方法中发现 yidle 关键字，为什么可以在这里直接用代码块呢？ 见笑了，请大神指点
因为是用 C 写的？你可以试试在命令行运行下面代码
$ gem install pry-doc
$ irb
require 'pry'
binding.pry
show-source File#open
#1 楼 @although13 正解。
[3] pry(main)> show-source File#open
From: io.c (C Method):
Owner: Kernel
Visibility: private
Number of lines: 36
static VALUE
rb_f_open(int argc, VALUE *argv)
{
ID to_open = 0;
int redirect = FALSE;
if (argc >= 1) {
CONST_ID(to_open, "to_open");
if (rb_respond_to(argv[0], to_open)) {
redirect = TRUE;
}
else {
VALUE tmp = argv[0];
FilePathValue(tmp);
if (NIL_P(tmp)) {
redirect = TRUE;
}
else {
VALUE cmd = check_pipe_command(tmp);
if (!NIL_P(cmd)) {
argv[0] = cmd;
return rb_io_s_popen(argc, argv, rb_cIO);
}
}
}
}
if (redirect) {
VALUE io = rb_funcall2(argv[0], to_open, argc-1, argv+1);
if (rb_block_given_p()) {
return rb_ensure(rb_yield, io, io_close, io);
}
return io;
}
return rb_io_s_open(argc, argv, rb_cFile);
}