The evolution of irb does not stop. The most advanced REPL may be Ruby's irb [^ b]. Multi-line editing, syntax highlighting, auto-indentation, and method name completion were shocking.
[^ b]: I am writing without knowing the REPL of other languages, so I welcome Masakari Oshikari, a lover of each language.
Now, with irb 1.2.8 released on December 20, 2020, a feature called measure was added. This measures the time it takes to evaluate the formula.
Displaying the 1 millionth prime number in Ruby
require "prime"
p Prime.lazy.drop(999999).first
Just write. The answer is 15485863. Suppose you want to know how long this will take place. There are many measuring methods, but if you can do it quickly on irb, that's great.
First of all
gem update irb
Let's install the latest irb with. The latest at the time of writing the article (December 23, 2020) is 1.2.9.
And
irb -r prime
Start irb with. No, of course
irb
Start with
irb(main):001:0> require "prime"
It's fine, but it's a hassle, so it's better to pass the library to use to the -r option.
And
irb(main):001:0> measure
If you type, you will be in the mode [^ mode] that measures the evaluation time of the expression ... but in fact, in versions 1.2.8 and 1.2.9, LoadError will appear due to some mistake [^ le]. ]. Fortunately, a pull request to enable the measure command was issued by @elim and has already been captured.
(Added on 2020-12-25) It was reflected in irb 1.3.0 (released on 2020-12-24). Now you can use measure.
[^ mode]: The term "mode" is not used in the original family. I just call it that in this article.
[^ le]: I'm not sure, but this problem seems to occur when installing as a gem. (Added on 2020-12-25) It seems that there is no problem with irb bundled with Ruby 3.0.0.
At present, it can't be helped
irb(main):001:0> IRB.conf[:MEASURE] = true
Let's hit. I can't remember this, but I don't have to. In the next version you should be able to use measure. (→ Addendum: Now)
This way, every time you evaluate an expression on irb, it will measure the time. Now:
irb(main):002:0> Prime.lazy.drop(999999).first
processing time: 7.395823s
=> 15485863
It was about 7.4 seconds.
To stop the measurement mode
irb(main):003:0> IRB.conf[:MEASURE] = false
And.
Once the measure command is available,
irb(main):003:0> measure :off
You should be able to go out.
By the way, there are various things to be careful about in this kind of speed (execution time) measurement.
By default, the measure function of irb seems to only take the time difference before and after processing, so if you measure it when the CPU is busy with other things, a large value will come out. Execution time fluctuates due to various factors. In fact, his 1 millionth prime number was about 6.5 seconds when measured again. (Added on 2020-12-25) Maybe Prime uses memoization, and if you do it again without quitting irb, it will finish in a much shorter time.
Even if the measurement result is 7.395823s, there are not so many significant figures. The only thing that displays a lot of digits is that the Float is displayed as it is.
Well, probably the second decimal place (0.01 digit) doesn't make sense.
So
irb(main):004:0> 1+1
processing time: 0.000282s
=> 2
The number "0.000282s" that comes out is completely meaningless. It can only be called "Hotondo Zero Desnay".
The execution time of such
I haven't tried it, but it seems that the measurement and display processing can be customized. In a file called .irbrc in the user's home directory,
IRB.conf[:MEASURE_PROC][:CUSTOM] = proc { |context, code, line_no, &block|
#And so on
}
It seems that you should describe it with a feeling. This makes it possible, for example, to display the results up to the first decimal place.
See irb's commit message for more details: https://github.com/ruby/irb/commit/3899eaf2e21fcb8b6c1ba3fdb1ac4ec8c9b4798f
Recommended Posts