Lapp and bug about penlight

[stevedonovan]

(Embarassed cat face). Because it seems that -h is hardwired to mean 'help'! Easy for me to fix however; if a person defines '-h' (or '--help') then don't use the default handling.

[Atcold]

LoL, ok it was an end of the day bug (tiredness doesn't help debugging).. And, in an older program of mine, I was already using such -h for the --height contraction and therefore I couldn't understand why it wasn't working and no error or warning was thrown up.
Tnx for the prompt feedback!

One further question: would it make sense to use multi-characters contractions? For example -s for --save and -sk for -seek? This is because I've plenty of scripts that uses multi-characters shorteners and I'd like to keep some kind of back compatibility even if I'm cleaning up the code.

[stevedonovan]

The problem with -sk is that a common interpretation is that this is short for -s -k. We can have an option to disable this behaviour for a particular flag (or all flags) but then people might be confused?

[Atcold]

No, you're right, but if I'm writing

-sk,--seek (number) Seconds to seek

then there wouldn't be any confusion, right? As long as I define it myself I wouldn't get confused. But maybe I'm asking you too much..

[stevedonovan]

I'm more worried about users getting confused. But then, there are many standards for command line args (some use single hyphen for long flags as well). So I should not be too fascist and impose GNU-style on all my users. Let me have a look at what's involved...

[Atcold]

He, he, he, you're fun to speak with! Now it's 04:30 and I'm laughing instead of sleeping. LoL But I guess if you state clearly you care about GNU compatibly, then who's going to use your tools will automatically accept the thing. So, don't waste your time listening to me and having the -h not forced to --help is more than enough!!

[stevedonovan]

Ah, it turned out to be easy - but you do have to use 'slack' mode ;)

-- alfredo.lua
require 'pl'
lapp.slack = true
args = lapp [[
Does some calculations
   -vs,--video-set              (string)             Use the German road sign dataset
   -w,--width              (default 256)        Width of the video
   -h,--height             (default 144)        Height of the video
   -t,--time               (default 10)         Seconds of video to process
   -sk,--seek               (default 0)          Seek number of seconds
   -dbg                   Debug!
   ]]

pretty.dump(args)

Call like so:

D:\dev\lua\Penlight\scratch>lua alfredo.lua -vs 200 -sk 1
{
  video_set = "200",
  time = 10,
  height = 144,
  seek = 1,
  dbg = false,
  width = 256
}

[Atcold]

Great! Thank you @stevedonovan! Everything's fine but the pretty.dump(args). Lua tells me pretty is undefined (a nil value).

[stevedonovan]

That's strange! With the example as typed (using require 'pl' to make the submodules all available) it shows no such error. What system are you using?

[Atcold]

Ok, I mess up again, and I was using your local configuration (local lapp = require 'pl.lapp')...
Anyhow, I am using Torch and.. for printing tables I just use print(args).
So, this code

-- Plotting the parsed commands ------------------------------------------------
print 'args ='
print(args)
pretty = require 'pl.pretty'
pretty.dump(args)

gives me

that is quite nicer 😉