Repeat argument N times?

Repeat argument N times?

[Benjamin R. Haskell]

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Is there a built-in way to repeat an argument N times?

Brace expansion is something I fall back on too much, so I've gotten in the
habit of using it for small values of N, e.g. with a script I use to test
uploading files to a web app:

    upload-files file1{,,} file2{,}{,,,,} file3{,,,}

uploads 3 copies of file1, 10 copies of file2, and 4 copies of file3.

It'd be nice if I could write (something like):

    upload-files file1(N3) file2(N10) file3(N4)

Today I found myself writing:

    upload-files file1{,}{,,,,}{,}{,,,,}

And while it's nice to know I can factor 100, it'd be nicer to just write
it.

-- 
Best,
Ben

Re: Repeat argument N times?

[Bart Schaefer]

On Jul 29, 11:12pm, Benjamin R. Haskell wrote:
} 
} Is there a built-in way to repeat an argument N times?

Not really.  You have to admit it's a rather unusual thing to do.  It
can be done by abusing other expansions, as you've discovered.
 
} It'd be nice if I could write (something like):
} 
}     upload-files file1(N3) file2(N10) file3(N4)

You can create an array of N empty elements just by assigning to the
Nth position:

    N[100]=()

And then:

    upload-files file1$^N[1,3] file2$^N[1,10] file3$^N[1,4]

Works up to however much memory you're willing to waste on allocating
empty array slots.

There are other ways, e.g.

    upload-files file2${^${:-{1..10}}/*/}

    upload-files file2(e{'repeat 10 reply+=($REPLY)'})

though the latter requires "file2" to actually exist, which sometimes
might be a good thing.

Re: Repeat argument N times?

[Peter Stephenson]

On Tue, 29 Jul 2014 23:48:30 -0700
Bart Schaefer <schaefer@brasslantern.com> wrote:
> There are other ways, e.g.
> 
>     upload-files file2(e{'repeat 10 reply+=($REPLY)'})
> 
> though the latter requires "file2" to actually exist, which sometimes
> might be a good thing.

If you don't mind a limited repertoire of counts explicitly constructed,
you can make this method look close to what you want.

% define-x() { eval "x$1() { typeset -ga reply; repeat $1 reply+=(\$REPLY) }" }
% define-x 3
% print .zshrc(+x3)
.zshrc .zshrc .zshrc

pws

Re: Repeat argument N times?

[Roman Neuhauser]

# p.stephenson@samsung.com / 2014-07-30 09:56:57 +0100:
> On Tue, 29 Jul 2014 23:48:30 -0700
> Bart Schaefer <schaefer@brasslantern.com> wrote:
> > There are other ways, e.g.
> > 
> >     upload-files file2(e{'repeat 10 reply+=($REPLY)'})
> > 
> > though the latter requires "file2" to actually exist, which sometimes
> > might be a good thing.
> 
> If you don't mind a limited repertoire of counts explicitly constructed,
> you can make this method look close to what you want.
> 
> % define-x() { eval "x$1() { typeset -ga reply; repeat $1 reply+=(\$REPLY) }" }
> % define-x 3
> % print .zshrc(+x3)
> .zshrc .zshrc .zshrc

it looks like the alternative syntax permits generalization:

  function x
  {
    typeset -ga reply
    repeat $1 do
      reply+=($REPLY)
    done
  }

  print :)(e:x 3:)
  print :)(e:x 30:)

-- 
roman

Re: Repeat argument N times?

[Roman Neuhauser]

# neuhauser@sigpipe.cz / 2014-07-30 16:10:31 +0200:
>   print :)(e:x 3:)
>   print :)(e:x 30:)

s/:)/.zshrc/ ...

-- 
roman

Re: Repeat argument N times?

[Mikael Magnusson]

On 30 July 2014 08:48, Bart Schaefer <schaefer@brasslantern.com> wrote:
> On Jul 29, 11:12pm, Benjamin R. Haskell wrote:
> }
> } Is there a built-in way to repeat an argument N times?
>
> Not really.  You have to admit it's a rather unusual thing to do.  It
> can be done by abusing other expansions, as you've discovered.
>
> } It'd be nice if I could write (something like):
> }
> }     upload-files file1(N3) file2(N10) file3(N4)
>
> You can create an array of N empty elements just by assigning to the
> Nth position:
>
>     N[100]=()
>
> And then:
>
>     upload-files file1$^N[1,3] file2$^N[1,10] file3$^N[1,4]
>
> Works up to however much memory you're willing to waste on allocating
> empty array slots.
>
> There are other ways, e.g.
>
>     upload-files file2${^${:-{1..10}}/*/}
>
>     upload-files file2(e{'repeat 10 reply+=($REPLY)'})
>
> though the latter requires "file2" to actually exist, which sometimes
> might be a good thing.

Here's another minor variation on the first one,
upload-files file1${(s: :)^${(l:50:)}}

-- 
Mikael Magnusson