Re: Trimming arrays
- Original Message
From: Patrick R. Michaud pmich...@pobox.com
I would expect this to be roughly equivalent to:
for @array { $_ .= trim; }
For an array of hashes, this would result in each hash element
of @array being replaced with a reference to an array of the
trimmed string representation of the hash.
Oops -- I over-referenced here. The corrected form:
For C @array».=trim , each element of @array would be replaced
with its trimmed string representation. If @array starts out
as an array of hashes, then @array».=trim would leave @array
with the trimmed stringification of each hash element.
I don't get this. If I can't call @array.trim, I certainly can't call
%hash.trim. If you mean stringify the hash and then trim *that*, what does
that mean? We get that all the time in Perl 5 and I've written tests to catch
things like HASH(0x80631d0) showing up in templates. This is probably some of
the most useless behavior in Perl 5 and I don't want to see it propagate to
Perl 6. Either that should die violently or it should do something useful and
I'm unsure of what would be useful here.
A hash is basically a set of pairs. You *can't* trim the keys because they're
supposed to be unique. Otherwise, what does it mean to trim { ' foo' = 1,
'foo ' = 2 }? So we can only trim values, but what if the values are pairs?
Then wouldn't you effectively be apply the hyperop recursively throughout the
data structure? That might be expensive and have unwanted side-effects (what
do you mean my hash had a reference to your ORM data?).
Cheers,
Ovid
--
Buy the book - http://www.oreilly.com/catalog/perlhks/
Tech blog- http://use.perl.org/~Ovid/journal/
Twitter - http://twitter.com/OvidPerl
Official Perl 6 Wiki - http://www.perlfoundation.org/perl6
Re: Trimming arrays
On Wed, Jan 14, 2009 at 03:37:57AM -0800, Ovid wrote: - Original Message From: Patrick R. Michaud pmich...@pobox.com Oops -- I over-referenced here. The corrected form: For C @array».=trim , each element of @array would be replaced with its trimmed string representation. If @array starts out as an array of hashes, then @array».=trim would leave @array with the trimmed stringification of each hash element. I don't get this. If I can't call @array.trim, I certainly can't call %hash.trim. If you mean stringify the hash and then trim *that*, what does that mean? You _can_ call @array.trim -- it returns the trimmed value of the stringified value of the array. Arrays stringify to all of their elements separated by a space (if the element doesn't already end with some kind of space, although Rakudo doesn't implement that part yet). Stringifying a hash in Perl 6 produces a string with keys and values separated by tab characters, and each pair terminated by a newline. See Synopsis 2, beginning with In order to interpolate an entire hash... Pm
Re: Trimming arrays
* Ovid publiustemp-perl6langua...@yahoo.com [2009-01-13 00:35]: * Larry Wall la...@wall.org [2009-01-13 00:25]: It should probably say No such method. We have hyperops now to apply scalar operators to composite values explicitly: @array».=trim Won't that fail with 'No such method' on an array of hashes? Or are hyperops applied recursively? I would *NOT* want a simple `».` to recurse down into a data structure. But I wonder if it’s reasonable to expect that hypermethodcalls will collect their return values in an array. Then trimming the values of the hashes in an array would be simply @array».values».=trim; Imagine writing this in another language. Regards, -- Aristotle Pagaltzis // http://plasmasturm.org/
Re: Trimming arrays
On Mon, Jan 12, 2009 at 03:30:05PM -0800, Ovid wrote:
From: Larry Wall la...@wall.org
: my @array = ' foo ', ' bar ';
: @array .= trim;
: say @array.perl;
:
: And what if I have an array of hashes of hashes of arrays?
:
: Currently you can call 'trim' on arrays, but it's a no-op.
: Similar issues with chomp and friends.
It should probably say No such method.
S29 doesn't document .trim, but like other similar methods I
would expect it to be defined on CAny. If so, I would
expect the output of the above to be C [foo bar]\n .
We have hyperops now to apply
scalar operators to composite values explicitly:
@array».=trim
Won't that fail with 'No such method' on an array of hashes?
Or are hyperops applied recursively?
I would expect this to be roughly equivalent to:
for @array { $_ .= trim; }
For an array of hashes, this would result in each hash element
of @array being replaced with a reference to an array of the
trimmed string representation of the hash.
Pm
Re: Trimming arrays
Ovid wrote:
What should this output?
my @array = ' foo ', ' bar ';
@array .= trim;
say @array.perl;
And what if I have an array of hashes of hashes of arrays?
Currently you can call 'trim' on arrays, but it's a no-op. Similar issues
with chomp and friends.
I think calling a Str method on an Array should force the array to
stringify, then call that method.
If you want to call it on each item, you can use @array.map: { .=trim };
or maybe @array».=trim
Cheers,
Moritz
Re: Trimming arrays
On Tue, Jan 13, 2009 at 08:19:25AM -0600, Patrick R. Michaud wrote:
@array».=trim
Won't that fail with 'No such method' on an array of hashes?
Or are hyperops applied recursively?
I would expect this to be roughly equivalent to:
for @array { $_ .= trim; }
For an array of hashes, this would result in each hash element
of @array being replaced with a reference to an array of the
trimmed string representation of the hash.
Oops -- I over-referenced here. The corrected form:
For C @array».=trim , each element of @array would be replaced
with its trimmed string representation. If @array starts out
as an array of hashes, then @array».=trim would leave @array
with the trimmed stringification of each hash element.
Pm
Re: Trimming arrays
On Mon, Jan 12, 2009 at 03:05:21PM -0800, Ovid wrote: : What should this output? : : my @array = ' foo ', ' bar '; : @array .= trim; : : say @array.perl; : : And what if I have an array of hashes of hashes of arrays? : : Currently you can call 'trim' on arrays, but it's a no-op. Similar issues with chomp and friends. It should probably say No such method. We have hyperops now to apply scalar operators to composite values explicitly: @array».=trim Larry
Re: Trimming arrays
- Original Message From: Larry Wall la...@wall.org : my @array = ' foo ', ' bar '; : @array .= trim; : : say @array.perl; : : And what if I have an array of hashes of hashes of arrays? : : Currently you can call 'trim' on arrays, but it's a no-op. Similar issues with chomp and friends. It should probably say No such method. We have hyperops now to apply scalar operators to composite values explicitly: @array».=trim Won't that fail with 'No such method' on an array of hashes? Or are hyperops applied recursively? Cheers, Ovid -- Buy the book - http://www.oreilly.com/catalog/perlhks/ Tech blog- http://use.perl.org/~Ovid/journal/ Twitter - http://twitter.com/OvidPerl Official Perl 6 Wiki - http://www.perlfoundation.org/perl6
