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This seems to work.

knoppix@Microknoppix:~$ perl -E ' > @l = qw{ a bb c d e f g h }; > say sub { join q{ }, @_ }->( > grep defined, map shift @l, 1 .. 3 > ) while @l;' a bb c d e f g h knoppix@Microknoppix:~$

I also piped the output through hexdump to check that there were no trailing spaces (which you do get without the grep).

Update: Using List::Util::min() to remove the need for the grep.

knoppix@Microknoppix:~$ perl -MList::Util=min -E ' > @l = qw{ a bb c d e f g h }; > say sub { join q{ }, @_ }->( > map shift @l, 1 .. min( 3, scalar @l ) > ) while @l;' a bb c d e f g h knoppix@Microknoppix:~$

Cheers,

JohnGG


In reply to Re: Rosetta code: Split an array into chunks by johngg
in thread Rosetta code: Split an array into chunks by eyepopslikeamosquito

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    [Corion]: erix: Yeah, I just found that it has no documentation at all on how to circumvent/ eliminate "1+n SELECTs" by building a local hash... I guess I have to make ->has_many do the hash lookup instead of doing the SQL query. But as the problem ...
    [Corion]: ... has only manifested itself so far through the puzzled questions of other bystanders, I won't go deeper at this time. But the DBIx::Class documentation could well do with a document on how to make "it" (that is, ORMs in general) faster ;)
    [Corion]: I find that DBIx::Class, like most ORMs makes things easy until they become performance critical and then makes it horribly hard to change things because the design is highly inflexible if you don't already know about the problems of 1+n :-/
    [choroba]: that's why I don't like similar libraries. They pretend you don't have to learn SQL, but in the end, you have to learn how SQL plus to overcome their own limitations
    [Corion]: "Just write the proper SQL beforehand" is of course the appropriate solution, but if you did that, you wouldn't/couldn't use DBIx::Class either. At least not in an obvious (to me) way.
    choroba scratches a "how"
    [Corion]: choroba: Exactly... But maybe that's just because I'm old and grumpy ;)
    [Corion]: But maybe that could also be a nice talk, how to restructure your DBIx::Class-based app to remove 1+n-style query patterns
    [Corion]: In theory, that should be easy because you should have the "where" clause from part 1 of the patterns and then do the corresponding single select using that where clause to select all rows in one go for the n other parts.
    [Corion]: But in practice I don't see any obvious places documented in DBIx::Class where one would do that and then just feed hash lookups instead of DB lookups for ->has_many results

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