Beefy Boxes and Bandwidth Generously Provided by pair Networks
"be consistent"
 
PerlMonks  

Re: understanding closures

by enriirne (Initiate)
on Sep 27, 2005 at 14:50 UTC ( [id://495398]=note: print w/replies, xml ) Need Help??


in reply to understanding closures

A little piece of code which uses two closures, partial application and a higher order function. The poor perl code reflects my few weeks on this language.
# getRowsLazy :: DB_Handle -> (String -> String -> ()) -> (SQLQuery -> + {':parm1' => value, ...} -> [[DBType, ..., DBType]]) # Closure on $dbh, lazy version and partial application on the first t +wo params # # ex: my $dbh = ...DBI connect... my $getRows = F::getRowsLazy($dbh, sub { myErrFun($[0], $[1], $M +Y_FUN_NAME, $MY_TRACE_LEVEL) } ); # ... # my $iter = $getRows->("select * from device_param where ID=:id", + {':id' => 123456}); # while (my $row = $iter->()) { # print $row->[0] . ", " . $row->[1] . "\n"; # } # sub F::getRowsLazy { my ($dbh, $errFun); return sub { my ($sql,$p) = @_; my $sth = $dbh->prepare($sql) || $errFun->("Error in DBI::prepare" +, $dbh->errstr() ); while (my ($k,$v) = each(%$p)) {$sth->bind_param($k, $v);} $sth->execute() || $errFun->("Error in DBI::execute", $dbh->errstr +() ); my $yield = sub { my $row = $sth->fetchrow_arrayref; if ($row) {return $row;} $sth->finish(); return undef; }; return $yield; # the call to $yield->() returns a referenc +e; doesn't work with array, but I don't know way } };

Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Node Status?
node history
Node Type: note [id://495398]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others making s'mores by the fire in the courtyard of the Monastery: (4)
As of 2024-03-29 08:09 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found