Kevin Walzer wrote:
I'm an experienced developer in several other languages (Python, Tcl,
AppleScript, JavaScript, C/Objective C), so I'm quite familiar with
structuring a program--but as I work on learning Perl, I find it
somewhat obscure, if not downright obfuscated. None of the other
languages I've worked with have the equivalent of the $_ implicit var,
for instance. Looking at some sample code online, I had to spend a
considerable amount of time looking up the various bits with sigils and
annotating them, cf:
open (INPUT, "< $_"); ##input from default $_ var
It is very bad to use a system function like open() without determining
if it succeeded or failed. Also, most modern Perl programmers use the
three argument version of open() and lexical filehandles.
open my $INPUT, '<', $_ or die "Cannot open '$_' because: $!";
Also, the File::Find::find() function callback function, which this code
is part of, only allows you to access the current file name through the
$_ variable, while in other contexts a lexical variable can be used
instead of $_.
foreach (<INPUT>) {
A foreach loop operates on a list so perl has to read the entire file
into a list in memory. This is usually written with a while loop which
only reads one line at a time.
while (<INPUT>) {
if(/$searchstring/i) { ##case-insenstive regex for $searchstring
Case-insenstive regex for the contents of $searchstring. A match
operator does interpolation basically the same as a double quoted
string. A better way would be to create $searchstring using the qr//
operator with the /i option.
$_ = substr($_, 0, 60); ##trim string to 60 chars
That is an inefficient way to truncate a string. A better way would be:
substr( $_, 60 ) = ''; ##trim string to 60 chars
Or perhaps better:
substr( $_, 60, length(), '' ); ##trim string to 60 chars
As this modifies the string in-place.
s/^\s*//; #trim leading space
That modifies every string, whether it contains leading whitespace or
not. It should be written to only modify strings that actually contain
whitespace:
s/^\s+//; #trim leading space
print "$File::Find::name\:$.\:\t$_\n"; #print filename followed by line
number followed by tab followed by matching line
The $. (current line number) variable only contains useful information
from inside a while loop but does nothing useful from inside a foreach loop.
}
}
close INPUT;
Perhaps this is idiomatic to you,
No, it is not. It looks like someone who doesn't understand Perl wrote
this. You should be careful what you download off the internet. ;)
but it's very dense to me. And I have
a decade of development experience.
John
--
Any intelligent fool can make things bigger and
more complex... It takes a touch of genius -
and a lot of courage to move in the opposite
direction. -- Albert Einstein
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