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in reply to Help with code optimization

G'day hyu968,

One thing that immediately leapt out at me was this block of code: 

    if($data=~m/^\s*FORM\s*TYPE:\s*(.*$)/m) {$form_type=$1;}
    if($data=~m/^\s*CENTRAL\s*INDEX\s*KEY:\s*(\d*)/m) {$cik=$1;}
    if($data=~m/^\s*CONFORMED\s*PERIOD\s*OF\s*REPORT:\s*(\d*)/m) {$rep
+ort_date=$1;}
    if($data=~m/^\s*FILED\s*AS\s*OF\s*DATE:\s*(\d*)/m) {$file_date=$1;
+}
    #if($data=~m/^\s*SEC\s*FILE\s*NUMBER:\s*([0-9-]*)/m) {$file_number
+=$1;}
    if($data=~m/^\s*COMPANY\s*CONFORMED\s*NAME:\s*(.*$)/m) {$name=$1;}
    if($data=~m/^\s*STANDARD\s*INDUSTRIAL\s*CLASSIFICATION:.*?\[(\d{4}
+)/m) {$sic=$1;}

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Each of those conditions is mutually exclusive: once you have a match, all the remaining conditions will be FALSE. So you could change all but the first if to elsif, use one of the forms shown in perlsyn - Basic BLOCKs, or use something like this: 

for ($data) {
    /^\s*FORM .../ and do { $whatever = $1; last };
    /^\s*CENTRAL .../ and do { $whatever = $1; last };
    /^\s*CONFORMED .../ and do { $whatever = $1; last };
}

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If you have some idea of which matches are more likely, test them earlier.

Also, I'd advise against any of the given/when constructs, such as those shown in the Switch Statements section (immediately following the Basic BLOCKs section I linked to above), as they're experimental and not really suitable for production code.

-- Ken

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Re^2: Help with code optimization
by Anonymous Monk on Jun 28, 2013 at 13:10 UTC
    Those conditions are NOT mutually exclusive. The m modifier will cause the ^ to match any beginning of line, not just at the beginning of the string. Since $data contains the entire file, each of the expressions could match.
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Re^2: Help with code optimization
by sundialsvc4 (Abbot) on Jun 28, 2013 at 03:13 UTC

    last?   Or maybe should be next?   Do you intend to jump out of the loop, or don’t you instead really mean, continue it?

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      "last? Or maybe should be next? Do you intend to jump out of the loop, or don’t you instead really mean, continue it?"

      The loop for ($data) { ... } only executes once.

      Neither last nor next will make it execute any more or less times.

      When a match is found and the captured data is assigned to a variable, that's the last thing to be done.

      Here's what the last documentation says:

      "The last command is like the break statement in C (as used in loops); it immediately exits the loop in question."

      That's what we want to do here: immediately exit the loop.

      Here's what the next documentation says:

      "The next command is like the continue statement in C; it starts the next iteration of the loop"

      That's not what we want to do here: it's a one-pass loop; there are no more iterations.

      [You might like to follow the link I provided in my original reply. It has two more code examples where last is used to exit one-pass loops.]

      -- Ken

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