[LUCY-146] Reduce iterator variable scopes

• Type: Sub-task
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 0.3.1
• Assignee: Logan J. Bell
• Reporter: Marvin Humphrey
• Created: 16/May/11 00:56
• Updated: 19/Mar/12 19:28
• Resolved: 19/Mar/12 19:28

Description

C99 allows you to declare iterator variables within "for" loops, but C89 does
not:

    // C99
    for (int i = 0, max = 10; i < max; i++) {
        // ...
    }

    /* C89 */
    int i, max;
    for (i = 0, max = 10; i < max; i++) {
        /* ... */
    }

The C99 idiom is superior because it limits the scope of the iterator
variable.

We have a number of C89-style iterator variables which should be switched
over. In some cases, the iterator variable is declared at the top of a scope
and then reused within several loops. That's the sort of pattern we'd like to
avoid.

The following crude grep command detects some candidates which ought to be
reviewed:

grep -r "for ([a-z] =" lucyalt | grep -v -e "svn\|charmonizer\|modules\|\.pm"

Care must be taken when performing this refactoring, because some code may
in fact be relying on iterator variables holding values across multiple
loops – such as in PriorityQueue.c. It will be good when this refactoring
pass is finished because such code will stand out more.