in reply to Re^4: Perl vs Python revisited
in thread Perl vs Python revisited

My personal criteria is that a number used once, is just a number. Used more than once -- to represent the same value -- it should be a symbolic constant or enum.
From magic number (wikipedia), some possible exceptions: If 0, 1, 2, 100 in the examples above were used more than once in your program, would you create a symbolic name for them?

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Re^6: Perl vs Python revisited
by BrowserUk (Patriarch) on Jan 07, 2017 at 21:27 UTC
    If 0, 1, 2, 100 in the examples above were used more than once in your program, would you create a symbolic name for them?

    Not for the uses in your examples.

    I do use enums for 0 and 1 where they are indexes in multi-dimensional arrays with the 0th element being an X coordinate and 1 the Y coordinate; and similar examples.

    This is the results of a grep for "enum" in *.pl files in my junk directory:

    1031775.pl:use enum qw[ NAME FREQ LEFT RIGHT ];
1161363.pl:use enum qw[ IN DBI ];
1161647.pl:use enum qw[ IN DBI_ENUM ];
1177385.pl:use enum qw[ IN DBI_ENUM ];
904729-2.pl:use enum qw[ CODE GRAPH START PATH SEEN ];
904729-3.pl:    use enum qw[ CODE GRAPH START PATH SEEN ];
CIDR.pl:use enum qw[ CIDR NETWORK SIZE RANGE ];
CIDR.pl:use enum qw[ FIRST LAST ];
dumpTree.pl:use enum qw[ LEFT RIGHT ];
dumpTree.pl:use enum qw[ WIDTH DEPTH NAME ];
FPstuff.pl:use enum qw[ X Y ];
GraphBench.pl:    use enum qw[ CODE GRAPH START END PATH ];
GraphBench.pl:    use enum qw[ CODE GRAPH START END PATH ];
hFP.pl:    use enum 'KEY', 'VAL';
lazyTree.pl:use enum qw[ LEFT RIGHT ];
philo3.pl:use enum qw[LEFT RIGHT ALL];
plotTSP.pl:use enum qw[ X Y ];
plotTSP2.pl:use enum qw[ X Y ];
plotTSP3.pl:use enum qw[ X Y ];
SameFringe.pl:use enum qw[ LEFT RIGHT ];

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Re^6: Perl vs Python revisited
by jdporter (Paladin) on Jan 09, 2017 at 21:28 UTC
    0, 1, 2, 100 ...

    And that's the difference between "magic" number and "hard-coded" number.

    Obviously, not all numeric literals are magic.

    I reckon we are the only monastery ever to have a dungeon stuffed with 16,000 zombies.
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Re^6: Perl vs Python revisited
by LanX (Saint) on Jan 07, 2017 at 21:50 UTC
    For completeness

    I've already seen code binding 0 and 1 to false and true .

    edit

    of course only in boolean context.

    update

    But I wouldn't be surprised if some people called Perl's use of 0 and 1 in these cases magic numbers.

    Cheers Rolf
    (addicted to the Perl Programming Language and ☆☆☆☆ :)
    Je suis Charlie!

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