FAQ 1.13 Is it a Perl program or a Perl script? #4

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1.13: Is it a Perl program or a Perl script?

    Larry doesn't really care. He says (half in jest) that "a script is what
    you give the actors. A program is what you give the audience."

    Originally, a script was a canned sequence of normally interactive
    commands--that is, a chat script. Something like a UUCP or PPP chat
    script or an expect script fits the bill nicely, as do configuration
    scripts run by a program at its start up, such .cshrc or .ircrc, for
    example. Chat scripts were just drivers for existing programs, not
    stand-alone programs in their own right.

    A computer scientist will correctly explain that all programs are
    interpreted and that the only question is at what level. But if you ask
    this question of someone who isn't a computer scientist, they might tell
    you that a *program* has been compiled to physical machine code once and
    can then be run multiple times, whereas a *script* must be translated by
    a program each time it's used.

    Perl programs are (usually) neither strictly compiled nor strictly
    interpreted. They can be compiled to a byte-code form (something of a
    Perl virtual machine) or to completely different languages, like C or
    assembly language. You can't tell just by looking at it whether the
    source is destined for a pure interpreter, a parse-tree interpreter, a
    byte-code interpreter, or a native-code compiler, so it's hard to give a
    definitive answer here.

    Now that "script" and "scripting" are terms that have been seized by
    unscrupulous or unknowing marketeers for their own nefarious purposes,
    they have begun to take on strange and often pejorative meanings, like
    "non serious" or "not real programming". Consequently, some Perl
    programmers prefer to avoid them altogether.


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comdog (395)
7/14/2005 4:03:01 AM
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