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All the Perl that's Practical to Extract and Report

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  • You missed three key features:
    • No Closures (Tcl messes this up; I think Python does too...)
    • No eval (C, C++, Java; makes it much harder to do macros and code generation...)
    • No variable interpolation (printf is just soooo lame)

    Now, with interpolation and eval, you can fake closures, but it's a royal PITA. Here's the classic make_adder example in Perl:

    sub make_adder ($) {
         my $i = shift;
         return sub {
             return shift() + $i;
       

    • I think much of that can be summed up as "allow dynamic code generation" and "have code with some data attached". And to be able to do these things easily. Java, for example, limps along using pre-processors (IDEs, AspectJ, ...) for the former and anonymous classes for the latter.
      • Respectfully, no it's not. You really do need closures. Hey, it's 21st century -- get with the program! ;-)

        Reducing this down to "allow dynamic code generation" and "attach data to code" is a false economy in specification. Once you have true closures (which imply lexical scoping), a whole new way to code is opened up for you. Instead of writing ridiculously long classes to, say, find files, you can have small simple classes that are responsible for the algorithmic structure of finding files and nothi

        • I think we're having a violent agreement.

          By changing the wording from "have closures" to "easily attach data to code" (with the implied "at runtime") I was attempting to restate the problem as a problem rather than as a solution. Closures are a solution to the problem and you've layed out the problem quite well. I would rather not assume that closures are the only way to do it. Or eval. Or pluggable functions (*foo = \&bar). Maybe there is a way to do it efficiently and concisely with anonymous cl
          • by ziggy (25) on 2005.04.10 18:58 (#39565) Journal
            Hm.

            As you stated the problem above, there are some design decisions that are fundementally wrong in language design today. Like no namespaces, no way to include files, etc.

            "No Closures" is as big a design flaw as "no anonymous functions", "no eval" and "no interpolation". You can find all sorts of ways around that problem, but fundementally, there's no good reason to not have closures. Rephrasing that, there's no defensible reason for asking your users to jump through hoops to achieve the same result (like Python's hackish way of using anonymous objects with a __getattr__ method).

            I think you're focusing on the impact rather than on the language feature. Yet you started with a list of language features.

            From what I've seen elsewhere, wiggling around the problem of closures by making the moral equivalent of a closure available is just as much of a problem. Even Smalltalk has closures, even though they call them "anonymous blocks". Whatever you call them, they're pretty much a requirement today.