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On 07/16/2015 05:16 PM, Alan McKinnon wrote: |
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> On 16/07/2015 22:53, walt wrote: |
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>> |
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>> If anyone can splain what introspection does I'd be grateful. |
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> It's a tricky concept if you haven't worked with Object Oriented |
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> Programming, so lt's look at the USE description: |
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> |
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> introspection - Add support for GObject based introspection |
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> |
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> Doesn't say much, right? |
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> |
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> Object Oriented languages tend to compile to byte-code, just like Java |
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> does, and so does Python. It's so the run-time interpreter can look up |
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> at run-time which function exactly needs to be run (this can't be |
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> determined statically). |
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Yes, but introspection (as a part of the language specification) is not |
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limited to object oriented languages, nor compiled to byte code |
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languages. C++'s 'virtual' keyword can (sometimes) force the compiler to |
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generate introspection code if it absolutely cannot determine which |
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function to call at compile time. C++'s templates could (maybe?) be |
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considered static introspection. |
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|
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> A really neat trick is to "look inside" objects |
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> not just to see what it has, but also how the innards work, what |
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> properties an object has, and other neat stuff. That's what introspect |
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> means - to "look inside". This magic is what makes dynamic IDEs |
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> possible, where they prompt you for all manner of stuff while typing |
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> code, and even generate boiler-plate code that it hasn't been hard-coded |
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> to deal with. |
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> |
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> All sounds very fancy and theoretical. I know what introspection does, |
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> but I can't know if I need this type of it or not. Apparently (because |
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> stuff breaks horribly when it's off), packages that use GObject seem to |
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> rely on this feature. |
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It is very nice and very fancy, but the implementation is not incredibly |
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complicated in most languages (just pointers to tables of functions if |
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memory serves). If anyone is interested in playing around with this |
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stuff, Ruby has a pretty advanced object model, and classes can have |
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different function implementations depending on what module you're in. |
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Alec |
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