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at:tutorial:reflection [2007/04/27 12:58] stijnm Added |
at:tutorial:reflection [2010/11/16 16:32] tvcutsem |
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- | ====== Reflective Programming ====== | ||
- | Reflection is an integral part of the AmbientTalk programming language. Through the use of reflection, the core language can be extended with both programming support as well as new language constructs. Both examples require a different kind of reflective access. The introduction of programming support (e.g. to visualise AmbientTalk objects) relies on **introspection**, | ||
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- | The reflective model of AmbientTalk is based on **mirrors**, | ||
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- | ===== Mirrors ===== | ||
- | As we have already mentioned in the introduction, | ||
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- | < | ||
- | def baseObject := object: { | ||
- | def field := nil; | ||
- | def canonicalMethod() { nil } | ||
- | def keyworded: arg1 method: arg2 { nil } | ||
- | }; | ||
- | def mirror := reflect: baseObject; | ||
- | def slots := mirror.listSlots(); | ||
- | slots.each: { | slot | system.println() }; | ||
- | </ | ||
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- | The code excerpt presented above uses the mirror to // | ||
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- | In addition to allowing a program to reason about the structure of its objects, mirrors can also be used to write operations such as message sending in a first-class manner. The following example uses this power to invoke a zero-argument method, whose name is specified at runtime by requesting input from the user. | ||
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- | < | ||
- | def invokeUserMethod(object) { | ||
- | def userInput := read: (system.readln()); | ||
- | // This example assumes that the user typed a single symbol | ||
- | (reflect: object).invoke(object, | ||
- | }; | ||
- | </ | ||
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- | This part of the tutorial has provided a basic feeling of how AmbientTalk' |