🗝️ 🐀 🎸 So profitieren Sie von statischer Typisierung 🖥️ 🤽🏻 🖖🏾

Typbegrenzte Live-Daten fließen von Bundesstaat zu Bundesstaat

In diesem Artikel erfahren Sie, wie Sie das statische Typsystem beim Entwerfen Ihres Codes optimal nutzen können. Der Artikel versucht sprachunabhängig zu sein (es funktioniert nicht immer), Beispiele sind in Java und stammen aus dem Leben. Obwohl akademische Sprachen wie Idris es uns ermöglichen, nützlichere Tricks mit statischer Typisierung zu machen , und die vollständige Typinferenz die Größe der Zeremonie erheblich reduziert , schreiben wir bei der Arbeit in anderen Arten von Sprachen und möchten in der Lage sein, gute Kenntnisse anzuwenden in der Praxis, weil es unser Leben heute verbessern wird. ...

Kurze Nacherzählung der Handlung des Artikels

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    ) {
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abstract class SchemaDiff {
    final String name;

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}

final class RemovedColumn extends SchemaDiff {
    final String type;

    RemovedColumn(String name, String type) {
        super(name);
        this.type = type;
    }

    @Override
    public String toString() {
        return String.format(
            "Column %s with type %s has been removed", 
            name, 
            type
        );
    }
}

final class AddedColumn extends SchemaDiff {
    final String type;

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        super(name);
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    }

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    final String oldType;
    final String newType;

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        super(name);
        this.oldType = oldType;
        this.newType = newType;
    }

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    public String toString() {
        return String.format(
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            name, 
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        );
    }
}

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Jeder Polymorphismus ermöglicht es Ihnen, dasselbe bis zu Arten von Berechnungsdiagrammen in einem Diagramm zusammenzufassen

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void process(List<Item> items) {
    if (isLegacy) {
        List<Legacy> docs = items.stream()
            .map(x -> toLegacy(x))
            .collect(toList);
        legacyTable.store(docs);
        logEvent(docs.stream().map(x->x.getId()).collect(toList()));
    } else {
        List<Modern> docs = items.stream()
            .map(x->toModern(x, context))
            .collect(toList);
        modernTable.store(docs);
        logEvent(docs.stream().map(x->x.getId()).collect(toList()));
    }
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<T extends WithId> List<T> store(
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) {
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}

void process(List<Item> items) {
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        store(items, x -> toModern(x, context), modernTable);
    logEvent(docs);
}

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vec.push(1);

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enum FeatureType {
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}

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<TEntry extends FeatureEntry> Collection<TEntry> find(Collection<Id> ids, FeatureType type);

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enum FeatureType() {
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    ;

    private final Class<? extends FeatureEntry> entryClass;

    public FeatureType(Class<? extends FeatureEntry> entryClass) {
        this.entryClass = entryClass;
    }

    public Class<? extends FeatureEntry> getEntryClass() {
        return entryClass;
    }
}

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final class FeatureType<TEntry extends FeatureEntry> {
    public static final FeatureType<EmbeddingEntry> ELMO = 
        new FeatureType("elmo", EmbeddingEntry.class);
    public static final FeatureType<BlacklistEntry> SLANG = 
        new FeatureType("slang", BlacklistEntry.class);
    public static final FeatureType<FloatEntry> LIFETIME_7D = 
        new FeatureType("lifetime_7d", FloatEntry.class);

    private final Class<TEntry> entryClass;
    private final String name;
    private FeatureType(String name, Class<TEntry> entryClass) {
        this.name = name;
        this.entryClass = entryClass;
    }

    public String getName() {
        return name;
    }

    public Class<TEntry> getEntryClass() {
        return entryClass;
    }
}

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<TEntry extends FeatureEntry> Collection<TEntry> find(
   Collection<Id> ids, 
   FeatureType<TEntry> type
);

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    );
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<TEntry extends FeatureEntry> Collection<TEntry> find(
    Collection<Id> ids, 
    FeatureType<TEntry> type, 
    Language language
);

<TEntry extends FeatureEntry> Collection<TEntry> find(
    Collection<Id> ids, 
    FeatureType<TEntry> type, 
    Country country
);

: , runtime , .

class FeatureType<TEntry extends FeatureEntry> {
    public static final ByLanguage<EmbeddingEntry> ELMO =
        new ByLanguage<>("elmo", EmbeddingEntry.class);
    public static final ByCountry<BlacklistEntry> SLANG = 
        new ByCountry<>("slang", BlacklistEntry.class);
    public static final ByCountry<FloatEntry> LIFETIME_7D = 
        new ByCountry<>("lifetime_7d", FloatEntry.class);

    private final Class<TEntry> entryClass;
    private final String name;
    private FeatureType(String name, Class<TEntry> entryClass) {
        this.name = name;
        this.entryClass = entryClass;
    }

    public String getName() {
        return name;
    }

    static final class ByLanguage<TEntry extends FeatureEntry>
        extends FeatureType<TEntry> {...}
    static final class ByCountry<TEntry extends FeatureEntry> 
        extends FeatureType<TEntry> {...}
}

API :

<TEntry extends FeatureEntry> Collection<TEntry> find(
    Collection<Id> ids, 
    FeatureType.ByLanguage<TEntry> type, 
    Language language
);

<TEntry extends FeatureEntry> Collection<TEntry> find(
    Collection<Id> ids, 
    FeatureType.ByCountry<TEntry> type, 
    Country country
);

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//   :
private BlendedTermQuery(Term[] terms, float[] boosts, TermStates[] contexts) {
    assert terms.length == boosts.length;
    assert terms.length == contexts.length;
    this.terms = terms;
    this.boosts = boosts;
    this.contexts = contexts;
    //  terms, boosts  contexts    

    
    //     :      .
    new InPlaceMergeSorter() {
      //     terms,     .
      @Override
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        return terms[i].compareTo(terms[j]);
      }

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        Term tmpTerm = terms[i];
        terms[i] = terms[j];
        terms[j] = tmpTerm;

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        contexts[i] = contexts[j];
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        boosts[i] = boosts[j];
        boosts[j] = tmpBoost;
      }
    //   , ..  : -.
    }.sort(0, terms.length);
  }

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Foo(float[] boosts) {
    this.boosts = boosts.clone();

    new InPlaceMergeSorter() {
      @Override
      protected int compare(int i, int j) {
        return Float.compare(boosts[i], boosts[j]);
      }

      @Override
      protected void swap(int i, int j) {
        float tmpBoost = this.boosts[i];
        this.boosts[i] = this.boosts[j];
        this.boosts[j] = tmpBoost;
      }
    }.sort(0, terms.length);
  }

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Vielen Dank an diese Personen für die Überprüfung des Artikels vor der Veröffentlichung:

Dmitry Yudakov
Dmitry Petrov
Nikolay Mishuk
Anastasia Pavlovskaya
Polina Romanchenko
Svetlana Yesenkova
Yan Kornev

So profitieren Sie von statischer Typisierung

Kurze Nacherzählung der Handlung des Artikels

C

,

DSL vs composability

P.S.

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