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GitLab utilities

We developed a number of utilities to ease development.

MergeHash

  • Deep merges an array of hashes:

    Gitlab::Utils::MergeHash.merge([{hello:["world"]},{hello:"Everyone"},{hello:{greetings:['Bonjour','Hello','Hallo','Dzien dobry']}},“再见”,"Hallo"])

    Gives:

    [{hello:["world","Everyone",{greetings:['Bonjour','Hello','Hallo','Dzien dobry']}]},“再见”]

  • Extracts all keys and values from a hash into an array:

    Gitlab::Utils::MergeHash.crush({hello:"world",this:{crushes:["an entire","hash"]}})

    Gives:

    [:hello,"world",:this,:crushes,"an entire","hash"]

Override

  • This utility could help us check if a particular method would override another method or not. It has the same idea of Java's@Overrideannotation or Scala'soverridekeyword. However we only do this check whenENV['STATIC_VERIFICATION']is set to avoid production runtime overhead. This is useful to check:

    • If we have typos in overriding methods.
    • If we renamed the overridden methods, making original overriding methods overrides nothing.

    Here's a simple example:

    classBasedefexecuteendendclass派生的<Baseextend::Gitlab::Utils::Overrideoverride:execute# /ride check happens heredefexecuteendend

    This also works on modules:

    moduleExtensionextend::Gitlab::Utils::Overrideoverride:execute# Modules do not check this immediatelydefexecuteendendclass派生的<BaseprependExtension# /ride check happens here, not in the moduleend

StrongMemoize

  • Memoize the value even if it is零orfalse.

    We often do@value ||= compute, however this doesn't work well ifcomputemight eventually give零and we don't want to compute again. Instead we could usedefined?to check if the value is set or not. However it's tedious to write such pattern, andStrongMemoizewould help us use such pattern.

    Instead of writing patterns like this:

    classFinddefresultreturn@resultifdefined?(@result)@result=searchendend

    We could write it like:

    classFindincludeGitlab::Utils::StrongMemoizedefresultstrong_memoize(:result)dosearchendendend

  • 清晰的记忆

    classFindincludeGitlab::Utils::StrongMemoizeendFind.new.clear_memoization(:result)
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