Approach 2: Instance Methods

The ProfileFetcher can be constructed and passed to TradeCalculator
When calculating trades, our tool calls the instance method

public class TradeCalculator {    
    // Set this.profileFetcher in TradeCalculator's constructor
    public Something calculateTrades(String userId) {
        ProfileData data = this.profileFetcher.fetchProfile(userId)
        // Do math !
    }
}

public class ProfileFetcher {
    public ProfileData fetchProfile(String userId) {
        // Complex SQL?
        return userProfile;
    }
}

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