has

Australia's #1 for Law
Join 150,000 Australians every month. Ask a question, respond to a question and better understand the law today!
FREE - Join Now
In database design, object-oriented programming and design (see object oriented program architecture), has-a (has_a or has a) is a composition relationship where one object (often called the constituted object, or part/constituent/member object) "belongs to" (is part or member of) another object (called the composite type), and behaves according to the rules of ownership. In simple words, has-a relationship in an object is called a member field of an object. Multiple has-a relationships will combine to form a possessive hierarchy.
This is to be contrasted with an is-a (is_a or is a) relationship which constitutes a taxonomic hierarchy (subtyping).
The decision whether the most logical relationship for an object and its subordinate is not always clearly has-a or is-a. Confusion over such decisions have necessitated the creation of these metalinguistic terms. A good example of the has-a relationship is containers in the C++ STL.
To summarize the relations, we have

hypernym-hyponym (supertype-subtype) relations between types (classes) defining a taxonomic hierarchy, where
for an inheritance relation: a hyponym (subtype, subclass) has a type-of (is-a) relationship with its hypernym (supertype, superclass);
holonym-meronym (whole/entity/container-part/constituent/member) relations between types (classes) defining a possessive hierarchy, where
for an aggregation (i.e. without ownership) relation:
a holonym (whole) has a has-a relationship with its meronym (part),
for a composition (i.e. with ownership) relation:
a meronym (constituent) has a part-of relationship with its holonym (entity),
for a containment relation:
a meronym (member) has a member-of relationship with its holonym (container);
concept-object (type-token) relations between types (classes) and objects (instances), where
a token (object) has an instance-of relationship with its type (class).

View More On Wikipedia.org
  1. L

    SA Tricky Mother has had Daughter Assessed for Autism

    Thank you for answering my questions. This is a tricky situation, the mother of the child (daughter) has paid for a autism assessment in which she has lied and stated the father has no contact or involvement with the child. The mother has signed a legal contract stating this to the...
  2. M

    NSW No Stopping sign not present when we parked at 2P streetside sign but has appeared in revenuensw photos as a very slanted sign on top of the 2P sign

    My wife drove our family to eat at about 5:35pm near Star City Casino on 16 May. Both of us looked at the 2P sign that was outside the restaurant before we decided to park there as we could only see 2P till 6am-6pm. So we only paid to 6pm & thought we can continue to park there unrestricted...
  3. T

    NSW right of carriageway

    I share my drive way with my neighbour for about 10 years but has been hard on us since he does not follow the terms of the right of carriageway. He can build a driveway to get in his garage but he prefer not to and keep his car parked on the driveway because I have another driveway. I can't ask...
  4. J

    VIC Abusive husband has IVO on me and wants custody of our children.

    My husband has been coercively controlling me throughout our marriage. During COVID lockdown it got really bad and I needed to do something about it so I suggested we should get counselling together which he refused. At this time, I was aware he was involved with an ex girlfriend. I caught him...
  5. S

    NSW Damages awarded in court years ago Company has never paid

    Hi, have a situation where a court awarded damages for unfair dismissal/bullying to an ex employee. The damages have never been paid to the ex employee. They did have a few breakdowns and has been struggling with mental health issues post the closure of the case. What avenues do we have to...
  6. F

    New e-bike that has given endless problems

    I bought an e-bike a bit over a month ago. In that time - it has given endless problems. The pedal assist shuts off constantly. If there is any moisture on the ground the engine dies. Surely, by ACL standards a bicycle should handle the mildest of situations? I politely asked for some help and...
  7. D

    VIC changing conditions on an ivo

    my partner has an ivo against me but did not want me to stop seeing her or contacting her, she is not well as she is battling a terminal illness and can not go to court to change this is there another way at all because so far i have been charged wuth 5 breaches and spent 3 nights in jail just...
  8. R

    NSW builder underestimated cost, inflates invoices, gives false invoice, removes tools from site

    Any advise on the following please.if I have left out any vital information, please advise... I engaged the builder to convert my investment property, a terrace house into a 3 room boarding house with internal renovation work only. The renovation was to be developed in two stages, with a budget...
  9. G

    SA Partner has no access to son. Mother ignoring all contact and mediation.

    Okay so. My partner found out he has a son from a one night stand before we were together. He had no idea until a friend of the mother's sent a Facebook msg to him out of the blue stating that he has a son. That he is in danger and being neglected. Partner contacted the mother to organise a DNA...
  10. A

    VIC Magistrate court has revoked an IVO without me presenting further and better particulars

    Hello members I have an interim IVO in place, a mentions hearing was conducted recently with a contested hearing due in March 2021. The court advised to provide further and better particulars before this date (from memory 2 weeks before, don't have the paperwork in front of me now). The ex has...