Hello,<div> </div><div>Disclaimer: I am new to Racket, so please forgive the ignorance. </div><div> </div><div>Questions:</div><div>1) As a functional language, when Racket implemented classes did it do so with a different perspective or design philosophy than procedural languages that made a similar transition? In other words, what is the correct, Rackety way to think about and to use classes?</div> <div> </div><div>2) Reading through the documentation it seems that there are three different ways to update fields:</div><div> </div><div>Way 1:</div><div><table cellspacing="0" class="RktBlk" style="white-space:inherit;text-align:left;font-family:serif;background-color:rgb(255,255,255)"> <tbody><tr style="white-space:inherit"><td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit">(<a href="http://docs.racket-lang.org/reference/createclass.html#(form._((lib._racket/private/class-internal..rkt)._class))" class="RktStxLink" style="text-decoration:none;color:black">class</a> <a href="http://docs.racket-lang.org/reference/createclass.html#(def._((lib._racket/private/class-internal..rkt)._object~25))" class="RktValLink" style="text-decoration:none;color:blue">object%</a></td> </tr><tr style="white-space:inherit"><td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> (<a href="http://docs.racket-lang.org/reference/createclass.html#(form._((lib._racket/private/class-internal..rkt)._init))" class="RktStxLink" style="text-decoration:none;color:black">init</a> size) ; initialization argument</td> </tr><tr style="white-space:inherit"><td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> </td></tr><tr style="white-space:inherit"> <td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> (<a href="http://docs.racket-lang.org/reference/define.html#(form._((lib._racket/private/base..rkt)._define))" class="RktStxLink" style="text-decoration:none;color:black">define</a> current-size size) ; field</td> </tr><tr style="white-space:inherit"><td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> </td></tr><tr style="white-space:inherit"> <td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> (<a href="http://docs.racket-lang.org/reference/objcreation.html#(form._((lib._racket/private/class-internal..rkt)._super-new))" class="RktStxLink" style="text-decoration:none;color:black">super-new</a>) ; superclass initialization</td> </tr><tr style="white-space:inherit"><td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> </td></tr><tr style="white-space:inherit"> <td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> (<a href="http://docs.racket-lang.org/reference/createclass.html#(form._((lib._racket/private/class-internal..rkt)._define/public))" class="RktStxLink" style="text-decoration:none;color:black">define/public</a> (get-size)</td> </tr><tr style="white-space:inherit"><td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> current-size)</td> </tr><tr style="white-space:inherit"><td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> </td></tr><tr style="white-space:inherit"> <td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> (<a href="http://docs.racket-lang.org/reference/createclass.html#(form._((lib._racket/private/class-internal..rkt)._define/public))" class="RktStxLink" style="text-decoration:none;color:black">define/public</a> (grow amt)</td> </tr><tr style="white-space:inherit"><td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> (<a href="http://docs.racket-lang.org/reference/set_.html#(form._((quote._~23~25kernel)._set!))" class="RktStxLink" style="text-decoration:none;color:black">set!</a> current-size (<a href="http://docs.racket-lang.org/reference/generic-numbers.html#(def._((quote._~23~25kernel)._+))" class="RktValLink" style="text-decoration:none;color:blue">+</a> amt current-size)))</td> </tr><tr style="white-space:inherit"><td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> </td></tr><tr style="white-space:inherit"> <td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> (<a href="http://docs.racket-lang.org/reference/createclass.html#(form._((lib._racket/private/class-internal..rkt)._define/public))" class="RktStxLink" style="text-decoration:none;color:black">define/public</a> (eat other-fish)</td> </tr><tr style="white-space:inherit"><td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> (grow (<a href="http://docs.racket-lang.org/reference/ivaraccess.html#(form._((lib._racket/private/class-internal..rkt)._send))" class="RktStxLink" style="text-decoration:none;color:black">send</a> other-fish get-size)))) </td></tr></tbody></table></div><div> </div><div>Way 2:</div><div>(<a href="http://docs.racket-lang.org/reference/define.html#(form._((lib._racket/private/base..rkt)._define))" class="RktStxLink" style="text-decoration:none;color:black">define</a> account% </div> <div>(<a href="http://docs.racket-lang.org/reference/createclass.html#(form._((lib._racket/private/class-internal..rkt)._class))" class="RktStxLink" style="text-decoration:none;color:black">class</a> <a href="http://docs.racket-lang.org/reference/createclass.html#(def._((lib._racket/private/class-internal..rkt)._object~25))" class="RktValLink" style="text-decoration:none;color:blue">object%</a> </div> <div>(<a href="http://docs.racket-lang.org/reference/objcreation.html#(form._((lib._racket/private/class-internal..rkt)._super-new))" class="RktStxLink" style="text-decoration:none;color:black">super-new</a>) </div> <div>(<a href="http://docs.racket-lang.org/reference/createclass.html#(form._((lib._racket/private/class-internal..rkt)._init-field))" class="RktStxLink" style="text-decoration:none;color:black">init-field</a> balance) </div> <div>(<a href="http://docs.racket-lang.org/reference/createclass.html#(form._((lib._racket/private/class-internal..rkt)._define/public))" class="RktStxLink" style="text-decoration:none;color:black">define/public</a> (add n) </div> <div>(<a href="http://docs.racket-lang.org/reference/objcreation.html#(form._((lib._racket/private/class-internal..rkt)._new))" class="RktStxLink" style="text-decoration:none;color:black">new</a> <a href="http://docs.racket-lang.org/reference/createclass.html#(form._((lib._racket/private/class-internal..rkt)._this~25))" class="RktStxLink" style="text-decoration:none;color:black">this%</a> [balance (<a href="http://docs.racket-lang.org/reference/generic-numbers.html#(def._((quote._~23~25kernel)._+))" class="RktValLink" style="text-decoration:none;color:blue">+</a> n balance)]))))</div> <div> </div><div> </div><div>Way 3:</div><div><table cellspacing="0" class="RktBlk" style="white-space:inherit;text-align:left;font-family:serif;background-color:rgb(255,255,255)"><tbody><tr style="white-space:inherit"> <td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit">(<a href="http://docs.racket-lang.org/reference/define.html#(form._((lib._racket/private/base..rkt)._define))" class="RktStxLink" style="text-decoration:none;color:black">define</a> savings%</td> </tr><tr style="white-space:inherit"><td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> (<a href="http://docs.racket-lang.org/reference/createclass.html#(form._((lib._racket/private/class-internal..rkt)._class))" class="RktStxLink" style="text-decoration:none;color:black">class</a> account%</td> </tr><tr style="white-space:inherit"><td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> (<a href="http://docs.racket-lang.org/reference/objcreation.html#(form._((lib._racket/private/class-internal..rkt)._super-new))" class="RktStxLink" style="text-decoration:none;color:black">super-new</a>)</td> </tr><tr style="white-space:inherit"><td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> (<a href="http://docs.racket-lang.org/reference/createclass.html#(form._((lib._racket/private/class-internal..rkt)._inherit-field))" class="RktStxLink" style="text-decoration:none;color:black">inherit-field</a> balance)</td> </tr><tr style="white-space:inherit"><td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> (<a href="http://docs.racket-lang.org/reference/define.html#(form._((lib._racket/private/base..rkt)._define))" class="RktStxLink" style="text-decoration:none;color:black">define</a> interest 0.04)</td> </tr><tr style="white-space:inherit"><td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> (<a href="http://docs.racket-lang.org/reference/createclass.html#(form._((lib._racket/private/class-internal..rkt)._define/public))" class="RktStxLink" style="text-decoration:none;color:black">define/public</a> (add-interest)</td> </tr><tr style="white-space:inherit"><td style="padding-left:0px;padding-right:0px;vertical-align:baseline;white-space:inherit"> (<a href="http://docs.racket-lang.org/reference/ivaraccess.html#(form._((lib._racket/private/class-internal..rkt)._send))" class="RktStxLink" style="text-decoration:none;color:black">send</a> <a href="http://docs.racket-lang.org/reference/createclass.html#(form._((lib._racket/private/class-internal..rkt)._this))" class="RktStxLink" style="text-decoration:none;color:black">this</a> add (<a href="http://docs.racket-lang.org/reference/generic-numbers.html#(def._((quote._~23~25kernel)._*))" class="RktValLink" style="text-decoration:none;color:blue">*</a> interest balance)))))</td> </tr></tbody></table> </div><div>How do these approaches differ? And when should I use one over the other?</div><div> </div><div>Many Thanks,</div><div>Hillary Ryan</div><div> </div>