From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: fac41,9a0ff0bffdf63657 X-Google-Attributes: gidfac41,public X-Google-Thread: f43e6,9a0ff0bffdf63657 X-Google-Attributes: gidf43e6,public X-Google-Thread: 1108a1,9a0ff0bffdf63657 X-Google-Attributes: gid1108a1,public X-Google-Thread: 103376,4b06f8f15f01a568 X-Google-Attributes: gid103376,public From: "Robert Martin" Subject: Re: Software landmines (loops) Date: 1998/09/06 Message-ID: <6su70s$db8$1@hirame.wwa.com>#1/1 X-Deja-AN: 388411278 References: <902934874.2099.0.nnrp-10.c246a717@news.demon.co.uk> <6r1glm$bvh$1@nnrp1.dejanews.com> <6r9f8h$jtm$1@nnrp1.dejanews.com> <6renh8$ga7$1@nnrp1.dejanews.com> <6rf59b$2ud$1@nnrp1.dejanews.com> <6rfra4$rul$1@nnrp1.dejanews.com> <35DBDD24.D003404D@calfp.co.uk> <6sbuod$fra$1@hirame.wwa.com> <35f51e53.48044143@ <904556531.666222@miso.it.uq.edu.au> <6sgror$je8$3@news.indigo.ie> <6sh3qn$9p2$1@hirame.wwa.com> <6shbca$66c$1@news.indigo.ie> <6shhq7$lut$1@hirame.wwa.com> <6sjbso$1lk$2@news.indigo.ie> <6sjijg$36r$1@hirame.wwa.com> <6skhcm$1dr$2@news.indigo.ie> <6skqf3$9g0$1@hirame.wwa.com> <6smmhv$1kp$1@nnrp1.dejanews.com> <6smsi3$n8i$1@hirame.wwa.com> <35F2496D.7C4BDC42@earthlink.net> X-MimeOLE: Produced By Microsoft MimeOLE V4.72.2106.4 Organization: WorldWide Access - Midwestern Internet Services - www.wwa.com Newsgroups: comp.lang.eiffel,comp.object,comp.software-eng,comp.lang.ada Date: 1998-09-06T00:00:00+00:00 List-Id: Charles Hixson wrote in message <35F2496D.7C4BDC42@earthlink.net>... >Robert Martin wrote: >... >> if (condition.1) return; >> else if (condition.2) return; >> else do something useful; >> return; >> }; >> >> Which, in reality, is: >> >> void f() >> { >> if (condition.1) return; >> else{ >> if (condition.2) return; >> else { >> do something useful; >> } >> } >> }; >> >> So, early returns do not actually reduce nesting; they just appear to. The >... >> >> Robert C. Martin | Design Consulting | Training courses offered: >> Object Mentor | rmartin@oma.com | Object Oriented Design >> 14619 N Somerset Cr | Tel: (800) 338-6716 | C++ >> Green Oaks IL 60048 | Fax: (847) 918-1023 | http://www.oma.com >> >> "One of the great commandments of science is: >> 'Mistrust arguments from authority.'" -- Carl Sagan >If you are going to use else-if's, then the early return doesn't >accomplish anything, and the routine could be rephrased as: > void f() > { > if (!condition.1 & !condition.2) > { do something useful; > } > }; > >Just a transform, I know. But, actually, that's my point. PRECISELY! Early returns form a boolean equation which is an OR of terms: if this then return. or if that then return. or if the_other then return or do something useful. But, as you noted, we can apply Demorgan's theorem and turn this into an AND of factors if (!this AND !that AND !the_other) then do something useful Just a transformation, And one that turns a multiple exit function into an se/se function. we might then decide that long boolean equations are better split apart: if (!this) if (!that) if (!the_other) then do something useful. Which is an idiom that we can learn to read as a set of ANDS. Robert C. Martin | Design Consulting | Training courses offered: Object Mentor | rmartin@oma.com | Object Oriented Design 14619 N Somerset Cr | Tel: (800) 338-6716 | C++ Green Oaks IL 60048 | Fax: (847) 918-1023 | http://www.oma.com "One of the great commandments of science is: 'Mistrust arguments from authority.'" -- Carl Sagan