# Naming convention for structs **URL:** \ **Category:** Questions & Answers\ **Created:** [May 30, 2024, 1:05pm UTC](https://racket.discourse.group/t/naming-convention-for-structs/2939 "2024-05-30T13:05:39Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![rvdalen](https://avatars.discourse-cdn.com/v4/letter/r/b4bc9f/32.png) [@rvdalen](https://racket.discourse.group/u/rvdalen)\ **Post date:** [May 30, 2024, 1:05pm UTC](https://racket.discourse.group/t/naming-convention-for-structs/2939/1 "2024-05-30T13:05:39Z")
Hi everyone, I am wondering if anyone else has run into this issue and if there is some commonly-used work-around? The issue is the name of my struct and the name of a binding for an instance of the struct usually ends up having the same name which causes issues. For example: ```scheme (struct person (name age)) (define (person-update-age person new-age) (struct-copy person person [age new-age])) ``` The problem is I would like to name the parameter to the `person-update-age` also person. This then shadows the `person` struct-id and causes the code to raise an error. I was thinking of adding '$' to my struct names to avoid this conflict. For example: ```scheme (struct $person (name age)) (define (person-update-age person new-age) (struct-copy $person person [age new-age])) ``` This seems to work ok, but I would like to check if there is already a community-established convention for this situation? Regards ---
**Author:** ![sorawee](https://avatars.discourse-cdn.com/v4/letter/s/ea5d25/32.png) [@sorawee](https://racket.discourse.group/u/sorawee)\ **Post date:** [May 30, 2024, 1:54pm UTC](https://racket.discourse.group/t/naming-convention-for-structs/2939/2 "2024-05-30T13:54:02Z")
This is a FAQ. See a recent discussion at [https://racket.discourse.group/t/choosing-good-names/2900](https://racket.discourse.group/t/choosing-good-names/2900) . TL;DR: some people use `a-person` / `the-person` for an instance of `person`. Some people abbreviate instance names. But there’s not really a “community-established convention”. ---
**Author:** ![hendrikboom3](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/hendrikboom3/32/2748_2.png) [@hendrikboom3](https://racket.discourse.group/u/hendrikboom3)\ **Post date:** [May 30, 2024, 4:46pm UTC](https://racket.discourse.group/t/naming-convention-for-structs/2939/3 "2024-05-30T16:46:01Z")
I've seen the a- / the- notation used in a somewhat readable formal semantics system. It used 'a-' when introducing a parameter (binding it), and 'the' when referring to it. eg. To increment a number add one to the number. Unfortunately, 'a-person' and 'the-person' are recognised in Racket as having nothing whatsoever to do with each other. -- hendrik ---
**Author:** ![dstorrs](https://avatars.discourse-cdn.com/v4/letter/d/898d66/32.png) [@dstorrs](https://racket.discourse.group/u/dstorrs)\ **Post date:** [May 30, 2024, 7:36pm UTC](https://racket.discourse.group/t/naming-convention-for-structs/2939/4 "2024-05-30T19:36:04Z")
One thought: if you're writing these update/set functions yourself, you're doing more work than you need to. Check [struct-plus-plus](https://docs.racket-lang.org/struct-plus-plus/index.html). ```scheme #lang racket (require struct-plus-plus) (struct++ person (name age) #:transparent) (define bob (person 'bob 17)) bob ; Displays: (person 'bob 17) (set-person-age bob 18) ; functional update, not mutational ; Displays: (person 'bob 18) (set-person-age bob (add1 (person.age bob))) ; Displays: (person 'bob 18) (update-person-age bob (λ (current-val) (+ 10 current-val))) ; Displays: (person 'bob 27) ; Also, keyword constructor and all fields have setters/updaters (person++ #:name 'bob #:age 37) ; Displays: (person 'bob 37) (set-person-name bob 'tom) ; Displays: (person 'tom 17) ``` ---
**Author:** ![soegaard](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/soegaard/32/19_2.png) [@soegaard](https://racket.discourse.group/u/soegaard)\ **Post date:** [May 30, 2024, 10:00pm UTC](https://racket.discourse.group/t/naming-convention-for-structs/2939/5 "2024-05-30T22:00:21Z")
If we want, we can make `the-number` refer to `a-number` by defining a custom `top`. ```scheme #lang racket/base (require (for-syntax racket/base racket/syntax syntax/parse)) (provide (rename-out [my-top #%top])) (define-syntax (my-top stx) (syntax-parse stx [(_my-top . id:id) (define str (symbol->string (syntax-e #'id))) (define n (string-length str)) (if (and (>= n 4) (string=? (substring str 0 4) "the-")) (with-syntax ([a (format-id #'id "a-~a" (substring str 4 n))]) (syntax/loc #'id a)) (syntax/loc stx (#%top . id)))])) ``` Now the following program works: ```scheme (require "the-top.rkt") (define (subscript a-string a-number) (~a the-string "_" the-number)) (subscript "foo" 42) ``` ---
**Author:** ![soegaard](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/soegaard/32/19_2.png) [@soegaard](https://racket.discourse.group/u/soegaard)\ **Post date:** [May 30, 2024, 10:02pm UTC](https://racket.discourse.group/t/naming-convention-for-structs/2939/6 "2024-05-30T22:02:16Z")
Use `p` as short for the person. Note that field accessors are prefixed with the struct name (here `person`). Thus in an expression like `(person-age p)` no one doubts that `p` is a person. ---
**Author:** ![rvdalen](https://avatars.discourse-cdn.com/v4/letter/r/b4bc9f/32.png) [@rvdalen](https://racket.discourse.group/u/rvdalen)\ **Post date:** [May 31, 2024, 12:13pm UTC](https://racket.discourse.group/t/naming-convention-for-structs/2939/7 "2024-05-31T12:13:16Z")
Thanks everyone, The `person-update-age` function is just for the example. I do not write those types of functions 🙂 I like the `a-person` convention for the binding. I will try a couple of things and see what works for me. Regards ---
**Author:** ![hendrikboom3](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/hendrikboom3/32/2748_2.png) [@hendrikboom3](https://racket.discourse.group/u/hendrikboom3)\ **Post date:** [May 31, 2024, 2:11pm UTC](https://racket.discourse.group/t/naming-convention-for-structs/2939/8 "2024-05-31T14:11:02Z")
Interesting. I had no idea that was possible. It's worth further study. Do I presume correctly that it does not restrict the 'the-' form to binding occurrences and the 'a-' form to bound occurrances? -- hendrik ---
**Author:** ![soegaard](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/soegaard/32/19_2.png) [@soegaard](https://racket.discourse.group/u/soegaard)\ **Post date:** [May 31, 2024, 2:56pm UTC](https://racket.discourse.group/t/naming-convention-for-structs/2939/9 "2024-05-31T14:56:16Z")
> Do I presume correctly that it does not restrict the 'the-' form to binding > occurrences and the 'a-' form to bound occurrances? Consider the example: ```scheme (define (foo a-number) (+ the-number 1)) ``` Here `the-number` is unbound, so the expander expands into `(#%top . the-number)`. Since we imported `#%top` from a module that exported `my-top` as `#%top`, the expander continues looking at `(my-top . the-number)`. The transformer of `my-top` looks at the identifier. If it begins with `the-` it rewrites it to an identifier that begins with `a-` instead. Here it becomes `a-number` (and has the same context as the original identifier). If the identifier doesn't begin with `the-` it just leaves it as-is. In short, all unbound references caused by identifiers of the form `the-x` are rewritten into references of the form `a-x`. ---
**Author:** ![hendrikboom3](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/hendrikboom3/32/2748_2.png) [@hendrikboom3](https://racket.discourse.group/u/hendrikboom3)\ **Post date:** [May 31, 2024, 3:19pm UTC](https://racket.discourse.group/t/naming-convention-for-structs/2939/10 "2024-05-31T15:19:55Z")
Of course I meant to have written this the other way around: Do I presume correctly that it does not restrict the 'a-' form to binding occurrences and the 'the-' form to bound occurrances? -- hendrik ---
**Author:** ![rvdalen](https://avatars.discourse-cdn.com/v4/letter/r/b4bc9f/32.png) [@rvdalen](https://racket.discourse.group/u/rvdalen)\ **Post date:** [May 31, 2024, 3:49pm UTC](https://racket.discourse.group/t/naming-convention-for-structs/2939/11 "2024-05-31T15:49:03Z")
Actually after playing around with different options, adding a '^' suffix for structs feels better and I will switch to that as a convention. 😀 ---
**Author:** ![soegaard](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/soegaard/32/19_2.png) [@soegaard](https://racket.discourse.group/u/soegaard)\ **Post date:** [May 31, 2024, 5:08pm UTC](https://racket.discourse.group/t/naming-convention-for-structs/2939/12 "2024-05-31T17:08:38Z")
An suffix ^ is already used for units. [https://docs.racket-lang.org/guide/Signatures\_and\_Units.html](https://docs.racket-lang.org/guide/Signatures_and_Units.html) ---
**Author:** ![soegaard](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/soegaard/32/19_2.png) [@soegaard](https://racket.discourse.group/u/soegaard)\ **Post date:** [May 31, 2024, 5:12pm UTC](https://racket.discourse.group/t/naming-convention-for-structs/2939/13 "2024-05-31T17:12:52Z")
> Do I presume correctly that it does not restrict the 'a-' form to binding > occurrences and the 'the-' form to bound occurrances? Well, the macro does nothing more than: > In short, all unbound references caused by identifiers of the form `the-x` are rewritten into references of the form `a-x` . So an `a-` identifier behaves as normal. Wrt. `the-` identifiers. Try this: ```scheme (define (foo a-number x) (let ([the-number 42]) (+ x the-number))) (foo 1 2) ``` I expect to see 44 as result. ---
**Author:** ![rvdalen](https://avatars.discourse-cdn.com/v4/letter/r/b4bc9f/32.png) [@rvdalen](https://racket.discourse.group/u/rvdalen)\ **Post date:** [May 31, 2024, 5:54pm UTC](https://racket.discourse.group/t/naming-convention-for-structs/2939/14 "2024-05-31T17:54:18Z")
Nooooooo 🙂 Dammit, thanks for letting me know. I will now choose a different suffix and update a lot of code 😅 ---
**Author:** ![rvdalen](https://avatars.discourse-cdn.com/v4/letter/r/b4bc9f/32.png) [@rvdalen](https://racket.discourse.group/u/rvdalen)\ **Post date:** [May 31, 2024, 10:18pm UTC](https://racket.discourse.group/t/naming-convention-for-structs/2939/15 "2024-05-31T22:18:53Z")
I have changed my suffix to '.' so my struct ids now look like this: ```scheme (struct person. ...) ```