digitalmars.D.learn - shouldn't this code at least trigger a warning?
- ketmar (17/17) Apr 28 2015 subj. the code:
- "Marc =?UTF-8?B?U2Now7x0eiI=?= <schuetzm gmx.net> (4/22) Apr 29 2015 Agreed, this should be an error. Variables declared in one case
- Steven Schveighoffer (9/33) Apr 29 2015 I thought they were? A switch scope is just like a normal scope, but
- Gary Willoughby (2/20) Apr 29 2015 Please raise an issue in bugzilla. This is obviously an error.
- ketmar (2/3) Apr 30 2015 done: https://issues.dlang.org/show_bug.cgi?id=3D14532=
- H. S. Teoh via Digitalmars-d-learn (16/37) Apr 29 2015 Switch statements in D allow all sorts of abominations, if only you
- =?UTF-8?B?QWxpIMOHZWhyZWxp?= (3/6) Apr 29 2015 http://en.wikipedia.org/wiki/Duff%27s_device
- ketmar (9/21) Apr 30 2015 yes, `switch` is one of those legacy cans of worms. i'm afraid that it's...
subj. the code: void main () { import std.stdio; char ch =3D '!'; switch (ch) { int n =3D 42; case '!': writeln(n, ": wow!"); break; default: } } i think that such abomination should: 1. be forbidden, or 2. trigger a warning, or 3. execute initializer anyway. currently the code is allowed, no warnings triggered, yet `n` is=20 uninitialized. and having uninitialized variable without "=3Dvoid" "should=20 not be".=
Apr 28 2015
On Wednesday, 29 April 2015 at 06:37:44 UTC, ketmar wrote:subj. the code: void main () { import std.stdio; char ch = '!'; switch (ch) { int n = 42; case '!': writeln(n, ": wow!"); break; default: } } i think that such abomination should: 1. be forbidden, or 2. trigger a warning, or 3. execute initializer anyway. currently the code is allowed, no warnings triggered, yet `n` is uninitialized. and having uninitialized variable without "=void" "should not be".Agreed, this should be an error. Variables declared in one case block aren't even visible in other case blocks, this was probably an oversight.
Apr 29 2015
On 4/29/15 5:25 AM, "Marc =?UTF-8?B?U2Now7x0eiI=?= <schuetzm gmx.net>" wrote:On Wednesday, 29 April 2015 at 06:37:44 UTC, ketmar wrote:I thought they were? A switch scope is just like a normal scope, but with a bunch of labels. They should be visible in all *trailing* case blocks, since the rule is that your code that uses it must come after the declaration. I agree the above should not be allowed. It's clear the compiler can detect a situation where n is used but not initialized. -Stevesubj. the code: void main () { import std.stdio; char ch = '!'; switch (ch) { int n = 42; case '!': writeln(n, ": wow!"); break; default: } } i think that such abomination should: 1. be forbidden, or 2. trigger a warning, or 3. execute initializer anyway. currently the code is allowed, no warnings triggered, yet `n` is uninitialized. and having uninitialized variable without "=void" "should not be".Agreed, this should be an error. Variables declared in one case block aren't even visible in other case blocks, this was probably an oversight.
Apr 29 2015
On Wednesday, 29 April 2015 at 06:37:44 UTC, ketmar wrote:subj. the code: void main () { import std.stdio; char ch = '!'; switch (ch) { int n = 42; case '!': writeln(n, ": wow!"); break; default: } } i think that such abomination should: 1. be forbidden, or 2. trigger a warning, or 3. execute initializer anyway. currently the code is allowed, no warnings triggered, yet `n` is uninitialized. and having uninitialized variable without "=void" "should not be".Please raise an issue in bugzilla. This is obviously an error.
Apr 29 2015
On Wed, 29 Apr 2015 10:48:36 +0000, Gary Willoughby wrote:Please raise an issue in bugzilla. This is obviously an error.done: https://issues.dlang.org/show_bug.cgi?id=3D14532=
Apr 30 2015
On Wed, Apr 29, 2015 at 06:37:44AM +0000, ketmar via Digitalmars-d-learn wrote:subj. the code: void main () { import std.stdio; char ch = '!'; switch (ch) { int n = 42; case '!': writeln(n, ": wow!"); break; default: } } i think that such abomination should: 1. be forbidden, or 2. trigger a warning, or 3. execute initializer anyway. currently the code is allowed, no warnings triggered, yet `n` is uninitialized. and having uninitialized variable without "=void" "should not be".Switch statements in D allow all sorts of abominations, if only you would try it. I think it was originally designed to support a particular loop idiom (sorry I forgot what it was called, and don't have time to look it up right now), but in the process this also opened the door to all sorts of nasty infelicities that probably breaks the type system, control flow, and many other things. Basically, the block inside a switch statement essentially amounts to free-for-all spaghetti code where you're free to jump around case labels willy-nilly, declare variables and jump over their initializations, break out of loops with goto case, or enter into the middle of a loop, and all sorts of other crazy things that, ostensibly, you shouldn't be able to do in a language like D. T -- Let's eat some disquits while we format the biskettes.
Apr 29 2015
On 04/29/2015 07:57 AM, H. S. Teoh via Digitalmars-d-learn wrote:Switch statements in D allow all sorts of abominations, if only you would try it. I think it was originally designed to support a particular loop idiom (sorry I forgot what it was calledhttp://en.wikipedia.org/wiki/Duff%27s_device Ali
Apr 29 2015
On Wed, 29 Apr 2015 07:57:07 -0700, H. S. Teoh via Digitalmars-d-learn wrote:Switch statements in D allow all sorts of abominations, if only you would try it. I think it was originally designed to support a particular loop idiom (sorry I forgot what it was called, and don't have time to look it up right now), but in the process this also opened the door to all sorts of nasty infelicities that probably breaks the type system, control flow, and many other things. Basically, the block inside a switch statement essentially amounts to free-for-all spaghetti code where you're free to jump around case labels willy-nilly, declare variables and jump over their initializations, break out of loops with goto case, or enter into the middle of a loop, and all sorts of other crazy things that, ostensibly, you shouldn't be able to do in a language like D.yes, `switch` is one of those legacy cans of worms. i'm afraid that it's=20 too late to redesign it, but it would be nice if each `case` will be an=20 implicit `{}` block, and `goto case`/`break` will be allowed only as a=20 last statement in `case` block. and unlabeled code in `switch` should be=20 forbidden to. but, as i said, it's too late to introduce such breaking change to=20 language.=
Apr 30 2015