How to use instanced struct values in a match statement?
I have an example instanced struct, named args, of the original struct Args.
struct Args {
arg1: bool,
arg2: bool,
}
and the instanced struct being:
let args = Args {
arg1: true,
arg2: false,
}
Using these arguments, I am attempting to avoid a jumble of if-else statments and just use a match statement. However, when attempting to perform the following:
match true {
args.arg1 => println!("Argument 1 is true!"),
args.arg2 => println!("Argument 2 is true!"),
}
I am given the error
error: expected one of `=>`, `@`, `if`, or `|`, found `.`
--> src/main.rs:13:13
|
13 | args.arg1 => println!("Argument one is true"),
| ^ expected one of `=>`, `@`, `if`, or `|` here
error: aborting due to previous error
Is there an escape character sequence I should use to avoid this, or is this simply incorrect syntax?
syntax rust
asked Nov 23 '18 at 0:05
aethioaethio
812
add a comment |
I have an example instanced struct, named args, of the original struct Args.
struct Args {
arg1: bool,
arg2: bool,
}
and the instanced struct being:
let args = Args {
arg1: true,
arg2: false,
}
Using these arguments, I am attempting to avoid a jumble of if-else statments and just use a match statement. However, when attempting to perform the following:
match true {
args.arg1 => println!("Argument 1 is true!"),
args.arg2 => println!("Argument 2 is true!"),
}
I am given the error
error: expected one of `=>`, `@`, `if`, or `|`, found `.`
--> src/main.rs:13:13
|
13 | args.arg1 => println!("Argument one is true"),
| ^ expected one of `=>`, `@`, `if`, or `|` here
error: aborting due to previous error
Is there an escape character sequence I should use to avoid this, or is this simply incorrect syntax?
syntax rust
asked Nov 23 '18 at 0:05
aethioaethio
812
Does this help ?
– Stargateur
Nov 23 '18 at 0:15
It's good to know this is possible, but my production program is using several arguments, not two alone... Iterating over all possible combinations would be a pain :/
– aethio
Nov 23 '18 at 0:20
1
I can't help you about something I can't see.
– Stargateur
Nov 23 '18 at 0:24
For example, instead of just arg1 and arg2, it has arg1 through arg10.
– aethio
Nov 23 '18 at 0:26
add a comment |
I have an example instanced struct, named args, of the original struct Args.
struct Args {
arg1: bool,
arg2: bool,
}
and the instanced struct being:
let args = Args {
arg1: true,
arg2: false,
}
Using these arguments, I am attempting to avoid a jumble of if-else statments and just use a match statement. However, when attempting to perform the following:
match true {
args.arg1 => println!("Argument 1 is true!"),
args.arg2 => println!("Argument 2 is true!"),
}
I am given the error
error: expected one of `=>`, `@`, `if`, or `|`, found `.`
--> src/main.rs:13:13
|
13 | args.arg1 => println!("Argument one is true"),
| ^ expected one of `=>`, `@`, `if`, or `|` here
error: aborting due to previous error
Is there an escape character sequence I should use to avoid this, or is this simply incorrect syntax?
syntax rust
asked Nov 23 '18 at 0:05
aethioaethio
812
I have an example instanced struct, named args, of the original struct Args.
struct Args {
arg1: bool,
arg2: bool,
}
and the instanced struct being:
let args = Args {
arg1: true,
arg2: false,
}
Using these arguments, I am attempting to avoid a jumble of if-else statments and just use a match statement. However, when attempting to perform the following:
match true {
args.arg1 => println!("Argument 1 is true!"),
args.arg2 => println!("Argument 2 is true!"),
}
I am given the error
error: expected one of `=>`, `@`, `if`, or `|`, found `.`
--> src/main.rs:13:13
|
13 | args.arg1 => println!("Argument one is true"),
| ^ expected one of `=>`, `@`, `if`, or `|` here
error: aborting due to previous error
Is there an escape character sequence I should use to avoid this, or is this simply incorrect syntax?
syntax rust
syntax rust
asked Nov 23 '18 at 0:05
aethioaethio
812
asked Nov 23 '18 at 0:05
aethioaethio
812
asked Nov 23 '18 at 0:05
aethioaethio
812
asked Nov 23 '18 at 0:05
aethioaethio
812
asked Nov 23 '18 at 0:05
aethioaethio
812
812
Does this help ?
– Stargateur
Nov 23 '18 at 0:15
It's good to know this is possible, but my production program is using several arguments, not two alone... Iterating over all possible combinations would be a pain :/
– aethio
Nov 23 '18 at 0:20
1
I can't help you about something I can't see.
– Stargateur
Nov 23 '18 at 0:24
For example, instead of just arg1 and arg2, it has arg1 through arg10.
– aethio
Nov 23 '18 at 0:26
add a comment |
Does this help ?
– Stargateur
Nov 23 '18 at 0:15
It's good to know this is possible, but my production program is using several arguments, not two alone... Iterating over all possible combinations would be a pain :/
– aethio
Nov 23 '18 at 0:20
1
I can't help you about something I can't see.
– Stargateur
Nov 23 '18 at 0:24
For example, instead of just arg1 and arg2, it has arg1 through arg10.
– aethio
Nov 23 '18 at 0:26
Does this help ?
– Stargateur
Nov 23 '18 at 0:15
Does this help ?
– Stargateur
Nov 23 '18 at 0:15
It's good to know this is possible, but my production program is using several arguments, not two alone... Iterating over all possible combinations would be a pain :/
– aethio
Nov 23 '18 at 0:20
It's good to know this is possible, but my production program is using several arguments, not two alone... Iterating over all possible combinations would be a pain :/
– aethio
Nov 23 '18 at 0:20
1
1
I can't help you about something I can't see.
– Stargateur
Nov 23 '18 at 0:24
I can't help you about something I can't see.
– Stargateur
Nov 23 '18 at 0:24
For example, instead of just arg1 and arg2, it has arg1 through arg10.
– aethio
Nov 23 '18 at 0:26
For example, instead of just arg1 and arg2, it has arg1 through arg10.
– aethio
Nov 23 '18 at 0:26
add a comment |
1 Answer
1
active
oldest
votes
It is unclear to me what you mean to happen for the case where you have both arg1 and arg2 set to true - do you just want the first branch of the if to be taken, or both?
If its both - then really you should just use multiple ifs.
if args.arg1 { println!("Argument 1 is true!") }
if args.arg2 { println!("Argument 2 is true!") }
If only one should occur preferring arg1, then you can use a struct destructure
match args {
Args { arg1:true, ..} => println!("Argument 1 is true!"),
Args { arg2:true, ..} => println!("Argument 2 is true!"),
_ => println!("Neither is true")
}
You can use the match to match more complex cases too
match args {
Args {arg1:true, arg2:false, ...} => println!("TF"),
}
However, if at most one argument can be true at once, you really have an enum and should probably handle it like
enum Arg {
None,
Arg1,
Arg2
}
fn main() {
let args:Args = get_argument();
match args {
Args::None => println!("none"),
Args::Arg1 => println!("Argument 1 is true!"),
Args::Arg2 => println!("Argument 2 is true!")
}
}
edited Nov 23 '18 at 1:36
aethio
812
answered Nov 23 '18 at 0:29
Michael AndersonMichael Anderson
46.2k697150
It's a good point you raise! I created this with the expectation that only one arg would be true at once.
– aethio
Nov 23 '18 at 0:43
If only one is true at once, you really have an enum. I'll update the code to detail that too.
– Michael Anderson
Nov 23 '18 at 0:46
I haven't yet gotten to the Enums chapter of The Book yet; but your code is perfect in my situation.. thank you!!
– aethio
Nov 23 '18 at 0:56
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53439273%2fhow-to-use-instanced-struct-values-in-a-match-statement%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
It is unclear to me what you mean to happen for the case where you have both arg1 and arg2 set to true - do you just want the first branch of the if to be taken, or both?
If its both - then really you should just use multiple ifs.
if args.arg1 { println!("Argument 1 is true!") }
if args.arg2 { println!("Argument 2 is true!") }
If only one should occur preferring arg1, then you can use a struct destructure
match args {
Args { arg1:true, ..} => println!("Argument 1 is true!"),
Args { arg2:true, ..} => println!("Argument 2 is true!"),
_ => println!("Neither is true")
}
You can use the match to match more complex cases too
match args {
Args {arg1:true, arg2:false, ...} => println!("TF"),
}
However, if at most one argument can be true at once, you really have an enum and should probably handle it like
enum Arg {
None,
Arg1,
Arg2
}
fn main() {
let args:Args = get_argument();
match args {
Args::None => println!("none"),
Args::Arg1 => println!("Argument 1 is true!"),
Args::Arg2 => println!("Argument 2 is true!")
}
}
edited Nov 23 '18 at 1:36
aethio
812
answered Nov 23 '18 at 0:29
Michael AndersonMichael Anderson
46.2k697150
It's a good point you raise! I created this with the expectation that only one arg would be true at once.
– aethio
Nov 23 '18 at 0:43
If only one is true at once, you really have an enum. I'll update the code to detail that too.
– Michael Anderson
Nov 23 '18 at 0:46
I haven't yet gotten to the Enums chapter of The Book yet; but your code is perfect in my situation.. thank you!!
– aethio
Nov 23 '18 at 0:56
add a comment |
It is unclear to me what you mean to happen for the case where you have both arg1 and arg2 set to true - do you just want the first branch of the if to be taken, or both?
If its both - then really you should just use multiple ifs.
if args.arg1 { println!("Argument 1 is true!") }
if args.arg2 { println!("Argument 2 is true!") }
If only one should occur preferring arg1, then you can use a struct destructure
match args {
Args { arg1:true, ..} => println!("Argument 1 is true!"),
Args { arg2:true, ..} => println!("Argument 2 is true!"),
_ => println!("Neither is true")
}
You can use the match to match more complex cases too
match args {
Args {arg1:true, arg2:false, ...} => println!("TF"),
}
However, if at most one argument can be true at once, you really have an enum and should probably handle it like
enum Arg {
None,
Arg1,
Arg2
}
fn main() {
let args:Args = get_argument();
match args {
Args::None => println!("none"),
Args::Arg1 => println!("Argument 1 is true!"),
Args::Arg2 => println!("Argument 2 is true!")
}
}
edited Nov 23 '18 at 1:36
aethio
812
answered Nov 23 '18 at 0:29
Michael AndersonMichael Anderson
46.2k697150
It's a good point you raise! I created this with the expectation that only one arg would be true at once.
– aethio
Nov 23 '18 at 0:43
If only one is true at once, you really have an enum. I'll update the code to detail that too.
– Michael Anderson
Nov 23 '18 at 0:46
I haven't yet gotten to the Enums chapter of The Book yet; but your code is perfect in my situation.. thank you!!
– aethio
Nov 23 '18 at 0:56
add a comment |
It is unclear to me what you mean to happen for the case where you have both arg1 and arg2 set to true - do you just want the first branch of the if to be taken, or both?
If its both - then really you should just use multiple ifs.
if args.arg1 { println!("Argument 1 is true!") }
if args.arg2 { println!("Argument 2 is true!") }
If only one should occur preferring arg1, then you can use a struct destructure
match args {
Args { arg1:true, ..} => println!("Argument 1 is true!"),
Args { arg2:true, ..} => println!("Argument 2 is true!"),
_ => println!("Neither is true")
}
You can use the match to match more complex cases too
match args {
Args {arg1:true, arg2:false, ...} => println!("TF"),
}
However, if at most one argument can be true at once, you really have an enum and should probably handle it like
enum Arg {
None,
Arg1,
Arg2
}
fn main() {
let args:Args = get_argument();
match args {
Args::None => println!("none"),
Args::Arg1 => println!("Argument 1 is true!"),
Args::Arg2 => println!("Argument 2 is true!")
}
}
edited Nov 23 '18 at 1:36
aethio
812
answered Nov 23 '18 at 0:29
Michael AndersonMichael Anderson
46.2k697150
It is unclear to me what you mean to happen for the case where you have both arg1 and arg2 set to true - do you just want the first branch of the if to be taken, or both?
If its both - then really you should just use multiple ifs.
if args.arg1 { println!("Argument 1 is true!") }
if args.arg2 { println!("Argument 2 is true!") }
If only one should occur preferring arg1, then you can use a struct destructure
match args {
Args { arg1:true, ..} => println!("Argument 1 is true!"),
Args { arg2:true, ..} => println!("Argument 2 is true!"),
_ => println!("Neither is true")
}
You can use the match to match more complex cases too
match args {
Args {arg1:true, arg2:false, ...} => println!("TF"),
}
However, if at most one argument can be true at once, you really have an enum and should probably handle it like
enum Arg {
None,
Arg1,
Arg2
}
fn main() {
let args:Args = get_argument();
match args {
Args::None => println!("none"),
Args::Arg1 => println!("Argument 1 is true!"),
Args::Arg2 => println!("Argument 2 is true!")
}
}
edited Nov 23 '18 at 1:36
aethio
812
answered Nov 23 '18 at 0:29
Michael AndersonMichael Anderson
46.2k697150
edited Nov 23 '18 at 1:36
aethio
812
edited Nov 23 '18 at 1:36
aethio
812
edited Nov 23 '18 at 1:36
aethio
812
812
answered Nov 23 '18 at 0:29
Michael AndersonMichael Anderson
46.2k697150
answered Nov 23 '18 at 0:29
Michael AndersonMichael Anderson
46.2k697150
answered Nov 23 '18 at 0:29
Michael AndersonMichael Anderson
46.2k697150
46.2k697150
It's a good point you raise! I created this with the expectation that only one arg would be true at once.
– aethio
Nov 23 '18 at 0:43
If only one is true at once, you really have an enum. I'll update the code to detail that too.
– Michael Anderson
Nov 23 '18 at 0:46
I haven't yet gotten to the Enums chapter of The Book yet; but your code is perfect in my situation.. thank you!!
– aethio
Nov 23 '18 at 0:56
add a comment |
It's a good point you raise! I created this with the expectation that only one arg would be true at once.
– aethio
Nov 23 '18 at 0:43
If only one is true at once, you really have an enum. I'll update the code to detail that too.
– Michael Anderson
Nov 23 '18 at 0:46
I haven't yet gotten to the Enums chapter of The Book yet; but your code is perfect in my situation.. thank you!!
– aethio
Nov 23 '18 at 0:56
It's a good point you raise! I created this with the expectation that only one arg would be true at once.
– aethio
Nov 23 '18 at 0:43
It's a good point you raise! I created this with the expectation that only one arg would be true at once.
– aethio
Nov 23 '18 at 0:43
If only one is true at once, you really have an enum. I'll update the code to detail that too.
– Michael Anderson
Nov 23 '18 at 0:46
If only one is true at once, you really have an enum. I'll update the code to detail that too.
– Michael Anderson
Nov 23 '18 at 0:46
I haven't yet gotten to the Enums chapter of The Book yet; but your code is perfect in my situation.. thank you!!
– aethio
Nov 23 '18 at 0:56
I haven't yet gotten to the Enums chapter of The Book yet; but your code is perfect in my situation.. thank you!!
– aethio
Nov 23 '18 at 0:56
add a comment |
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53439273%2fhow-to-use-instanced-struct-values-in-a-match-statement%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Does this help ?
– Stargateur
Nov 23 '18 at 0:15
It's good to know this is possible, but my production program is using several arguments, not two alone... Iterating over all possible combinations would be a pain :/
– aethio
Nov 23 '18 at 0:20
1
I can't help you about something I can't see.
– Stargateur
Nov 23 '18 at 0:24
For example, instead of just arg1 and arg2, it has arg1 through arg10.
– aethio
Nov 23 '18 at 0:26